Talk:List of largest stars/Archive 4

Archive 1

Archive 2

Archive 3

Archive 4

Archive 5

TESS Input Catalog

I checked the methods used in the TIC catalog, and the formula for radius is only appropriate for dwarf-like stars, i. e. not giants or supergiants. Additionally there is a great degree of uncertainty in the Gaia parallaxes of RSGs. All entries in this list or standalone wikipedia starboxes should have the radius (and other stellar parameters) from TIC removed immediately. Find a different source whenever possible, otherwise leave it blank. nussun (talk) 14:37, 9 February 2022 (UTC)

Okay, I do it then.--The Space Enthusiast (talk) 23:21, 9 February 2022 (UTC)

Recent Changes

Recently, UY Scuti has been removed from the list by User:Ysku. It is a move that I support, as its distance estimates are unreliable. He also moved NML Cygni back up from 1,183 RSOL to 1,639 RSOL. If I remember correctly we discussed about the choice between the 2 conflicting radii, and whether we should use the 1,183 RSOL estimate from 2010, or the 1,639 RSOL estimate from 2012. I would like to know your opinions about which of the 2 radii you would use. Personally, I am quite undecided since both estimates seem to be reliable.--The Space Enthusiast (talk) 02:31, 19 February 2022 (UTC)

But The thing is The fact that 2010 estimate uses Very high temperature - 3834 K - which would make NML Cyg M0 star, which is unlikely. In that paper NML Cygni is also too close Ysku (talk) 09:24, 19 February 2022 (UTC)

Consistent reference format

I think we should adopt a standard for how references are formatted, this would greatly improve consistency. nussun (talk) 09:10, 22 February 2022 (UTC)

If you're referring to how 90% of the references are at the end of the article but people keep insisting on putting them in the table, yes, but that's something we already do and just need to enforce it. Primefac (talk) 09:13, 22 February 2022 (UTC)

Not all of them use the same fields, have the same date format, etc. Some of them use the url parameter and some don't. I just don't like the inconsistency of it all. nussun (talk) 09:16, 22 February 2022 (UTC)

Date format is easy to update. I don't think we should remove URLs from articles that have them, because that removes availability. Primefac (talk) 09:20, 22 February 2022 (UTC)

{{cite journal}} should not normally include a url. There are multiple fields available for standardised linking to all the common journal identifiers and quite a few uncommon ones. Use those to prevent WP:linkrot. There are also fields available to indicate several of the identifiers which may link to free editions of the journal paper and which will cause the whole title to be linked. Only very rarely would a url be useful when none of the standard identifiers links to a free-to-read copy and another url does, and even in those cases use caution since they may be "pirate" versions circumventing copyright. Lithopsian (talk) 14:55, 22 February 2022 (UTC)

What do we do about the list?

It's getting more and more clear to me how meaningless the concept of 'the largest known stars' actually are. No matter how hard we try the list is always gonna end up messy, all radii here are uncertain, and this is by no means anywhere close to complete list. Additionally no one can agree which radius estimate to use for certain stars. It really makes me feel like the list should just be deleted at this point. nussun (talk) 13:35, 22 February 2022 (UTC)

That's an easy opinion to empathise with. However, the question should always be "how notable is the title", not "how rubbish are the contents". If the title is a notable subject, then it stays and we have to keep arguing about the contents. As you point out, the contents are always going to be at best a mess, and at worst completely at odds with WP policies. It could be argued that the article should only contain stars which have been described in reliable sources as among the largest known. We shouldn't be making such sweeping decisions for ourselves based on a comparison of multiple different primary sources, that is WP:SYNTHESIS. Still, that would make for a fairly short list, and arguably worse than what we have now. Lithopsian (talk) 14:59, 22 February 2022 (UTC)

Stephenson 2-18

Stephenson 2-18 is estimated to be larger than UY Scuti, potentially engulfing Saturn's orbit. 191.246.32.0 (talk) 01:20, 8 January 2022 (UTC)

That star can't be added on the list because it's too unreliable. SpaceImplorerExplorerImplorer (talk) 16:41 29 January 2022 (UTC)

That could be said for pretty much every star on the list too. nussun (talk) 18:44, 31 January 2022 (UTC)

I am curious: I wonder why UY Scuti doesn't have the same uncertainty note regarding its radius...--The Space Enthusiast (talk) 02:22, 1 February 2022 (UTC)

True, UY Scuti's distance is nowhere near well-constrained and is still very uncertain. You could even argue it's more uncertain than Stephenson 2-18 because St2-18 at least has a possible cluster membership. nussun (talk) 06:54, 1 February 2022 (UTC)

Yeah, Exactly! — Preceding unsigned comment added by The Space Enthusiast (talk • contribs) 09:38, 1 February 2022 (UTC)

I think the reason why UY Scuti does not have an uncertainty note regarding its radius is because of the fact that we don’t have a research paper saying that it is uncertain or dubious, only a paper saying that it is more extreme than what we would expect. If we added one without a reliable reference then it would be original research.Stephenson 2-18,meanwhile has a mentioned uncertainty in the paper that gave its large radius of over 2,150 solar radii; it says that the distances to the stars mentioned in the paper were uncertain with a relative error of 50 percent. However, I wonder what relative error means, is it different from only the word error?—The Space Enthusiast (talk) 00:03, 16 March 2022 (UTC)

Calculated Radii

Recently, there was quite a lot of changes. Some changes involved adding Stefan-Boltzmann law calculated radii, such as NML Cygni's 1,639 solar radii estimate and Stephenson 2-18's 2,150 solar radii estimate. Now, the question is, what do we do about the calculated radii? I am sorry for not editing much, I am quite undecided with it again as while the luminosity and temperature given in the reference do correspond with these radii, there are other problems. The list might become very messy and uncertain, pushing some to discuss about deleting it. (discussed above) What them=n, should we do?--The Space Enthusiast (talk) 03:19, 28 February 2022 (UTC)

Calculated radii to me might be considered original research, because it is a calculation of a value not present in the paper. It is also our own assumption that the Stefan-Boltzmann law even applies to extreme stars like these. nussun (talk) 11:15, 28 February 2022 (UTC)

WP:CALC, and the existence of {{Solar radius calculator}}, would indicate that it is not original research to take a temperature and luminosity and use those in the Stefan–Boltzmann law to find the radius. Hell, we created the template because we wanted people to input the values found in the literature rather than doing their own calculations so that the template could correctly calculate them (rather than assuming the user has done it properly). Primefac (talk) 13:05, 28 February 2022 (UTC)

It's still an assumption that the law even applies here to such extreme stars. nussun (talk) 18:18, 28 February 2022 (UTC)

The Stefan–Boltzmann law is a physical relation that applies to anything that can be regarded as a black body, and even red supergiants are pretty good black bodies. It is the very definition of the radius of a star used by astronomers, or the definition of effective temperature if you want to phrase it that way round. The calculation is simple and straightforward, it requires no subjective decisions, operates on well-defined fixed values and hence satisfies WP:CALC. Other definitions of radius are applied in certain extreme conditions (eg. for WR stars) but we should avoid using them for direct comparisons. In particular direct measurements of angular radii may not be comparable to radii corresponding to effective temperatures - see individual published papers for discussion on whether they are likely to be comparable or not. Lithopsian (talk) 19:17, 28 February 2022 (UTC)

I recently looked at the list to edit If UY Scuti's location on the list was colored grey to indicate possible inaccuracies, but I also found out that Many stars on the list have sizes that were calculated via Stefan-Boltzmann law! What do we do about them? I personally will keep them for now because a stars temperature and luminosity corresponds to its radius--The Space Enthusiast (talk) 23:43, 15 March 2022 (UTC)

We do nothing. Stefan–Boltzmann law is a law for a reason: it's how the universe works. I still maintain that if a source only gives L and T_eff, we should use the template to make it more clear when editing the source where the (calculated) radius came from in the reference. Primefac (talk) 10:15, 16 March 2022 (UTC)

What about the other calculated radii, like that of NML Cygni? —The Space Enthusiast (talk) 11:45, 16 March 2022 (UTC)

I'm not sure I understand the question; NML Cygni's radius is calculated via Stefan-Botlzmann, but [1] gives the R_☉ value so we use that directly. Primefac (talk) 11:48, 16 March 2022 (UTC)

I'm not saying we shouldn't use de Beck etal. (2010), but the radii in there are really all over the place, calculated from some fairly flimsy assumptions. Newer sources, albeit requiring calculations, may be more reliable, although there really isn't a good solid consensus for the size of this unusual star that I'm aware of. I've just done another trawl of the literature and still nothing good. There's this, but it is just lifting data from here. This 2021 paper gives a radius (in cm), but again it is just quoting the same old(-ish) sources. Looking at the glass as half-full, it could be considered an expression of current scientific consensus. Zhang et al (2012) is probably the best data for the star, but given that it sits on the fence wrt the effective temperature, we can't get a single radius value from that paper. Lithopsian (talk) 14:57, 16 March 2022 (UTC)

I personally don't think we should use De Beck et al. 2010 for a couple of reasons:

• It uses an outdated distance.
• NML Cygni is known to be a cooler star than what the paper would suggest.
• The methods used might be dubious because of the great overestimation of radius for IRC +10420 and Betelgeuse.

Even if you could still consider it reliable the newer 2012 source is far superior in every way. nussun (talk) 07:39, 17 March 2022 (UTC)

"the newer 2012 source is far superior in every way" - yes, except that it doesn't give a radius, or even pick a temperature ;) Lithopsian (talk) 16:44, 17 March 2022 (UTC)

I think I remember it saying the 2,500 K provided the best fit to some data, but it would obviously suggest an unreasonably low temperature and high radius. I'm very unsure with this star to to be honest. nussun (talk) 20:05, 17 March 2022 (UTC)

Yes, it says that 2,500 K is the best fit temperature to the infrared spectrum. --The Space Enthusiast (talk) 23:23, 17 March 2022 (UTC)

IRAS 05346-6949

This star used to be part of the list, with a claimed size of 2,064 solar radii. While it is classified as an AGB star by some references, More recent papers classify it as an extreme red supergiant, like WOH G64 and IRAS 05280-6910. When I looked at the reference for its alleged size, it doesn't show up, so I want to know where that claimed size came from and why the star was removed from the list.The Space Enthusiast (talk) 09:50, 23 April 2022 (UTC)

You answered your own question, mate... When I looked at the reference for its alleged size, it doesn't show up. Primefac (talk) 12:30, 23 April 2022 (UTC)

Ok, but I was just curious about where it came from. — Preceding unsigned comment added by The Space Enthusiast (talk • contribs) 12:39, 23 April 2022 (UTC)

You'd have to look through the history and ask the user who originally added it. Primefac (talk) 12:42, 23 April 2022 (UTC)

It was listed ([2]) with a temperature of 2,673 K and a log luminosity of 5.292. The given reference lists properties for the star in a supplemental data file. It gives a photometric bolometric magnitude of -8.49, which correspond to logL 5.295 (or 5.296?), and a temperature of 2,673 K. It also gives a SED-fitting bolometric magnitude of -9.5. Lithopsian (talk) 13:09, 24 April 2022 (UTC)

References

LGGS Stars

The radii used for the LGGS stars in the M33 table are taken from Massey et al. 2009, however only seem to use radii from one column ((V − K)₀ specifically) whilst there are two other given radii in two other columns (V and K band). Should these other radii be included aswell in the table or are the radii used currently enough? Faren29 (talk) 13:30, 2 May 2022 (UTC)

Yes, please add them, but we might need to ask the others as well. I am currently busy.--The Space Enthusiast (talk) 13:51, 2 May 2022 (UTC)

LI-LMC 60

The paper gets temperature and luminosity from older sources. The luminosity definetly seems accurate, but the given cool temperature of 2,500 K seems a bit doubtful. What are everyone's thoughts on this? nussun (talk) 05:25, 13 May 2022 (UTC)

The paper has a little commentary on the temperature. It looks like they just had a choice between 2,500 K and a much warmer temperature. 2,500 K was a better match, so that's the value it got, but in reality a slightly warmer temperature might have been an even better match if they'd had one available. Some other papers for other stars in the table suffer from similar issues with grids of values, but perhaps not so obvious as this one. Some of the temperatures used in the table are also likely to be just plain wrong, for example fitting a single black body temperature to a central source surrounded by warm dust will give an unreasonably cool temperature. Lithopsian (talk) 09:33, 13 May 2022 (UTC)

Stephensen 2-18

Stephensen 2 18 is the largrst known star i believe. It is in the milky way, only about 20,000 ly away from us humans, its solar radii is well over 2000 units, and it is not on this list. I think this should be ammended 213.249.219.89 (talk) 13:27, 7 May 2022 (UTC)

If you have a reliable source, please add it here so that we can discuss the matter further. Primefac (talk) 13:46, 7 May 2022 (UTC)

Of course, we have --The Space Enthusiast (talk) 05:17, 8 May 2022 (UTC)

Courtesy ping to Sarjono21, who is editing-warring with The Space Enthusiast about this entry. Please don't edit-war to re-add it, instead let's come to a consensus about what to do about it. Primefac (talk) 11:15, 8 May 2022 (UTC)

My apologies, the war was with SpaceImplorerExplorerImplorer, not Enthusiast. Easy to get those two confused. Pinging since they don't appear to be involved in the talk page since January. Primefac (talk) 13:07, 8 May 2022 (UTC)

I am sorry for the confusion regarding our names, but do note that we can be differentiated via our opiniions on St2-18 and VY CMa.--The Space Enthusiast (talk) 14:07, 8 May 2022 (UTC)

Add it back. We have a source and we (most of us) have agreed that the calculation is not only valid but encouraged with a template to support it. I can't see any reason to ignore this source compared to many others just because it is up-front about the uncertainties involved. For example, we know that the distance to UY Scuti used (assumed) by the given reference is at best uncertain by a huge margin (very old and basically a guess) and at worst is just wrong (we have a Gaia parallax, albeit not a particularly reliable one). The only reason Stephenson 2-18 is not in the list now is that the most persistent edit-warrior was the one that wanted it gone. Lithopsian (talk) 13:03, 8 May 2022 (UTC)

I'll admit, I haven't been involved in the conversation about Stephensen, but I do agree with if SIEI is the only one opposed, the consensus does appear (at least right now, in this discussion) to be to keep it added along with the below-mentioned caveats. Primefac (talk) 13:08, 8 May 2022 (UTC)

I am now going to add it. If SpaceImplorerExplorerImplorer reverts it, I will call him to this discussion.--The Space Enthusiast (talk) 14:37, 8 May 2022 (UTC)

I would be in favour of keeping Stephenson 2-18 off the list. We should be very sceptical of such extreme radii (>1,500 solar radii) and only include such stars when there is little doubt over the accuracy of the calculated radius. SpaceImplorerExplorerImplorer (talk) 15:07 8 May 2022 (UTC)

Guys, He just undid the re-addition of Stephenson 2-18, but this time the reason why is because of the fact that the star size was “overestimated”.—The Space Enthusiast (talk) 16:36, 8 May 2022 (UTC)

It isn’t just because it is “overestimated”, it is also because of the fact that it is very unreliable and therefore you can’t add it to the list. You could also argue that you could remove stars like UY Scuti off the list as well. Also if you want to include calculated radii like Stephenson 2-18 that also include a large amount of uncertainty, you just get a messy list again with hundreds of stars. SpaceImplorerExplorerImplorer (talk) 16:52, 8 May 2022 (UTC)

How is it unreliable?--The Space Enthusiast (talk) 17:12, 8 May 2022 (UTC)

The article itself expresses a very high degree of uncertainty in the distance and the calculated radius is much higher than you would expect for even a very large red supergiant. SpaceImplorerExplorerImplorer (talk) 17:15, 8 May 2022 (UTC)

Please read the messages further above.—The Space Enthusiast (talk) 06:11, 9 May 2022 (UTC)

Which one? SpaceImplorerExplorerImplorer (talk) 13:24, 9 May 2022 (UTC)

The one by Lithopsian.—The Space Enthusiast (talk) 13:34, 9 May 2022 (UTC)

St2-18 caveats

If we're gonna include Stephenson 2-18 in the list we have to make the countless amounts of caveats for this specific star clear. nussun (talk) 05:31, 8 May 2022 (UTC)

Definitely. I already added one, or maybe we can't include it at all. While it is my favorite star, there's just so many caveats to consider so I don't want to add it.--The Space Enthusiast (talk) 05:44, 8 May 2022 (UTC)

Edit war

Please stop editing the page until a consensus has been reached. nussun (talk) 19:25, 8 May 2022 (UTC)

Yes, I have stopped. only SIEI seems to be opposed, but I think we need more discussion. Please engage in this discussion, so we can settle this altogether, and we don’t have to wage war.—The Space Enthusiast (talk) 01:34, 9 May 2022 (UTC)

References

More discussion isn't really necessary. A consensus has already been reached and only SpaceImplorerExplorerImplorer appears to disagree with adding the star back to the list. Yes, the star's radius has caveats but so does many other stars on the list. Like Lithopsian has said previously, UY Scuti's distance is 99% likely to be a huge overestimation and we seem to have no issue with keeping it on the list. The star and it's radius, for all it's potential flaws, should be added back. Faren29 (talk) 10:03, 11 May 2022 (UTC)

Well, if you want to keep it on, keep it on, but that logic points more towards removing UY Scuti from the list rather than retaining Stephenson 2-18. Gaia DR3 will hopefully clear up some of these issues when it is released soon. Another question is, what size is too big? The calculated size of Stephenson 2-18 is already much bigger than is predicted by theory. For me, that makes it unreasonable to include it on the list, especially when there are so many caveats. SpaceImplorerExplorerImplorer (talk) 13:32, 11 May 2022 (UTC)

I agree. We should add it back, with the aforementioned caveats. I think what Faren29 is saying is: “If Stephenson 2-18 is not in the list, then why is UY Scuti in the list?”. The Space Enthusiast (talk) 13:54, 11 May 2022 (UTC)

What is the threshold for excluding a star from the list? If you take the theoretical limit of 1,500 solar radii as a guide, anything above that would be questionable. In that case, why include stars above that limit if there are serious doubts, such as the distance for both Stephenson 2-18 and UY Scuti. Does it make sense to put Stephenson 2-18 on the list based on UY Scuti being on the list if UY Scuti shouldn't be there because it is both over the theoretical limit and has serious question marks over its distance? Big Bang Big Crunch (talk) 09:27, 16 May 2022 (UTC)

We might want to add colored cells and a legend to indicate stars with very uncertain distances. nussun (talk) 07:35, 12 May 2022 (UTC)

Yes, as that would probably be something that people would notice first as well. SpaceImplorerExplorerImplorer (talk) 07:01, 15 May 2022 (UTC)

I really don't see any reason as well to not add St2-18 on the list. While there are caveats regarding its distance and its nature, one should not deny that the large (though absurd) size is based on a direct calculation using the Stefan-Boltzmann law of its known properties at the moment. Clearly unless you have any source that invalidates the previous sources which are the basis of those calculations, you are going nowhere. It is trying to use an argument of ignorance (that we are not sure) against hard mathematics. I should also point out that this 1,500 radius limit was only based on a survey of red supergiants with a sample size of just three. You may argue that there is some theoretical model that defines it, but observations at the moment are still inconclusive regarding the "hardness" of this limit.

Not going towards the same argument as others (pointing to UY Scuti as to why St2-18 should be on the list, which I think is just a fallacious argument by comparison); St2-18 should be there because the math at the moment shows that it should be there, and there are no counter-evidences to suggest otherwise. If you are quite worried about is possibility that it might be an improbable cluster member, a foreground giant, or its properties are overestimated, then we need a source with data to verify this. Unless proven, we should always give the benefit of the doubt to the present sources that we have, and not appeal to the unknown as the basis of why it should not be in the list. There should not have been such a discussion here in the first place. SkyFlubbler (talk) 19:44, 22 May 2022 (UTC)

"If you are quite worried about is possibility that it might be an improbable cluster member, a foreground giant, or its properties are overestimated, then we need a source with data to verify this."

It has already been stated in sources multiple times that the membership is at least doubtful, so I'm not entirely sure what you're talking about. nussun (talk) 09:45, 23 May 2022 (UTC)

Yes, it has been mentioned so many times that a majority of of the only 10 or 11 papers on the star mention it. —The Space Enthusiast (talk) 03:33, 24 May 2022 (UTC)

MY Cephei

Lets discuss MY Cephei and and gauge where it should be placed on the list.

Beaser et al. 2018 gives a luminosity of roughly 155,000 L_☉ and with a temperature of 3,400 K (not mentioned to be its temperature directly but is mentioned in a range of values for the temperature of red supergiants located in NGC 7419), which gives a radius of around 1,138 R_☉. Humphreys et al. 2020 is the other source which gives a temperature and a luminosity. They derive a luminosity of roughly 310,000 L_☉ and clearly give a temperature of 3,000 K, which works out to roughly be roughly 2,061 R_☉, more extreme than Beasor et al. 2018 suggests. Which radii should we use to put in the table or should we use both in the table? Faren29 (talk) 12:41, 19 May 2022 (UTC)

May I note also that 3,400 K is an assumption temperature based on a spectral type of M7.5. Faren29 16:59, 20 May 2022 (UTC)

We have a whole article about this star. Although it has traditionally been treated as having the extreme spectral type M7.5 or so, a recent paper suggests a more realistic spectral class of M3 based on infrared observations. It also gives a correspondingly higher temperature. Although they derive a luminosity, they don't explicit publish it. You can guess from a graph or work it out from other published data, but probably not good enough for Wikipedia's purposes. I'm going to update the article a little, but it won't directly affect the radius. Lithopsian (talk) 18:12, 20 May 2022 (UTC)

So while I was there, I took the opportunity to review the literature for MY Cep, particularly the main references used in the WP article. The spectral class dates from 1974 and isn't seriously re-derived in any of the more recent papers, although there is no reason to doubt that the optical spectrum does correspond to that class. There is a big discrepancy in the luminosities. The distance is fairly well-defined based on several different methods for the containing cluster, including Gaia EDR3 parallaxes for many of its member stars. The difference arises from the analysis method. Davies et al (2020) doesn't explicitly say where it gets its luminosity value from, but it matches that in Davis & Beasor (2017), derived using the traditional magnitude plus extinction plus bolometric correction. For this star, the bolometric correction dominates and the result is highly sensitive to the value chosen. Humphreys et al (2020) uses SED integration which should be more reliable, but is still very sensitive to the extinction. The temperatures from both papers are almost speculative: one is a book value for an M7.5 star, although M7.5 supergiants are basically off the chart; the other is chosen as a blackbody match to an extinction-correction optical spectrum, which is very insensitive to the temperature chosen. Neither is a very good value for the effective temperature, just the temperature corresponding to a blackbody with the size and luminosity of the star. The new paper probably has a more sensible value for an effective temperature. Given the (not published) luminosity and 3,595 K, the radius would be 1,087 R_☉. If anything, we are in a worse position than before, with reasons to doubt all previous estimates but not much we can put into Wikipedia. Lithopsian (talk) 19:05, 20 May 2022 (UTC)

Table 1 contains enough information to calculate luminosity, if we allow calculating radii using the Stefan-Boltzmann law then I don't see why we can't calculate luminosity using these values. nussun (talk) 22:32, 20 May 2022 (UTC)

Table 1 contains enough information to calculate at least six different luminosities. There are hints in the text as to which one is preferred, also the figure 18 chart, but I think it would be hard to call any of it definitive enough to pick a single value to WP standards. The radii come in around 1,100 R_☉ - 1,500 R_☉, but I'm not sure that gets us any closer to a single value for this list. Lithopsian (talk) 16:19, 21 May 2022 (UTC)

I guess for now all we can say is that the radius is roughly somewhere in the range 1,000–2,000 R_☉. nussun (talk) 21:07, 21 May 2022 (UTC)

It really only leaves us to the two values I originally mentioned: 1,138 solar radii from Beasor et al. 2018 or 2,061 solar radii from Humphreys et al. 2020. We will perhaps have to pick the value that is least flawed (if not both). Faren29 (talk) 21:09, 21 May 2022 (UTC)

Which one do we use then? I don't imagine that both are flawed to the point that none of the radii can be added at all because 99% of the radii here have their caveats. Faren29 (talk) 16:28, 25 May 2022 (UTC)

I'm really not sure... VY Canis Majoris (talk) 17:40, 25 May 2022 (UTC)

References

RSGC1

Considering adding stars from RSGC1. There are three papers that give values for these stars: Davies et al. (2007), Fok et al. (2012) and Humphreys et al. (2020). None give a direct radius, however, they give a luminosity and temperature to calculate the radius.

RSGC1-F01:

Davies et al. (2007): 1,436 solar radii
Fok et al. (2012): 1,551 solar radii
Humphreys et al. (2020): 1,530 solar radii

RSGC1-F02:

Davies et al. (2007): 1,499 solar radii
Fok et al. (2012): 1,549 solar radii
Humphreys et al. (2020): 1,128 solar radii

RSGC1-F03:

Davies et al. (2007): 1,167 solar radii
Fok et al. (2012): 1,325 solar radii
Humphreys et al. (2020): 942 solar radii

RSGC1-F04:

Davies et al. (2007): 1,082 solar radii
Fok et al. (2012): 913 solar radii
Humphreys et al. (2020): 1,422 solar radii

RSGC1-F05:

Davies et al. (2007): 1,177 solar radii
Fok et al. (2012): 1,047 solar radii
Humphreys et al. (2020): 1,185 solar radii

RSGC1-F06:

Davies et al. (2007): 885 solar radii
Fok et al. (2012): 979 solar radii
Humphreys et al. (2020): 1,382 solar radii

RSGC1-F07:

Davies et al. (2007): 910 solar radii
Fok et al. (2012): 716 solar radii
Humphreys et al. (2020): 1,006 solar radii

RSGC1-F08:

Davies et al. (2007): 1,145 solar radii
Fok et al. (2012): 1,087 solar radii
Humphreys et al. (2020): 1,150 solar radii

RSGC1-F09:

Davies et al. (2007): 988 solar radii
Fok et al. (2012): 1,230 solar radii
Humphreys et al. (2020): 996 solar radii

RSGC1-F10:

Davies et al. (2007): 931 solar radii
Fok et al. (2012): 954 solar radii
Humphreys et al. (2020): 1,246 solar radii

RSGC1-F11:

Davies et al. (2007): 1,014 solar radii
Fok et al. (2012): 955 solar radii
Humphreys et al. (2020): 1,035 solar radii

RSGC1-F12:

Fok et al. (2012): 1,005 solar radii
Humphreys et al. (2020): 955 solar radii

RSGC1-F13:

Davies et al. (2007): 1,097 solar radii
Fok et al. (2012): 993 solar radii
Humphreys et al. (2020): 1,017 solar radii

RSGC1-F14:

Davies et al. (2007): 698 solar radii
Fok et al. (2012): 588 solar radii
Humphreys et al. (2020): 662 solar radii

RSGC1-F15:

Davies et al. (2007): 340 solar radii

I was wondering which values should we use? Let's discuss. Faren29 (talk) 13:00, 29 May 2022 (UTC)

I generally go with the newest reliable source. Humphreys etal. (2020) analyses a relatively few stars of this type, as do the other papers. The methodology is one that is prone to over-estimates in a few cases, but is robust for most stars. I don't see anything to prefer in the older papers and the estimates overall seem consistent. Lithopsian (talk) 13:25, 29 May 2022 (UTC)

RSGC1 stars F01–F13 have been added with their radii values from Humphreys et al. (2020). Faren29 (talk) 13:41, 29 May 2022 (UTC)

Faren29, could you use {{List of largest stars row}} for these values, since they do not give the radii specifically? It will make err-checking easier in the future. Cheers. Primefac (talk) 17:06, 29 May 2022 (UTC)

Noted. Will do. :) Faren29 (talk) 17:24, 29 May 2022 (UTC)

I suppose the same treatment can be given to the Stephenson 2 and RSGC3 stars and use the radii implied from Humphreys et al. (2020)? Faren29 (talk) 18:20, 29 May 2022 (UTC)

M31 and M33

Numerous M33 and M31 stars were present on the list around a year back and I'm starting to question how many of these can be added back? We have a few already from a 2009 source but these stars were supported with 2016 and 2020 sources. They seem to be computer churned-out results as some of these sources give incredibly extreme radii and it seems that they wouldn't be as reliable as studies dedicated to calculating radii. Any opinions?

https://en.wikipedia.org/enwiki/w/index.php?title=List_of_largest_known_stars&oldid=1042478582 Faren29 (talk) 15:01, 31 May 2022 (UTC)

As usual, I think they were not added back because no one has re-added them; if the source(s) seem reasonable, there shouldn't be any issue with putting them in the appropriate table(s). If someone has issue with them, we will then discuss as is appropriate in such situations. Primefac (talk) 15:38, 31 May 2022 (UTC)

Many of the previously high luminosities have now been disproven in [3] and found to be lower. VY Canis Majoris (talk) 01:02, 1 June 2022 (UTC)

IRAS 05280-6910

IRAS 05280-6910 has two estimates of its radius. Goldman et al. (2016) implies a smaller radius of 1,367 R_☉ from a temperature of 3,400 K and a luminosity of 225,000 L_☉. However, Matsuura et al. (2016) directly gives a larger radius of 1,738 R_☉, which would be preferred. I suppose we should use the radius given by Matsuura et al. (2016)? Faren29 (talk) 14:23, 2 June 2022 (UTC)

Ok, If you wish to, but we need a bit more discussion regarding this. The list may devolve back into a messy one if we don't discuss about which estimate to use, the larger or smaller one.--The Space Enthusiast (talk) 02:10, 3 June 2022 (UTC)

How has this article not been labelled as controversial yet?

I've seen plenty of conflict surrounding this article over time (over inaccurate or outdated radii, whether certain stars should be included in the list, you get the point.), so how is this not a 'controversial article' yet? For example, List of largest empires is labelled as controversial, yet this article is perhaps just as controversial, if not more. Æ is a good character (talk) 09:33, 7 June 2022 (UTC)

I would definetly consider this a controversial article. VY Canis Majoris (talk) 09:49, 7 June 2022 (UTC)

Um... the other article given as an example does not appear to be labelled as controversial. That being said, we have a ton of caveats listed as to why there is so much discrepancy in values. Primefac (talk) 11:58, 13 June 2022 (UTC)

Semi-protected edit request on 30 June 2022

Omarseid2011 (talk) 04:11, 30 June 2022 (UTC) I Need This Page TO Be Editted

Why? The Space Enthusiast (talk) 06:08, 30 June 2022 (UTC)

 Not done: it's not clear what changes you want to be made. Please mention the specific changes in a "change X to Y" format and provide a reliable source if appropriate. Primefac (talk) 07:54, 30 June 2022 (UTC)

Gaia DR3

Gaia DR3 has just been released, so I will be attempting to update the list. VY Canis Majoris (talk) 12:11, 13 June 2022 (UTC)

Thanks, I am currently taking a break from editing.--The Space Enthusiast (talk) 04:26, 14 June 2022 (UTC)

Nussun05, I don't have time to check right now, but did the paper give specific R_☉ values or did you calculate them? Primefac (talk) 10:36, 15 June 2022 (UTC)

They give the radius values. VY Canis Majoris (talk) 10:37, 15 June 2022 (UTC)

How nice of them! Primefac (talk) 10:41, 15 June 2022 (UTC)

Unfortunately many of the radii are erroneous due to the distances being several kpc off from what they should be. VY Canis Majoris (talk) 11:40, 15 June 2022 (UTC)

"Should be"? If the whole point of Gaia was to precisely measure stuff, wouldn't a value different than the historical one be an improvement? Primefac (talk) 11:45, 15 June 2022 (UTC)

Some are several kpc different than what the parallax and Bailer-Jones suggest. VY Canis Majoris (talk) 18:57, 15 June 2022 (UTC)

Again, wasn't that the point of the mission? i.e. shore up values to fix potentially inaccurate values from days gone past. Primefac (talk) 19:05, 15 June 2022 (UTC)

It's not from the past, it's literally disagreeing with other values from the same data. VY Canis Majoris (talk) 20:42, 15 June 2022 (UTC)

I'm with Lithopsian on this one - you're saying that the data from DR3 is conflicting with data from DR3, which makes zero sense. Examples and further explanation are necessary. Primefac (talk) 09:40, 16 June 2022 (UTC)

Says who? Again, give an example and explain what is several kpc different from what. Lithopsian (talk) 19:42, 15 June 2022 (UTC)

Gaia has been known to produce wild and inconsistent values (see here for context and the discussion of these issues.) In summary it makes very poor readings of sources with hivh proper motion and those that lie in highly contaminated regions (like the Milky Way plane, where the vast majority of the stars in this list are). At its very core it still uses the same mechanics as Hipparcos (which itself also has issues to begin with).

I think what is meant here is that the values in Gaia are non-reproducible by other independent measurements and too uncertain to be used, save for some specific contexts. Personally, I take data from Gaia with a grain of salt, and just because it's newer doesn't mean it should supersede distances given by ground-based observations (like VLT, for example) which have a pretty good backing in their values. Unless there is a counterargument to use Gaia and totally trash off older distance estimates, it should only be used as a second option. SkyFlubbler (talk) 10:40, 28 August 2022 (UTC)

Also, specifically for DR3, you can check out this paper for some info about the limitations, caveats, and how to properly use the data. SkyFlubbler (talk) 10:46, 28 August 2022 (UTC)

Biggest object

Actually the biggest star is Noe UY Scuti 37.30.44.160 (talk) 07:58, 9 November 2022 (UTC)

What do you mean? --The Space Enthusiast (talk) 11:17, 9 November 2022 (UTC)

"now"? "not"? Either way, give reliable references, discuss why one particular reference should be used rather than another, possibly at the individual star articles themselves, then whichever ends up biggest is biggest. Lithopsian (talk) 16:08, 9 November 2022 (UTC)

Stephenson 2-18 (again)

The distance to Stephenson 2-18 is already very uncertain although it has been added back to the list a few months ago. Although the arguments to keep it on the list are closer to removing UY Scuti than retaining Stephenson 2-18, retaining St2-18 adds more uncertainty to the list. Due to very high uncertainties in distance, luminosity etc. it would probably make more sense to remove all stars with extreme uncertainties from the list which would also make it more reliable. SpaceImplorerExplorerImplorer (talk) 16:36, 2 October 2022 (UTC)

What do you consider to be "extreme uncertainty"? (please do not ping on reply) Primefac (talk) 18:41, 2 October 2022 (UTC)

For example St2-18's or UY Sct's distance estimate. SpaceImplorerExplorerImplorer (talk) 18:53, 2 October 2022 (UTC)

That's not what I asked, but if we were to extend your line of thinking, UY Scuti's error is ~10%. If we said "anything with >10% error gets nixed" we would remove almost half of this list (the other half being kept largely because we don't have error measurements). I am not advocating for or against this proposal, but I do have to ask the question: is that your intention? Primefac (talk) 08:47, 3 October 2022 (UTC)

What I would consider an 'extreme uncertainty' would be something that would probably be about over 30% or when the difference in multiple distance values are huge (eg. UY Sct's distance measurements that have huge differences). Stars that do not have an at least somewhat certain/clear distance, luminosity, radius etc. could be removed.SpaceImplorerExplorerImplorer (talk) 9:31, 3 October 2022 (UTC)

• Sigh*...Has this already been settled?--The Space Enthusiast (talk) 05:14, 20 October 2022 (UTC)

The data that we have about Stephenson 2-18 is the best that we got so far. I don't see a point of removing it just because it is "too uncertain." SkyFlubbler (talk) 08:00, 20 October 2022 (UTC)

The data that was used was the only data that you could calculate a radius with and relying on one single reference that is extremely uncertain data does not make sense. SpaceImplorerExplorerImplorer (talk) 13:46, 20 October 2022 (UTC)

"relying on one single reference with extremely uncertain data does not make sense"

But that is the best data that we have. That is the only data that we have. It takes more than just being "too uncertain" for it to be thrown out of the window – you need to show an alternative radius estimate. SkyFlubbler (talk) 01:08, 21 October 2022 (UTC)

You can read WP:TRUTH for some idea as to why the reasoning "too uncertain" is not enough. SkyFlubbler (talk) 01:19, 21 October 2022 (UTC)

I agree with SkyFlubber. Stephenson 2-18's 2,150 solar radii estimate is very large (and, absurd), but it's the only one we have right now. There seems to be nothing regarding the radius of this star since Negueruela (2013), though I may be wrong.--The Space Enthusiast (talk) 09:41, 21 October 2022 (UTC)

Obviously if it is the only data it will be the best data. Although the problem I see with it is that it is a ‘low-quality’ estimate and it is certainly not the best data we have for luminosity. The lower luminosity would give a way smaller estimate (still can’t be added to the list since the size would not come from one reference), the temperature is also most likely correct. SpaceImplorerExplorerImplorer (talk) 08:11, 16 November 2022 (UTC)

How is it a low-quality estimate?—The Space Enthusiast (talk) 01:06, 19 November 2022 (UTC)

You asked the same question six months ago, and I don't expect the answer to have changed any. Primefac (talk) 07:56, 19 November 2022 (UTC)

That is why I put it in quotation marks, the estimates for the other stars while having high uncertainties are at least more reasonable and that of St2-18 is not (at least the luminosity is very extreme for its low temperature). SpaceImplorerExplorerImplorer (talk) 10:34, 19 November 2022 (UTC)

You cannot just dismiss the estimate just because you think it is wrong. As per WP:TRUTH: Wikipedia only reports what the reliable sources say; it does not publish what its editors just believe is true. SkyFlubbler (talk) 11:03, 19 November 2022 (UTC)

Based on its definition of what counts as a reliable source basically anything that is a published independent paper could be one even with ridiculous values. SpaceImplorerExplorerImplorer (talk) 13:21, 19 November 2022 (UTC)

See WP:Verifiability, not Truth. The Space Enthusiast (talk) 13:37, 19 November 2022 (UTC)

That is what I looked at and saying “It does not publish what editors just believe is true” does make sense although again it is what counts as a ‘reliable source’ that does not make sense. I already said one of the reasons above. SpaceImplorerExplorerImplorer (talk) 13:45, 19 November 2022 (UTC)

The reasoning "Stephenson 2-18 is more uncertain than other stars, therefore we should dismiss it," is a fallacious appeal to ridicule. It is verifiable, and again, unless you can provide a specific number that tells another estimate, you cannot just dismiss Stephenson 2-18's estimate as invalid, no matter how ridiculous it may look to you. SkyFlubbler (talk) 11:13, 19 November 2022 (UTC)

^This argument sums up everything. The Space Enthusiast (talk) 12:14, 19 November 2022 (UTC)

Based on that you could also add a star that is 10,000 solar radii in one reference and that has no other sources for anything that has its size or that has anything that you can calculate it’s size with. SpaceImplorerExplorerImplorer (talk) 13:18, 19 November 2022 (UTC)

That size estimate will almost certainly get designated as spurious. The Space Enthusiast (talk) 13:23, 19 November 2022 (UTC)

That’s true although with that you could say the same with Stephenson 2-18. SpaceImplorerExplorerImplorer (talk) 13:31, 19 November 2022 (UTC)

Not necessarily. Check the comments of SkyFlubbler for that and there are still arguments that support St2-18’s membership. The Space Enthusiast (talk) 13:36, 19 November 2022 (UTC)

I did look at them and I was talking about extreme inaccuracies of the luminosity and not just about it being uncertain because apparently it is ‘not a reason to remove it’ which can almost make sense although you could say that with lots of stars that are usually dismissed that also have a similar size in the reference. It just simply is impossible for a star to be 440,000 solar luminosities and 3,200 K at the same time and again there I am not talking fully about the uncertainties, it is just a fact. SpaceImplorerExplorerImplorer (talk) 13:53, 19 November 2022 (UTC)

It just simply is impossible for a star to be 440,000 solar luminosities and 3,200 K - I will be honest, it has been a while since I have looked at solar physics equations, so I ask this genuinely looking to refresh my memory - why is this impossible? Primefac (talk) 17:32, 19 November 2022 (UTC)

The luminosity surpasses the Humphreys-Davidson limit for a red supergiant that luminosity is only possible in stars with a much higher temperature. SpaceImplorerExplorerImplorer (talk) 17:56, 19 November 2022 (UTC)

The HD limit is ~5.8; Stephenson 2-18 is at 5.64, so the assertion that 440,000 L_☉ surpasses it is already false. Primefac (talk) 18:04, 19 November 2022 (UTC)

That estimate for the HD limit being 5.8 is from 1979 and is probably also the first estimate of it. Hardly any supergiants have any good estimations (from multiple references) that surpass ~350,000 solar luminosities. Also another thing is that it far surpasses the Hayashi limit of 1,500 solar radii which again hardly any good estimates of stars surpass that. Another thing is that 3,200 K or an M6 spectral type in general is very low for a star with a luminosity that high, most stars that are around the Hayashi limit are M3 stars and not M6 stars. SpaceImplorerExplorerImplorer (talk) 18:36, 19 November 2022 (UTC)

The 1,500 Rsol limit was based on the average of 3 star sizes. The Space Enthusiast (talk) 01:51, 20 November 2022 (UTC)

That is true and I do agree that it is a vague estimate. Although as I stated above, the temperature is very low for a star that large. And again St2-18 has a more reliable luminosity estimate (90,000Lsun) which if the temperature is correct, it would be a lot smaller. Based on its spectral type it would be 3,400 K which is relatively similar to the current known temperature of it. SpaceImplorerExplorerImplorer (talk) 07:11, 20 November 2022 (UTC)

Significant digits

A number of the values in this article use significant digits far beyond what is necessary. For example:

1,279.8291+20.4064
−122.9196

For Wikipedia purposes, this is an extreme level of pedantry because the extra digits don't add any meaningful accuracy to the data. It could more easily be communicated as:

1,280+20
−123

Isn't that more readable? Praemonitus (talk) 15:18, 24 November 2022 (UTC)

Can't argue with that. Primefac (talk) 18:23, 24 November 2022 (UTC)

Semi-protected edit request on 19 December 2022

Add Stephenson 2 DFK 49 (Stephenson 2-11).

Solar radii for Stephenson 2-11 could be:
1074 solar radii
884 solar radii
1,300 solar radii 122.57.152.142 (talk) 06:31, 19 December 2022 (UTC)

 Not done: it's not clear what changes you want to be made. Please mention the specific changes in a "change X to Y" format and provide a reliable source if appropriate. This star has been excluded from the list on the basis that stars with a range of possible radii are listed by the lowest value. The lowest value in this case is below 1,000 R_☉. Lithopsian (talk) 13:46, 19 December 2022 (UTC)

But stars like UU Pegasi are below 1000 solar radii and they are probably not well known 122.57.152.142 (talk) 22:29, 19 December 2022 (UTC)

Other stuff exists is officially not a reason to add yet more, but maybe I'm wrong about the cutoff being at 1,000 R_☉. Either way, an edit request needs to be set up with a description of what you want to have added to the article, not just a general "how about this star?". Maybe sit tight and see if one of the more regular editors comes along to clarify what the cutoff should be now. Lithopsian (talk) 13:58, 20 December 2022 (UTC)

You are correct, we decided a year or two back that 1000 would be the cutoff. Primefac (talk) 02:04, 22 December 2022 (UTC)

References

Remove all stars with article stubs/no articles for ease of access

Stars not particularly not well known and without their own articles are cluttering up the list. A potential suggestion would be to improve ease of access to well known stars like VY Canis Majoris or UY Scuti by removing obscure stars with very short or no articles associated with them Æ's old account wasn't working (talk) 09:52, 10 April 2023 (UTC)

There is already a section for smaller stars that are well-known. I wouldn’t see much point in removing obscure stars (unless the radii are inaccurate) since most are not well-known and that would delete most of the list, including 4 sections. SpaceImplorerExplorerImplorer (talk) 06:27, 11 April 2023 (UTC)

Ah. Forgot to mention the caveat of having three-quarters of the list deleted because their stars had no articles. Good pickup. Still, take Stephenson 2 DFK 1, where it LITERALLY SCREAMS THAT IT'S PROPERTIES (radius, distance to our sun, membership in cluster) [could] BE INACCURATE. That might be a headache in the future. Æ's old account wasn't working (talk) 09:56, 11 April 2023 (UTC)

Stephenson 2 DFK 1’s properties are likely very inaccurate. Not only does the uncertainty in the distance result in a ridiculous error in the radius (I tried to see what that uncertainty would result in with an extinction of 10 and the distance with its uncertainty with the Gaia method and got to 1,459+722
−727 R_☉) but its luminosity is also much higher than the newer Humphreys-Davison limit of 5.5 in the Milky Way in Davies & Beasor (2020) and the ~1,500 R_☉ limit (the limit is only based on the average radius of three stars although using the more reliable radii, it would still make sense e.g. UW Volantis which might be 1,426 R_☉, although that value comes from Gaia DR3 and might not be fully accurate). SpaceImplorerExplorerImplorer (talk) 10:32, 11 April 2023 (UTC)

For the record we are at a midpoint as far as "general practices" go (see WP:CSC for more); basically we don't have a list that is all notable objects, but we also do not have a list of all non-notable objects. We're somewhere in the middle, so it's up to a local consensus to determine whether or not to keep the redlinked items. Given that we have less than 200 Milky Way stars on the main list, I am inclined to keep them all. Primefac (talk) 09:38, 14 April 2023 (UTC)

Inaccurate radii on the list

There are clearly inaccurate radii on the list that should be removed which we have discussed before, I will mention two of them: UY Scuti and Stephenson 2 DFK 1 (and yes, we have discussed this object many times by now). First, UY Scuti, is clearly using an outdated distance estimation, which could mean that its upper radius estimate is spurious. The lower radius estimate is derived from a questionable logL of 5.00 which is exactly the same as others in the paper, this luminosity could also be considered outdated. Second, St2D1, which we have discussed many times, and the arguments of others the last time were based on WP:TRUTH. The limit for a star's radius is 1,500 R_☉ and can be proven with Gaia DR3's accurate and precise radii in a very large dataset, where the largest entry is UW Volantis at 1,426 R_☉. Gaia DR3 also has many other entries above 1,000 R_☉, but none above 1,500 R_☉. Also, the revised Humphreys-Davidson limit is ~316,000 L_☉ in Davies & Beasor (2020), where it states "No matter how we slice the sample, in all cases we see a definite cutoff at log(L_max/L_☉) ≃ 5.5. In the total (K0+) sample and the M0+ subsample, we see overall luminosity distributions which are very similar in shape, and which match the observed II-P distribution rather well." This also applies to the Milky Way and not just the Magellanic Clouds, this is why I stated that it just simply is impossible for a star to be 440,000 solar luminosities and 3,200 K. Also, there is already a much more reasonable luminosity of 90,000 L_☉, which seems to be the only somewhat reliable one since the 440,000 L_☉ estimate seems to be unreliable for the reasons I have already mentioned and the 630,000 L_☉ estimate is likely unreliable due to doubt on its membership and other reasons mentioned in the paper that has that estimate. This is why those stars should be removed. SpaceImplorerExplorerImplorer (talk) 17:11, 11 July 2023 (UTC)

WP:NOTRIGHT. Lithopsian (talk) 18:14, 11 July 2023 (UTC)

Indeed. SpaceImplorerExplorerImplorer 18:30, 11 July 2023 (UTC)

Why are there so many people that are sure that Stephenson 2-18 (DFK 1) is the largest star? It’s source is very inaccurate and quite old. Atlantlc27Lol (talk) 19:45, 11 July 2023 (UTC)

Because everyone checks Wikipedia without bothering to read the papers or wonder if it may be inaccurate. This is why the page should probably be deleted, it only serves as fuel for sensationalism and brings the public further from the truth and actual science. VY Canis Majoris (talk) 19:55, 11 July 2023 (UTC)

That is true. I have also seen you mention that the low luminosity estimate is inaccurate which I do agree with although the highest one is only relevant if it is in the cluster (which it is not) and for other reasons mentioned in the paper, the one used for the radius has a huge uncertainty, and despite being the most accurate one, it is practically meaningless and would be extraordinarily extreme. I have tried to calculate the luminosity with multiple fluxes and the extinction was somewhat unclear so I had to assume one based only on the K magnitude and got to a logL of 5-5.6, where most of my measurements were in the range of logL 5.3-5.54, if I remember it properly. SpaceImplorerExplorerImplorer 05:26, 12 July 2023 (UTC)

I have attempted to measure the luminosity again and got to 277,000+284,000
−137,000 L_☉, using the lower distance in Distances to 1.47 billion stars in Gaia EDR3 since it is almost certainly a foreground object and it could potentially be more accurate than the other one as it doesn’t only use parallax. The extinction is unfortunately unclear and could lead to a much higher uncertainty. I have also tried to get to the radius, when trying to correct the 2MASS J-K magnitude, I got to ~3500 K and then, with the luminosity a radius of 1,400+790
−400 R_☉. This could mean that, despite the enormous uncertainty, St2D1 might be in the range of a regular red supergiant (still very possible that it is just another red giant) to a VY CMa-like star. SpaceImplorerExplorerImplorer 10:20, 12 July 2023 (UTC)

These values are still WP:OR and can't be used to make an argument. VY Canis Majoris (talk) 15:38, 12 July 2023 (UTC)

I was just mentioning it. There have been no proper arguments for or against what I said in the beginning other than maybe Lithopsian’s mention of WP:NOTRIGHT. SpaceImplorerExplorerImplorer 15:54, 12 July 2023 (UTC)

There have been quite a few papers mentioning both UY Scuti and Stephenson 2 DFK 1 lately, such as these 2:https://arxiv.org/abs/2304.09222 and https://arxiv.org/abs/2210.06514. The first paper mentions both stars on page 3, while the second paper mentions them on page 17. They might have chosen these stars due to their media attention, but I believe these constitute significant mentions of these 2, which are helpful for their notability. The Space Enthusiast (talk) 20:16, 11 July 2023 (UTC)

I have seen the first one and found it quite funny that they called it ‘Stephenson 2-18’, which is clearly from media attention and/or Wikipedia. Also for the other one, where is St2-18 mentioned? I can’t find it. Also, I have seen the first one and it only mentiones it for its possibly high luminosity and nothing else. SpaceImplorerExplorerImplorer 05:38, 12 July 2023 (UTC)

I think our copies of the paper are different, so make sure to search the other pages. The Space Enthusiast (talk) 15:43, 12 July 2023 (UTC)

I have to once again warn about the use of Gaia spacecraft data. This satellite still uses pretty much the same technology has Hipparcos and is unreliable in many cases. This highlights some of the issues, with cross-contamination being a major one, and is pretty evident is a star is surrounded by other bright stars or is in a dense environment (like UY Sct or St2-D1).

It would be unaccounted for if we have to use this data, and this might constitute WP:OR. This should be taken with a grain of salt and await for any systematic peer reviewed paper that publishes or affirms the accuracy of the data, which includes UY Sct and St2-D1. SkyFlubbler (talk) 15:51, 14 July 2023 (UTC)

RfC discussion on Stephenson 2 DFK 1

I have raised yesterday (forgot to add it to here immediately, apologies!) an RfC discussion regarding this star at its talk page here: Talk:Stephenson 2 DFK 1#RfC: The radius of Stephenson 2 DFK 1, which I highly recommend for you to check out and contribute, so that hopefully we can make a proper resolution to this issue plaguing this list for years now. Thanks in advance. Regards! SkyFlubbler (talk) 05:47, 20 August 2023 (UTC)

Radius of VX Sgr.

From what I know, the 853 R_☉ size estimate for this star is not the scientific consensus and the star is genenrally considred to be much larger. Are there any other recent size estimates that suggest a similar radius? Diamantinasaurus (talk) 15:39, 13 September 2023 (UTC)

See the values and references in the linked star article. The value from the 2020 paper is calculated from an angular diameter and distance, although the article doesn't seem to make this clear, so it may not be directly comparable with radii corresponding to effective surface temperatures. DeBeck (2010) gives real outlier radii for many stars, probably best avoided when there are more recent sources. Lithopsian (talk) 18:48, 13 September 2023 (UTC)

Yeah. This paper has a 1891 R_☉ Betelgeuse. Diamantinasaurus (talk) 20:50, 13 September 2023 (UTC)

Temporarily large

V838 Monocerotis and Eta Carinae have recently been added to this list. They are relatively small stars (~350 and ~250 R_☉, respectively) but during a brief period of expansion ballooned out to well larger than the largest stars. I have two questions, one general and one for Eta Carinae. The first is - do we want to include these "briefly huge" stars on the list? Second (and this might need its own subsection) I am not overly thrilled with the fact that the Eta Carinae values are estimated (since the Great Eruption happened in the 1800s and the authors of the various papers make a lot of assumptions). Primefac (talk) 10:12, 18 September 2023 (UTC)

We should add a specific section for these events and the largest they got. Atlantlc27Lol (talk) 22:53, 21 September 2023 (UTC)

Revisisting the list (again)

Hello. I wanted to let you know that I have been trying to rewrite the list in one of my sandbox pages (maybe as a possible workpage or not, in case I may move this page), so it can be more organized by also including like legends (or keys) for the list and an overview as a brief explanation for very large stars by radius (and temporarily ones like for LBVs or LRNs). Is anyone interested there? Regards—ZaperaWiki44^{(✉/Contribs)} 15:53, 4 October 2023 (UTC)

You might want to read through MOS:COLOR and our archives (e.g. 1, 2) for why we don't have colour-coding in our tables any more. Primefac (talk) 09:19, 5 October 2023 (UTC)

MSX SMC 055 and [W60] A72

Those two stars were removed due to supposedly being foreground stars. However, the source for those two stars does not suggest the two stars are foreground. This source doesn't consider [W60] A72 foreground star either. While the Gaia parallax is noisy, it is very low and even negative in the case of the LMC star. What was used to suggest that the two stars are foreground? Diamantinasaurus (talk) 10:16, 8 October 2023 (UTC)

The radius calculated by Gaia uses a distance calculated with spectra, not parallax. I have downgraded A72 to a more believable radius anyway, I will try to do the same with the other one as well. SpaceImplorerExplorerImplorer 11:22, 8 October 2023 (UTC)

Well, the source for it being 1,441 times larger than the Sun has even more absurd estimates for some stars (WOH G64 is 13,100 times larger than the Sun there and WOH S264 is 2,500 times larger). And yes, I know that the distance uses pectra. MSX SMC 055 is also a Mira with a pulsation period of over 1800 days. If I remember correctly, Miras with high periods are usually very luminous too. Diamantinasaurus (talk) 11:38, 8 October 2023 (UTC)

The absurd radii are a minority though and a long pulsation period does not always mean it is VY CMa-like. It might also be worth avoiding radii larger than that of WOH G64 as it has been considered to be the largest known and is just above the limit that has been seen, with well-measured radii in the Large Magellanic Cloud. SpaceImplorerExplorerImplorer 11:46, 8 October 2023 (UTC)

Well, there's still 6 of these in the LMC alone. Also, can you add the reference for 055? It isn't there. Diamantinasaurus (talk) 14:12, 8 October 2023 (UTC)

Standards for the list

The recent edit warring has made it clear we need some sort of standard for the list. Which papers do we include radii from, and how do we select which paper to use for the radius of an individual star? We might want to create a workpage for this VY Canis Majoris (talk) 08:38, 9 October 2023 (UTC)

Standards for what should be included on the list should be consistent with better, high-quality observations, such as the estimates for WOH G64 and VY CMa (which also show a cut-off at 1,500 R_☉. Estimates that are outliers, such as that of UY Sct should be examined more thoroughly before being added and in the case of this star, the distance seems outdated and a newer noiseless Gaia EDR3-derived distance has a lower uncertainty and is much lower, indicating that it is smaller. Stars with huge uncertainties in radius-related measurements like St2D1 and NML Cyg should be avoided for obvious reasons. All this is to try to prevent absurd or highly inaccurate radii to be added and to prevent tiring discussions like many in the past. A workpage would be very useful and it would probably make sense to wait before adding or discarding any controversial stars until much better measurements exist. SpaceImplorerExplorerImplorer 18:49, 9 October 2023 (UTC)

Would it be possible to add some kind of an index showing how reliable a star size estimate is or would that be WP:OR? Diamantinasaurus (talk) 17:59, 11 October 2023 (UTC)

The reliability of radii or L/T_eff measurements are not always mentioned in papers, although the reliability can be seen by the looking at the values and applying previous limits from better observation to it, which is vaguely on the list already but does unfortunately allow ridiculous radii to be added. SpaceImplorerExplorerImplorer 18:09, 11 October 2023 (UTC)

Why are the lists seprated based on the galaxy?

For example, why are the LMC and SMC stars in a separate section from the M31 and M33 stars? Diamantinasaurus (talk) 14:22, 13 October 2023 (UTC)

It makes the list less messy (especially with references) and galaxies have different properties which can lead to stars being different in radius. It wouldn't be necessary to have a bigillion sections for individual galaxies though, so they are grouped like how they are on the list now. SpaceImplorerExplorerImplorer 14:44, 13 October 2023 (UTC)

MSX LMC 891

In Groenewegen & Sloan 2018 this RSG is stated to be the coldest one with the spectral type M7 and a temperature of 3129 K (corresponding to a radius of 1635 R_☉ using the luminosity in the table). But in the table with the stellar parameters the RSG's temperture is 3400 K instead (corresponding to a radius of 1385 R_☉). Why are the temperatures different and do we add the larger radius to the list as well (the smaller one is already there)? Diamantinasaurus (talk) 20:31, 14 October 2023 (UTC)

V766 Centauri Aa

Recently I've added V766 Centauri Aa and I've downgraded it to 1,060—1,160 R_☉ (1,110±50 R_☉) but it seems that these values are too large for a yellow supergiant and that it would be much cooler if it was that large. SpaceImplorerExplorerImplorer (talk) 15:50 24 December 2021 (UTC)

Sextans A stars

I just added some Sextans A stars, but the radii seem really suspicious. And there is a 1200 K star somehow. Should we remove them? Diamantinasaurus (talk) 17:20, 22 October 2023 (UTC)

SextansA 125 is very close to [SC82] PM1 (foreground star around 1.4 kpc away). Both have almost identical J, H and K magnitude but 125 has 22.63 Imag while PM1 Imag is 15.91. Are they the same star? Diamantinasaurus (talk) 18:32, 22 October 2023 (UTC)

I removed them due to having very extreme radii (indicating that they would be RSGs) but really low temperatures, the Hayashi limit is 3500 K and a star lower than that with a very high luminosity would no longer be in hydrostatic equilibrium and would likely not be able to exist in that state permanently. Some had absurdly high luminosities that exceeded the Humphreys-Davidson limit for RSGs as well so I had to remove them. SpaceImplorerExplorerImplorer 06:51, 24 October 2023 (UTC)

M51 OT2019-1

This transient is an ILRT (a class of SN impostors). This paper finds a radius of 380,000,000,000,000 centimetres (5,500 R_☉) for the LBV at it's optical peak. Do we add it (and 1843 Eta Carinae) to the list or not? Diamantinasaurus (talk) 13:10, 12 October 2023 (UTC)

It appears to be the only source with any radius mentioned. I would wait until further observations happen with newer radius measurements. SpaceImplorerExplorerImplorer 16:51, 12 October 2023 (UTC)

Well, the transient ended in 2019 so there probably won't be a lot of papers made about it anytime soon. The estimated luminosity of this star during the outburst falls within the range of those of SN impostors and the estimated temperature is normal for LBV outbursts too, so the estimate is probably reliable. Diamantinasaurus (talk) 14:18, 13 October 2023 (UTC)

Since these are temporary radii, it would make sense to put them in a different section. SpaceImplorerExplorerImplorer 14:46, 13 October 2023 (UTC)

Should we make a new section of these types of sizes/estimates? Atlantlc27Lol (talk) 19:18, 7 November 2023 (UTC)

I already did that. Diamantinasaurus (talk) 19:20, 7 November 2023 (UTC)

Remove NML Cyg?

The effective temperature of 3250 K is purely based on the assumption that it is an M6 giant, which it is not and the effective temperature of an M6 giant is only from old fluxes and interferometry of some stars, the effective temperatures measured can be quite a lot different to newer and more accurate ones. It is even disfavoured by Zhang et al. (2012) and they adopt a T_eff of 2500 K, which is obviously a ridiculous estimate. Furthermore, Gaia DR3 gives a more believable temperature of ~3440 K. SpaceImplorerExplorerImplorer 10:10, 8 November 2023 (UTC)

Gaia DR3 is not a reliable source for temperature here, but another source does give 3,300 K but only uses luminosity in a diagram. VY Canis Majoris (talk) 11:56, 8 November 2023 (UTC)

The star should still be removed though, since the temperatures for the spectral types were estimated only from the average ones of the stars in the paper which often didn't have an accurate effective temperature and were offset from newer and more accurate effective temperatures for the same stars by more than 100 K. SpaceImplorerExplorerImplorer 12:36, 8 November 2023 (UTC)

But a newer source still gives a 3300 K temperature for NML Cygni. Diamantinasaurus (talk) 14:08, 8 November 2023 (UTC)

Doesn’t really change the accuracy of Zhang et al. (2012) though, the paper you cited still seems to partially rely on old spectra. SpaceImplorerExplorerImplorer 15:26, 8 November 2023 (UTC)

Still better than Gaia DR3 which relies on purely optical extremely low resolution spectra. VY Canis Majoris (talk) 21:48, 8 November 2023 (UTC)

I’m not relying on Gaia DR3.SpaceImplorerExplorerImplorer 07:04, 9 November 2023 (UTC)

I agree, we should remove it. There is also already an estimate for 1183 solar radii. Atlantlc27Lol (talk) 15:01, 11 November 2023 (UTC)

That uses an outdated distance and the same paper gives unreliable values for other stars like Betelgeuse. VY Canis Majoris (talk) 17:36, 11 November 2023 (UTC)

That uses an outdated distance and the paper contains some questionable estimates, such as 853 R_☉ VX Sgr, 1342 R_☉ IRC +10420 and even ~2000 R_☉ Betelgeuse. Diamantinasaurus (talk) 17:56, 11 November 2023 (UTC)

Unfortunately, the estimate is also inaccurate and uses an effective temperature very inconsistent with its spectral type. SpaceImplorerExplorerImplorer 19:19, 11 November 2023 (UTC)

Oh, ok. Then if the 1183 SR size is inaccurate, then I agree we should remove it altogether. Atlantlc27Lol (talk) 19:30, 11 November 2023 (UTC)

Can’t we just remove Stephenson 2 DFK 1 (2-18) already?

It has a 50% uncertainty, the estimate is very old, unreliable, its way over the theoretical limit of 1,500 SR, there are newer estimates saying it is smaller and has a smaller luminosity, and speaking of luminosity, Stephenson 2 DFK 1’s luminosity is over the theoretical 500,000 solar luminosities for a red supergiant, and it might not even be in the cluster Stephenson 2, and the only reason i’m not removing it right now is because the people that say it is will come after me and revert it. I believe WOH G64 might be the largest though. Atlantlc27Lol (talk) 18:09, 12 August 2023 (UTC)

Unfortunately, they will probably not remove it due to WP:NOTRIGHT until there is a new source. Also, the luminosity limit is logL ≈ 5.5 (~320,000 L_☉) which is consistent with the highest highly reliable luminosity estimates (or up to ~5.6 (~400,000 L_☉) for K-type supergiants based on the same method as logL ≈ 5.5) SpaceImplorerExplorerImplorer 17:05, 14 August 2023 (UTC)

This conversation sparks up once every few months and it always comes to a stagnation. When will you realise that until we have a new source to work with, there is nothing we can do about it? Enough with it, it is incredibly tiring. Faren29 (talk) 00:12, 16 August 2023 (UTC)

I might be mixing it up with something else, but wasn’t there a few in the 2010s? Atlantlc27Lol (talk) 19:56, 18 August 2023 (UTC)

Since 2021, I have been looking for papers mentioning it that give luminosity and effective temperature or the radius but could not find any papers. There are also no good luminosity estimations so far. Actually, if the noiseless photogeometric distance is accurate, it would likely have a much lower extinction of A_V = ~7.149, although it comes with very high uncertainty, that would possibly be consistent with it having a luminosity similar to that of a luminous carbon star (obviously it isn’t one). Using assumed extinction, it is in the range of being a regular red supergiant to being VY CMa-like. However, all that would be WP:OR and/or WP:SYNTHESIS, so it can’t be added to Wikipedia. SpaceImplorerExplorerImplorer 07:16, 19 August 2023 (UTC)

Yes, that is true. But if we can’t remove St2-18, isn’t it just better to delete the entire list if even stars above 6,000 R_☉ (yes, such estimates exist) can be added without being removed because there are no other estimates out there? SpaceImplorerExplorerImplorer 07:08, 19 August 2023 (UTC)

Exactly. Once I looked in the previous revisions on this page and they had WOH G17 here at 2,955, and RS Menase somewhere at 4,500 SR. Whats the point of this page if alot of things here are blatantly unreliable? Atlantlc27Lol (talk) 20:16, 19 August 2023 (UTC)

You will notice that those blatantly unreliable values are no longer on the page. We have a note for St2-18 indicating that there are large uncertainties, but we do have references. Primefac (talk) 10:07, 24 August 2023 (UTC)

Still does not mean you should keep it. Just because it seems more reliable, it is likely spurious. Standards for stellar radius inclusion do not use scientific papers that have things like the limit which use reliable, carefully constrained radii instead of a clearly spurious estimation. If you want to have standards, then use scientific papers. SpaceImplorerExplorerImplorer 14:55, 24 August 2023 (UTC)

Note: there is an ongoing RfC discussion regarding this object which I think would further dive into this issue. SkyFlubbler (talk) 05:28, 20 August 2023 (UTC)

It's unfortunate that there's only one estimate for its size, so we can only focus on that radius of 2,150 solar radii until improved analysis is made in the future.

It's best to keep on hanging. Eric Nelson27 (talk) 18:45, 17 November 2023 (UTC)

Its radius should remain as a note rather than an actual entry on the list to keep general accuracy and not make the list as misleading. SpaceImplorerExplorerImplorer 18:56, 17 November 2023 (UTC)

NML Cygni

Moved this discussion to the talk page. Seems like this paper has a radius of ~1450 R_☉ but I don't think that's for the star's photosphere though. Another paper derives a temperature of 3300 K and uses a luminosity from literature (which most likely is the 270000 L_☉ goijg by the H-R diagram, corresponding to a radius of 1590 R_☉. I'm not sure that radius can be used though (also it's probably a bit too large as well). Diamantinasaurus (talk) 20:50, 21 November 2023 (UTC)

I would keep it off the list for now. 3300 K uses old spectra anyway and 1450 R_☉ is probably for the surrounding disk rather than the actual photosphere. SpaceImplorerExplorerImplorer 07:23, 22 November 2023 (UTC)

What's wrong with old spectra? The star's spectrum shouldn't have changed much and there hasn't been significant improvement in spectrograph technology. Also, NML Cygni is very likely an extreme star but the temperature is practically unknown and also hard to measure due to the complex circumstellar environment. VY Canis Majoris (talk) 08:36, 22 November 2023 (UTC)

Alright then. SpaceImplorerExplorerImplorer 08:46, 22 November 2023 (UTC)

It is probably similar to VY CMa in size though. Diamantinasaurus (talk) 15:10, 22 November 2023 (UTC)

Probably that or smaller, however there is no accurate radius yet, so it wouldn't really make sense to keep it on the list. SpaceImplorerExplorerImplorer 16:07, 22 November 2023 (UTC)

Also there is extinction. 10.7 magnitudes of it. Diamantinasaurus (talk) 16:21, 22 November 2023 (UTC)

I now got to 1,350+229
−195 R_☉ for NML Cyg based on Zhang et al. (2012)'s distance and a long-baseline interferometry-derived angular diameter in the CHARM2 survey, although this would be WP:SYNTHESIS so don't use it on the list and since this comes from a large-scale survey and is mentioned to be a complex source, it might be inaccurate anyway. SpaceImplorerExplorerImplorer 17:47, 22 November 2023 (UTC)

I doubt that angular diameter is accurate either, as I said the circumstellar environment of NML Cygni is very complex, so measuring the size of the star is near impossible. Even the best the papers give us are estimates because the star is simply not optically resolved. VY Canis Majoris (talk) 20:19, 22 November 2023 (UTC)

Indeed. SpaceImplorerExplorerImplorer 20:35, 22 November 2023 (UTC)

M33 RSG

LGGS J013312.26+310053.3 is a RSG (probably a K-type one) in M33 (also the brightest RSG in terms of apparent magnitude). It has an estimated luminosit of 10^5.76 L_☉, way above the H-D limit (HR 5171 had a similar estimated luminosity but a recent paper suggests the star is closer than previously thought). The star's fluxes from SIMBAD seem to agree with the estimated luminosity. I check Gaia DR3 and it did turn out that the source is probably two objects but the second one is around a hundred times dimmer than the RSG. The star is also not a foreground star either. Is there any reason for the high estimated luminosity?

I got an even higher estimated luminosity for the K-type star RX J0132.4+3036 located in M33 (~740,000 L_☉ and that most likely was an underestiate), but the proper motion is way too high for it to be actually a member of that galaxy. Diamantinasaurus (talk) 13:52, 25 November 2023 (UTC)

Likely low quality observations, another luminosity of 805400 L_☉ was measured for the star and the paper mentioned that it was likely to be a supergiant. Don't keep it though, since large-scale surveys tend to give absurd measurements for extreme stars like this one. SpaceImplorerExplorerImplorer 14:15, 25 November 2023 (UTC)

The source for that higher luminosity used WISE photometry which resulted in some very high overestimates (such as 1,230,000 L_☉ LGGS J04539.99+415404.1).

The V-band magnitude of J013312.26 is 16 (making it even brighter than M33-013406.63), the M33 extinction is 0.8 magnitudes and the distance modulus is 24.6 resulting in an estimated absolute visual magnitude of -9.4, suggesting a very high luminosity.

The K-band magnitude is 12.43. It's even brighter than the largest M33 star in this list by 0.17 magnitudes (which is also colder as well). Even RX J0132.4+3036 is dimmer by 0.06 magnitudes (but it's V-band magnitude is 15.571). Diamantinasaurus (talk) 14:34, 25 November 2023 (UTC)

Seems like it's two (or even three) different stars in HST. I'm not really sure though. Diamantinasaurus (talk) 18:01, 25 November 2023 (UTC)

New format

I've been experementing with a new way to state the methods to get radius, it separates photometric and spectroscopic luminosity and temperature estimates and included methods for distance. There may be too many columns, since I also included things like the stellar association or cluster each star belongs to. User:Nussun05/List of largest stars 2.0 VY Canis Majoris (talk) 07:32, 23 November 2023 (UTC)

I wouldn’t put all of them in the same table though, since stars in other galaxies generally have different metallicities, which can affect their effective temperatures and therefore radii and it makes the list less messy as well. SpaceImplorerExplorerImplorer 07:46, 23 November 2023 (UTC)

It makes it easier to compare all the stars, and to instantly see which star is at the top. VY Canis Majoris (talk) 14:07, 23 November 2023 (UTC)

At least put transient events like SPIRITS 14atl in a different section. SpaceImplorerExplorerImplorer 14:10, 23 November 2023 (UTC)

That's a RSG in M83. Diamantinasaurus (talk) 21:26, 23 November 2023 (UTC)

They are not transient events, they are normal red supergiants. They just happened to be detected in a survery looking for transient events, I think these red supergiants might have undergone some outburst or something. VY Canis Majoris (talk) 05:38, 24 November 2023 (UTC)

Nevermind, the normal pulsation triggered a transient alert. VY Canis Majoris (talk) 13:21, 24 November 2023 (UTC)

I agree. I think it’s better if we have all the stars in one section, but I do agree with putting temporary sizes in different sections. Atlantlc27Lol (talk) 22:04, 27 November 2023 (UTC)

Noisy parallaxes?

The Gaia DR3 parallaxes used here for some stars (like CM Vel) seem to be very noisy. Should these stars be removed? Diamantinasaurus (talk) 19:50, 21 November 2023 (UTC)

They rely on spectra rather than parallaxes, however the spectra are very low-resolution (50x50 pixels) and the radii only rely on two magnitudes, which could lead to misleading values. The distances also appear to be highly inconsistent with noiseless parallaxes derived from the same data. SpaceImplorerExplorerImplorer 20:18, 21 November 2023 (UTC)

HV 888 has is a foreground star 21 kpc away according to the spectra (with a radius of ~760 R_☉), so I'm not really sure if they are reliable. Diamantinasaurus (talk) 18:50, 23 November 2023 (UTC)

There are some seemingly accurate properties for some stars, but others that have surrounding areas that could interfere with observations are usually not. SpaceImplorerExplorerImplorer 19:12, 23 November 2023 (UTC)

AS Cephei has parameters than imply a luminosity of 487,000 L_☉ in Gaia DR3, way above the limit. Diamantinasaurus (talk) 21:32, 28 November 2023 (UTC)

Can this be cited?

This seems to show preliminary results of an interferometric survey of red supergiants. It contains radius estimstes for SW Cep and PZ Cas. Can this be cited or do we need to wait until a paper is published with radii? VY Canis Majoris (talk) 20:19, 28 November 2023 (UTC)

I mthink it can. But with a more accurate distance, PZ Cas would have an absurd radius of 1720 R_☉. Diamantinasaurus (talk) 21:55, 28 November 2023 (UTC)

It can be cited, but I am sceptical of the accuracy though. The parameters (such as with EG And) often rely on low resolution images and yield extremely low effective temperatures, such as 3443 K for the K-type supergiant KK Per and 3278 K for TV Gem. SpaceImplorerExplorerImplorer 14:09, 29 November 2023 (UTC)

Removal of Stephenson 2 DKF 49

Another star whose radius estimate has too much uncertainty is Stephenson 2 DFK 49.

It's estimated to be at least 884 solar radii; https://iopscience.iop.org/article/10.3847/1538-3881/abab15 but as high as 1,300 solar radii with a margin of error of + 258 - 323 solar radii; https://ui.adsabs.harvard.edu/abs/2012ApJ...760...65F/abstract.

The variation in its estimate is too large to make it certain on its spot on the list of largest stars, and the difference between those two radii values would put it at two highly different sections of the list, which can't happen.

Therefore the uncertainty's too high to the point of being unreliable and subject to dispute.

Another star named Stephenson that's been subject to dispute and removal from the list was Stephenson 2 DFK 1, where highly different luminosity values corresponded to highly different radius estimates, making them unreliable as well. Eric Nelson27 (talk) 01:38, 4 December 2023 (UTC)

The 884 R_☉ estimate has an error of over 50%. It's just too unreliable. The larger estimate is well, larger but also more reliable. St2-18 had 90,000 L_☉ luminosity estimate but that did not account for near-infrared, making it an underestimate. Diamantinasaurus (talk) 14:14, 4 December 2023 (UTC)

Refrain from adding stars way larger than the theoretical limit?

I think we should stop adding stars that are much larger than the theoretical limit of star size. (like 1550-1650x larger then the sun) I think this would help reduce the number of inaccurate measurements and overestimations. Atlantlc27Lol (talk) 21:10, 25 November 2023 (UTC)

There aren't any here anyway. Diamantinasaurus (talk) 22:24, 25 November 2023 (UTC)

Im saying exclude them from being added in the future. Atlantlc27Lol (talk) 01:00, 26 November 2023 (UTC)

Some of them should however be kept if they have many dedicated and highly accurate observations. Although Davies et al. (2020) does state that stars above the log(L) 5.5 cut-off would certainly not have been missed so I do not think that any extremely large radii would be constrained for any stars in the near future. SpaceImplorerExplorerImplorer 09:14, 26 November 2023 (UTC)

HD 269551 and WOH S170 both are slighty more luminous than that. I don't think they should be removed though. Diamantinasaurus (talk) 09:22, 26 November 2023 (UTC)

The cut-off of 5.5 only applies to M-type RSGs. SpaceImplorerExplorerImplorer 10:10, 26 November 2023 (UTC)

the temperature of WOH S170 is 3750 K and that of HD 269551 is 3800 K Diamantinasaurus (talk) 10:16, 26 November 2023 (UTC)

WOH S170 would then be M0.5 Ia and HD 269551 would be K5 Ia and the cut-off is quite vague and not an exact value. SpaceImplorerExplorerImplorer 11:00, 26 November 2023 (UTC)

True. The luminosity of WOH S170 is 10^5.58 L_☉ and I don't think that's high enough for it to get removed. Stephenson 2 DFK 1 for example was much more luminous (logL = 5.64). NGC 2403 V14 is in this list and it's luminosity is 3.4 million L_☉ and there are some YHGs with luminosities of up to around 10^5.7 L_☉ but those are YHGs and I suspect that NGC 2403 V14 is probably a LBV during an outburst. Diamantinasaurus (talk) 11:33, 26 November 2023 (UTC)

I made a list of the most luminous RSGs in the Humphreys-Davidson limit section of the Eddington luminosity page. Diamantinasaurus (talk) 20:25, 4 December 2023 (UTC)

Removal of AH Scorpii and KW Sagitarii

Both stars got their estimates from the exact same paper that suggested UY Scuti was 1,708 SR, and if that estimate was unreliable, I think the other two could be unreliable as well. Atlantlc27Lol (talk) 12:17, 5 December 2023 (UTC)

NOTE: Although they could be reliable, because UY Scuti’s estimation was 208 SR above the theoretical limit, and these are a few hundred. Atlantlc27Lol (talk) 12:19, 5 December 2023 (UTC)

• A few hundred below Atlantlc27Lol (talk) 12:19, 5 December 2023 (UTC)

The UY Scuti size estimate was removed because of the old and inaccurate distance. The distance estimates to both AH Scorpii and KW Sagitarii are much more reliable and the latter is in a stellar association. Diamantinasaurus (talk) 15:05, 5 December 2023 (UTC)

The distances for AH Sco and KW Sgr are accurate and masers were used to calculate them rather than the luminosity class. They might be outdated, but are reliable enough for now. SpaceImplorerExplorerImplorer 19:13, 5 December 2023 (UTC)

Absolutely not. UY Scuti is only reliable because the distance they used depends on an assumed absolute magnitude. AH Scorpii and KW Sagittarii have more direct and accurate distance estimates. There is no reason to suspect their method of measuring the angular diameter of the stars is wrong, simply because UY Scuti uses an inaccurate distance. VY Canis Majoris (talk) 11:14, 7 December 2023 (UTC)

Removal of both scale images?

Both of them include old and inaccurate sizes for stars. They are also very old. I suggest deleting them. Atlantlc27Lol (talk) 02:20, 18 December 2023 (UTC)

If we were to remove them, I would suggest maybe using something similar to this one. SpaceImplorerExplorerImplorer 08:56, 18 December 2023 (UTC)

We should use that one. It has accurate size estimates and includes stars with well-known radiuses. Atlantlc27Lol (talk) 11:40, 18 December 2023 (UTC)

Stars that are "possibly" the largest

If you look at the error bars, they are often one to several hundred solar radii. This means that a lot of the values overlap and there are as many as 20 stars that could possibly be the largest. Stellar radii of red supergiants are just not constrained enough to tell what the largest known star is. WOH G64 has a smaller error so is more "likely" to be the largest known, but some stars could still be as larger than this. VY Canis Majoris (talk) 07:05, 20 December 2023 (UTC)

Dark stars

Recently some dark stars candidates were discovered. They're much larger than any red supergiants. Should we include them or not? Diamantinasaurus (talk) 18:27, 4 October 2023 (UTC)

Are there reliable sources that corroborate this information? Primefac (talk) 09:19, 5 October 2023 (UTC)

There is this. They are still candidates though. Diamantinasaurus (talk) 12:14, 5 October 2023 (UTC)

Then we probably should not include them. Primefac (talk) 13:50, 5 October 2023 (UTC)

Yeah. They're still candidates and still could be galaxies instead of dark stars. Diamantinasaurus (talk) 14:05, 5 October 2023 (UTC)

Should we add them into their own sections? Atlantlc27Lol (talk) 21:08, 20 December 2023 (UTC)

UY Scuti’s Extra Sizes

Gaia DR3 claims a radius of 755 solar radii. There was also a radius for UY Scuti which said it was 941 solar radii a few years ago. A radius of 825 solar radii was also given and was on the list for a while, so UY Scuti would probably be ~700-1,000 solar radii. Should we add these back (or atleast one of them)? Atlantlc27Lol (talk) 01:42, 21 December 2023 (UTC)

None of them are really accurate. 755 R_☉ used Gaia DR2 and 2MASS, however the Gaia distance is incredibly noisy. 941 R_☉ also used a noisy Gaia distance and 825 R_☉ used a very specific luminosity logarithm of 5.00 that was also used for other stars. SpaceImplorerExplorerImplorer 10:52, 21 December 2023 (UTC)

825 R_☉ used a luminosity estimate from an older paper which was rounded up too much for some reason and is based on a made up distance of 2 kpc. Diamantinasaurus (talk) 22:56, 21 December 2023 (UTC)

The distance of 2 kpc is similar to the now known distance of 1.8 kpc. Atlantlc27Lol (talk) 13:27, 22 December 2023 (UTC)

The rounding of the value (5.00) is still too imprecise and 2 kpc is assumed and is considered to be very uncertain. Eventhough it is close to the somewhat accurate noiseless distance, it is not really comparable and 1.8 kpc does not change the accuracy of the old one. SpaceImplorerExplorerImplorer 16:54, 22 December 2023 (UTC)

WOH G64’s Radius

This ref (https://ui.adsabs.harvard.edu/abs/2017MNRAS.465..403G/abstract) claims a size of 1540 solar radii (like the 2009 paper about WOH G64), but gives higher luminosities and lower temperatures. This gives a radius of ~1784–2481 solar radii. (Although I’m skeptical about both the temperature, luminosity, and size, and it is probably a little too high as well) Atlantlc27Lol (talk) 02:41, 28 December 2023 (UTC)

To get an accurate luminosity and temperature for WOH G64 you have to carefully model the dust torus. The 2009 paper has done the best attempt of this to date, originating from the previous 2008 paper. Newer papers simply model the torus as spherical, leading to overestimated luminosities and sometimes underestimated temperatures. VY Canis Majoris (talk) 08:41, 29 December 2023 (UTC)

These stars should be added

Milky Way: 1. UY Scuti (1708 solar radii) 2. NML Cygni (1639 solar radii)

Magellanic clouds: 1. HV 2242 (1645 solar radii) (large Magellanic cloud) 2. WOH S71 (1662 solar radii) (large Magellanic cloud) 3. SMC 78282 (1600 solar radii) (small Magellanic cloud)

Messier 31 (Andromeda galaxy) and Triangulum galaxy: 1. LGGS J013339.28+303118.8 (1565 solar radii) (triangulum galaxy) 2. LGGS J003919.11+404319.2 (1685 solar radii) (andromeda galaxy)

Those stars have unreliable estimates, especially the Milky Way ones. Some of them are already on the list with a smaller size anyway.SpaceImplorerExplorerImplorer 07:45, 14 December 2023 (UTC)

UY Scuti uses and old and inaccurate distance estimate.

NML Cygni is a very large star but the 1,639 solar radii estimate is probably inaccurate.

HV 2242 is already in the list.

WOH S71 has a lower luminosity and a higher temperature in Groenwegen et al. (2018). It's still quite big though, at around 900 R_☉ if I remember correctly.

SMC 78282 was in the list, but another estimate gave it a radius below 700 R_☉, making it not even big enough to be in the list.

The Triangulum galaxy star has a luminosity above the Humphreys-Davidson limit but I'm not sure why as the estimate doesn't seem to be inaccurate.

The Andromeda galaxy star size estimate uses a very high extinction, which results in a very high luminosity of 10^5.88 L_☉. Diamantinasaurus (talk) 14:47, 14 December 2023 (UTC)

hv 2242 is not big enough

we should look up again everything about uy scuti before add to the list again

nml cygni should be revised down to 1183 solar radius 2402:9D80:C22:A9B6:A432:A823:AC2C:A651 (talk) 14:51, 31 December 2023 (UTC)

That size is also inaccurate. Atlantlc27Lol (talk) 01:15, 1 January 2024 (UTC)

UY Scuti’s sizes are also inaccurate, and HV 2242 is probably not that large. Atlantlc27Lol (talk) 01:16, 1 January 2024 (UTC)

If NML Cygni is going to be re-added, the luminosity and temperatures equal 1,464 solar radii, so if we re-add it, we should maybe add that size. Atlantlc27Lol (talk) 23:56, 14 December 2023 (UTC)

That would however be WP:SYNTHESIS. SpaceImplorerExplorerImplorer 07:51, 1 January 2024 (UTC)

Removal of some stars

One year ago, I searched the size of VY Canis Majoris. It says 1420 solar radii. But in November 2023 I researched the size and it says 2069 solar radii (the same source on Youtube). That means its size varied too much (649 solar radii)! I also found out that VV Cephei A, BC Cygni, PZ Cassiopeiae and VX Sagittarii also broke the variability rule (all of them varied at least 590 solar radii). Should we remove them??? WOH G64's size is also varied too much (>1000 solar radii). Should we remove it also??? Hoanghao314159 (talk) 14:02, 8 January 2024 (UTC)

2,069 R_☉ uses an outdated temperature and WOH G64’s radius estimation of 1,540 R_☉ is based on a very accurately modelled dust torus. VV Cep A is generally considered to be 1,050 R_☉. BC Cyg’s radius is well known to currently be in the range of 1,000 – 1,200 R_☉ (varies more due to it being a variable star). PZ Cas has a well-defined radius of ~1,100 – 1,400 R_☉ and VX Sgr is well known to be in the range of 1,300 – 1,500 R_☉. Also, YouTube is not a reliable source.SpaceImplorerExplorerImplorer 21:08, 8 January 2024 (UTC)

Grammar of Overview section is very poor.

It's bad enough that I question whether it was written by someone fluent in English.

Taking just the first sentence:

Although red supergiants are often considered the largest normal stars, some other stars were have been found to have temporary temporarily increase significantly in radius significantly during a transient event transient events for a short time (redundant) (in on cosmic scale timescales), such as LBV eruptions or red novae.

The whole section continues in similar fashion. 174.228.226.229 (talk) 06:00, 23 January 2024 (UTC)

No kidding. I've done some rewording which should fix the issue, though I'm happy for further tweaks and input. Primefac (talk) 14:20, 23 January 2024 (UTC)

Cleanup red links (again)

A user cleaned up all red links on this page, but his edits were reverted, claiming that the red links encourages page creation.

But i disagree with this argument, because most of the red-linked stars do not have significant notability to have standalone articles. According to the Wikipedia guidelines on red links, red links are only necessary if their topics have enough notability to become articles. Most of these stars are only listed in very long lists of objects or large-scale astronomical surveys, which do not constitute notability. If an article about one of these stars was created, it would soon be deleted via AfD or PROD because it would not meet any criteria in WP:NASTRO. This has happened previously with articles such as WOH G17 (via AfD), SP 77 46-44 (via PROD), SP 77 31-18 (via AfD), WOH S281 (via AfD), LGGS J004431.71+415629.1 (via PROD) and WOH S281 (via PROD). All were deleted.

So I propose that the red links should be deleted again, as the lack of them indicates that it is not necessary to create an article about the red-linked star.

Note: With the exception of stars in the Milky Way, as perhaps some articles can be created about stars in that galaxy. InTheAstronomy32 (talk) 21:39, 25 January 2024 (UTC)

I do agree that red links should be removed, however I don't agree that we should remove the specific stars from the list altogether, as these are still very large stars that warrant themselves to be on this list. Removing them would defeat the purpose of having a list of largest stars in the first place.

Perhaps we can bypass this by instead having those non-notable large stars having their entries in text form, rather than making a square bracket link that would become red. SkyFlubbler (talk) 17:03, 26 January 2024 (UTC)

I disagree that we should wholesale remove the redlinks from the page. Sure, something with just an IRAS/SMC/HD/etc string of numbers is rather unlikely to ever have an article, but something that is named in a constellation still might have enough interest (being a "named" star) to have an article. In other words, stars outside the Milky Way can probably be delinked, but we should be a bit more circumspect about those within it. Primefac (talk) 12:55, 29 January 2024 (UTC)

Agree. InTheAstronomy32 (talk) 11:59, 30 January 2024 (UTC)

Remove all the stars in galaxies other than Milky Way and the Magellanic clouds?

The stars in galaxies other than Milky Way and the Magellanic clouds should be removed simply because their sizes and other characteristics are very inaccurate (they are too far from Earth to be measured accurately). The star "Godzilla" (in Sunburst galaxy) broke the variability rule (470-2365 solar radii) and its luminosity is too high while its temperature is equivalent to a B6-O9 type star. The largest transient events' sizes are somewhat equivalent to the Quasi star's size (10000-30000 solar radii) and they are very likely to be old and inaccurate radii. The supernova progenitors are mostly too big to be real stars (since we removed UY Scuti). Hoanghao314159 (talk) 13:05, 12 January 2024 (UTC)

There is no clear reason for the stars beyond the Magellanic Clouds to have inaccurate sizes. "Godzilla" has radii that should be correct for specific modelled effective temperatures. It and other stars undergoing or that undergone outbursts, which are transient events, usually increase their size by a huge margin. The sizes on the list for supernova progenitors are mostly accurate and are 'breakout' radii, rather than their usual ones before the supernova. SpaceImplorerExplorerImplorer 18:42, 12 January 2024 (UTC)

Inaccurate radii simply because of larger distances Hoanghao314159 (talk) 09:09, 10 February 2024 (UTC)

Larger distances doesn’t exactly mean that it has to be inaccurate. SpaceImplorerExplorerImplorer 09:15, 10 February 2024 (UTC)

V354 Cephei

The size of 1,520 solar radii for V354 Cephei was removed without reason known to me. Should we re-add it? It would also make it the largest known star in the Milky Way, and the second (or third counting MSX LMC 839 which was also removed without reason known to me), only 20 solar radii behind WOH G64. Atlantlc27Lol (talk) 23:59, 14 December 2023 (UTC)

1,520 R_☉ uses a very high extinction value and is therefore unlikely to be accurate. The star is still on the list but with a lower radius. SpaceImplorerExplorerImplorer 07:46, 15 December 2023 (UTC)

What about MSX LMC 839? Atlantlc27Lol (talk) 11:37, 15 December 2023 (UTC)

It is on here, however, it is named TRM 89 which is another designation for the star. SpaceImplorerExplorerImplorer 13:06, 15 December 2023 (UTC)

The reason for the removal is because V354 Cephei is only 3.6-3.7 solar masses, far less than most red supergiant stars. Hoanghao314159 (talk) 09:17, 10 February 2024 (UTC)

That’s based on Gaia data SpaceImplorerExplorerImplorer 09:25, 10 February 2024 (UTC)

Removal of HV 888

HV 888 was said to be among the largest known stars, but it’s radius estimate varies too much, from 762 to 1,765 solar radii.

This indicates very poor certainty, making its values unreliable.

As a result, it had to be removed from the list.

Stars with smaller variations and better certainty can qualify as members. Eric Nelson27 (talk) 09:18, 3 December 2023 (UTC)

It is still useful to take into account the reliability of each estimate. Massey et al. (2022) got to a very plausible effective temperature of 3650 K and a log(L) of 5.48. The lower and higher values you mentioned have problems with accuracy; the lower value is derived from very low resolution spectra, that even got to a very low distance and the higher value is in a catalogue that contains all sorts of overestimated radii, which is typical if it contains more extreme stars like HV 888. SpaceImplorerExplorerImplorer 11:47, 3 December 2023 (UTC)

Well some stars have been removed by various users due to too much uncertainty in their radii.

NML Cygni, UY Scuti, and Stephenson 2-18 are great examples. Eric Nelson27 (talk) 01:23, 4 December 2023 (UTC)

The difference with them is that they don’t have any reliable radii. SpaceImplorerExplorerImplorer 07:09, 4 December 2023 (UTC)

UY Scuti and Stephenson 2 DFK 1 have no accurate distance estimates (UY Scuti's 2.9 kpc distance estimate is outdated and Gaia parallaxes have very high levels of astrometric noise, the Gaia parallax of RSGC2-01 is literally negative and it's not a member of the cluster in its name). NML Cygni's radius is based on an estimated temperature which is too cold and the star is probably smaller anyway (but it's still very big). The HV 888 smaller estimate is unreliable. If we are counting that, then WOH G64 should be removed too because it's radius estimate range from 1,540 R_☉ to 13,127 R_☉ (which is from the same paper as 1,765 R_☉ HV 888 by the way). Diamantinasaurus (talk) 14:12, 4 December 2023 (UTC)

1800 pc is noiseless unlike the actual Gaia data release parallax. WOH G64's estimate has however been carefully constrained for inaccuracies, making it currently a likely candidate for the largest known star. 13,108 R_☉ is in a large-scale survey that has many overestimations. SpaceImplorerExplorerImplorer 14:35, 4 December 2023 (UTC)

The size estimate of WOH G64 is indeed accurate. HV 888 is also very large and the size estimate is probably accurate. Diamantinasaurus (talk) 15:12, 4 December 2023 (UTC)

I calculated a size of 1,514 Rs for HV 888 but redid it and got 1374 Rs. I used a luminosity of Reid, from 1990 for the first one, and then the values stated. Cosmicwolfanimations (talk) 00:59, 3 March 2024 (UTC)

Technically, you could also say it varies from 762-1974 solar radii, because the 1974 solar radii estimate was on the list for a while (at least it was in 2020 & 2021) Atlantlc27Lol (talk) 03:28, 25 December 2023 (UTC)

1974 solar radii is not a good estimation. SpaceImplorerExplorerImplorer 10:44, 25 December 2023 (UTC)

1,765 probably isn’t either Atlantlc27Lol (talk) 17:34, 27 December 2023 (UTC)

Lower UY Scuti again?

Last time I checked, UY Scuti has a size of 825 SR on here. When was it moved back up to 1708? I heard it was unreliable. Should we lower it back down again? Atlantlc27Lol (talk) 19:16, 7 November 2023 (UTC)

I was thinking of removing it, NML Cyg and some other stars that have effective temperatures substantially lower than the Hayashi line, which could indicate that they are not in hydrostatic equilibrium which would be very unusual if it was permanent. UY Sct has a radius that uses an old distance anyway and a noiseless photogeometric distance based on Gaia EDR3 data, which is also less uncertain and results in a radius of 1,060+118
−98 R_☉ although that would not be added to the list since it fails WP:SYNTHESIS. Wing (2009)'s "Biggest Stars of All" also states that it would be hard to believe that a star like NML Cyg could be stuck in a non-equilibrium state for more than 40 years. Dorn-Wallenstein et al. (2023) states that the Hayashi line is 3650 K, however it also mentions two papers that put the limit at 3450 K for the Large Magellanic Cloud, which is more consistent with stars like WOH G64. Wing (2009) states the Hayashi line to be at around 3550 K, which is also consistent with good observations. SpaceImplorerExplorerImplorer 19:49, 7 November 2023 (UTC)

Well the temperaature of IRC -10414 (3110 - 3300 K) is also below the Hayashi limit and it's a M7 RSG too (NML Cygni is a M6I star). Diamantinasaurus (talk) 20:21, 7 November 2023 (UTC)

NML Cyg’s effective temperature of 3250 K is a direct assumption from its spectral type, where the measured T_eff comes from a source in 1980 that purely uses old interferometry and fluxes for some giant stars. The effective temperature used in the 2012 paper is extremely uncertain anyway and the luminosity leads to a really uncertain radius, and, again, Wing (2009)’s “The Biggest Stars of All” mentions that it would be hard to believe that NML Cyg could remain in non-equilibrium for over 40 years. SpaceImplorerExplorerImplorer 07:21, 8 November 2023 (UTC)

Such a low effective temperature would actually be unlikely or at least very unusual, since the mass-loss rate would be much higher than what is observed. (see Gvaramadze et al. (2014) on page 11) An effective temperature of 3700 K was estimated in Levesque et al. (2005), which is more consistent with the observed mass-loss, however it is inconsistent with its spectral type. SpaceImplorerExplorerImplorer 07:38, 8 November 2023 (UTC)

An important thing to note is that the radius estimate (1,708) is partly circular. The distance comes from a very old source which assumes a distance based on an assumed absolute magnitude based solely on the luminosity class. The newer paper then re-determines a luminosity based on that distance, rather than using the original value. The other stars with angular diameter estimates have estimated distances from much more direct and accurate methods like masers and association membership, so they should be kept, but UY Scuti should likely not be. VY Canis Majoris (talk) 20:32, 7 November 2023 (UTC)

The 1970 paper estimates that the distance to RW Cep is 1.8 kpc, where in reality it is around 3.4 kpc Diamantinasaurus (talk) 20:36, 7 November 2023 (UTC)

no we cant remove uy scuti from being the biggest can you add it? 2601:2C6:580:EEB0:7C30:9C59:994:7CD6 (talk) 23:21, 27 January 2024 (UTC)

Just because you don’t like it being off the list doesn’t mean it should be added back. SpaceImplorerExplorerImplorer 09:50, 28 January 2024 (UTC)

you don't want it being off the list doesn't mean it should be re-added. uy scuti is back on the list recently but with a lower radius based on effective temperature,... Hoanghao314159 (talk) 12:42, 15 April 2024 (UTC)

This should be archived, its back on the list with a better radius. Atlantlc27Lol (talk) 01:36, 2 May 2024 (UTC)