Talk:VY Canis Majoris

Mass

There are two different theories of upper mass limit of red supergiants.

One theory says the mass limit is about 40 times solar masses. The other theory says the mass limit is about 25 times solar masses.

If the characteristics in wikipedia pages of the two red supergiants "VY CMa" and "VV Cep" are accurate , the former mass limit is correct. But the simulation tracks of steller evolutions by the current theory accord with the latter mass limit.

I hope the former mass limit(40 times solar massses) is correct.

Kometsuga 16:07, 24 November 2006 (UTC)

Changed size description from hypergiant to a super giant star, despite its size, YV CM is not a hyper giant, it lacks mass of hyper giant star, to qualify for title of hyper giant star must exceed 90 mases of sun, VY CM is less than 40. —Preceding unsigned comment added by 188.220.53.72 (talk) 13:38, 4 August 2009 (UTC)

If this star really is only 25 Solar masses, then it's density (might be wrong, I calculated it myself) would be much less than hydrogen's density. Can't understand how that could be possible, but I guess it must be. I'd like to see it counted on the article, maybe in the infobox.85.217.39.41 (talk) 19:32, 25 March 2010 (UTC)

Size

Regarding the size calculation... assuming a solar radius of 6.96 x10^8 meters, 1800 to 2100 solar radii would be roughly 777 to 908 million miles. Given that Saturns orbit varies between 838 and 939 miles, the edge of the star could be, at times, beyond the orbit of Saturn. Xlation 18:56, 29 November 2006 (UTC)=

If we assume the upper limit, that is. And there are still controversies regarding the size of VY Canis Majoris. It might not even be as big as we think it is. Micasta (talk) 02:00, 8 March 2009 (UTC)

Okay, solar radius = 6.955 x 10⁸ m. 1800 to 2100 solar radii = 1.252 x 10¹² to 1.461 x 10¹². Diameter = 2.504 x 10¹² to 2.921 x 10¹² m. Micasta (talk) 16:16, 18 March 2009 (UTC)

"It would take over 7,000,000,000,000,000 (7 quadrillion) Earths to fill the volume of VY Canis Majoris.[citation needed]" Now why is there the unfamous "citation needed"? Using the wiki links to Solar radius (6.955*10^8m) and Earth (Volume=1.083*10^21m^3) and the volume of the sphere (4R^3*pi/3) everyone can calculate that it'd be about 7.6*10^15 times Earth volume, if the VY CMa were spherical (which it probably isn't, though it probably also doesn't matter much for the magnitude of the ratio). (Of course now someone can say "original research" or whatever that slogan is. But then I'd loose my last faith in secondary school science education). Hoemaco (talk) 19:49, 12 June 2009 (UTC)

Wow

That size comparison w/the sun is absolutely mind-boggling. I have a hard time believing that a star could be that large.C1k3 07:46, 9 February 2007 (UTC)

Agreed- the sheer scale of the Universe and the things in it takes my breath away at times. --Ifitmovesnukeit 19:44, 2 May 2007 (UTC)

And to think this is only the biggest star that WE know of. Holy cow, the biggest one must be HUUUUGE. 66.61.37.37 (talk) 21:50, 5 March 2009 (UTC)

Yo momma so fat, she's bigger than a ja jestem cwelemVY Canis Majoris! -- Zondor 20:49, 9 May 2007 (UTC)

The term "giant monster giga star" can't even begin to describe this. 206.107.103.85 (talk) 21:37, 23 March 2010 (UTC)

oh oh

I just got to think of a thing, if the star Eta Carinae is 7.500 light years away from earth and when it becomes a supernova it might effect earth(i know its not a lethal effect but still ) and if YV Canis Majoris is 5000 light years away then what the hell happens when it goes supernova!? (if it does) :S Kitten!meow 19:11, 31 May 2007 (UTC) Kitten!Meow

Isn't mass the important factor when it comes to supernova effectivity? Well, I'm not a scientist so I wouldn't be sure. 124.106.234.29 (talk) 22:29, 21 March 2008 (UTC)

7,500 light years is a safe distance. A dangerous distance for a supernova would be about a couple hundred light years. Just read that off "Voyages through the Universe" by Fraknoi, et al. Micasta (talk) 10:11, 27 February 2009 (UTC)

Why isn't their a Hipparcos number, or an HD number?? I want to research this star farther on a universe simulation application that I have at home. Can someone put that number on the actual article?? Thanks..65.117.69.179 (talk) 17:47, 3 July 2008 (UTC)

Would it be possible for an event from Canis Majoris, be it supernova, hypernova, steller flare or any other outburst of radiation or energy to cause a chain reaction that would diretly effect smaller stars and therefore their orbiting planets? —Preceding unsigned comment added by ChrisRichards0672 (talk • contribs) 09:50, 22 May 2009 (UTC)

162000 yr calc seems off

That 162,000 yrs calculation is way off. If VY is 2100x the radius of the Sun, which itself is 109x the radius of earth, then the circumference of VY is 2100*109 times the circumference of the Earth. Since 109*2100 is about 229,000, then if it took someone 2.9 years to walk Earth's circumference doing about 24 miles a day, then 2.9 years * 229,000 is about 664,000 years to walk the circumference of VY Canis Majoris. Mark --70.108.162.180 02:25, 17 June 2007 (UTC)

Others authors (Monnier 2004; see page #16 of [[1]] give an even larguer size for that star; the radius of 14 AU given there correspond to a real radius of 3000 times the one of our sun. However, it assumes a low temperature for the star.

I did find the numbers for this star. Please keep them in reference while you edit the page. I just might go ahead and add them if I can.

HIP 35793 HD 58061 SAO 173591

Reference is SIMBAD Thanks so much.. —Preceding unsigned comment added by 71.209.88.139 (talk) 02:28, 4 July 2008 (UTC)

concurrency question

I'm not very well informed on how astronomists usually interpret a sentence such as "This star is likely to undergo a hypernova stage by 3200." in combination with the statements that it is 5k lightyears away, but would that mean that it actually probably underwent a hypernova around -1800 and that we will see this event in about 3200, or that it will undergo a hypernova around 3200 and that we will see this event around 8200?

Could somebody with more knowledge of the subject please clarify this a bit in the article?

I would guess that the correct interpretation is that the hypernova "really" happened ~1800 BCE and that we would observe it in 3200, since the information used by astronomers to make these estimations is ~5000 years old. However, there's always the possibility that these same astronomers already accounted for the travel time and believe that the star has already novaed...

--72.150.43.254 (talk) 04:42, 11 January 2008 (UTC)

I assume , and we all know what happens when you assume something.

Since all things rotate around a something, The Earth rotates around the Sun, the Moon around Earth, what does this giant rotate around. This is scary. — Preceding unsigned comment added by 65.89.12.2 (talk) 11:31, July 2, 2007 (UTC)

Around the center of the galaxy. --142.176.13.19 22:27, 9 August 2007 (UTC)

Yeah, around a cluster of stuff. 64.231.84.236 (talk) 03:49, 11 January 2009 (UTC)

It either rotates around an object with an even stronger gravity field, or not at all (stellae fixae) - 145.103.105.1 (talk) 13:10, 2 February 2009 (UTC)

The term is "revolve," not "rotate." Rotation is the movement of a body on its axis, while revolution is the movement of a body around another body. Anyway, back to the subject... in the case of the Moon revolving around the Earth, for example, it is not only the Moon revolving around the Earth. The Earth is also revolving around the Moon. However, since the Earth is much heavier than the Moon, the center of gravity lies so close to the Earth (imagine trying to balance a huge boy and a little boy on a seesaw; you'll have to place the huge boy nearer the fulcrum of the seesaw), that its revolution around the Moon becomes imperceptible. So what does VY Canis Majoris revolve around? Probably another star that is so small and so dim it is lost in the light of huge VY Canis Majoris, that bully. Or, it could be a lone star, just like our Sun, and peacefully revolves around the center of the Galaxy. Micasta (talk) 10:20, 27 February 2009 (UTC)

Hypernova 3200

Why do scientists think it will hypernova in only 1200 years. Even though this star is in the terminal phase of its existence, it may not hypernova for 100,000 years. Why do they have a date. How can they know this --142.176.13.19 22:27, 9 August 2007 (UTC)

It's an un-referenced addition by an IP editor. I'm removing it. Hatch68 16:45, 9 October 2007 (UTC)

I would kick that star's star ass. —Preceding unsigned comment added by 68.81.122.7 (talk) 04:31, 11 February 2008 (UTC)

Haha yeah, damn pussy star. Vael Victus (talk) 20:08, 25 February 2008 (UTC)

Parent Galaxy

This thing is in our galaxy, right? If so, I suggest adding that fact. Or is it just understood that stars with Wikipedia pages are in the Milky Way unless otherwise noted? Jyoshimi (talk) 22:14, 30 May 2008 (UTC)

Yeah... I don't think we can even observe stars in other galaxies. We can barely see the entire (other) galaxies, let alone the individual stars within them. Yes, this is all in our Milky Way.Nelfer (talk) 14:55, 3 October 2008 (UTC)

You're wrong, Nelfer. Read on the observable universe and galaxy articles. We can observe other galaxies. 64.251.85.182 (talk) 20:09, 14 November 2008 (UTC)

I know we can see other galaxies. I was refering to the fact that we don't have the power to see individual stars and examine them in other galaxies, only within our milky way. If this has changed, then when talking about a star, we should specify in which galaxy is found.Nelfer (talk) 16:36, 29 June 2009 (UTC)

We can see such stars, read WOH G64 for instance, which is the second largest known star currently, but isn't in our Galaxy. However I feel it probably isn't necessary to specify that a star is in the Milky Way, as most known stars are. Certain facts in the article do make it pretty obvious, e.g. the fact that it's only 1.5 kiloparsec away. - filelakeshoe 20:45, 29 June 2009 (UTC)

Maximum star size

Does anyone know why "the largest possible star is approximately 2,600 times the radius of the Sun"? Louis Waweru  Talk  22:45, 4 July 2008 (UTC)

Eddington luminosity.Geni 10:08, 1 September 2008 (UTC)

Saturn in the bath

Article says:

If a human could walk on the surface of Canis Majoris...

Yeah, if the Moon would be a green cheese! Or, if Saturn was put in a huge ocean. Said: Rursus (☻) 21:16, 16 September 2008 (UTC)

I suppose the name Jon Osterman means nothing to you?

-G —Preceding unsigned comment added by 173.32.141.8 (talk) 17:24, 24 March 2009 (UTC)

Original research for walking time?

Uh, is that walking time estimate listed anywhere? Also, is it even necessary to have a walking time estimate given that nobody will ever walk around that star? There are better ways to give a size comparison than a walking time estimate. —Preceding unsigned comment added by 75.43.36.45 (talk) 00:45, 30 September 2008 (UTC)

I had tagged it as WP:SYN but that was removed. If anything it's just a useless comparison that probably should be removed. --George100 (talk) 00:57, 30 September 2008 (UTC)

Some people have trouble with really big numbers. But somehow, if you compare those numbers to money, then they can make a relationship. Like saying if the Earth was $1, then .... they get it. Try it with someone and you'll see.Nelfer (talk) 15:03, 3 October 2008 (UTC)

Photo of VY Canis Majoris

I embedded a photo of VY Canis Majoris taken from HubbleSite. Micasta (talk) 04:25, 3 March 2009 (UTC)

Calculating the absolute magnitude

I used the following formula (see Absolute magnitude) to calculate the absolute magnitude of VY Canis Majoris: $M=m-5((\log _{10}{D_{L}})-1)\!\,$ wherein D_L is in parsecs. Using a distance of 1500 parsecs (which is uncertain, since stellar distances are accurate only up to about 100 light years[2]), and a visual magnitude of 10.19, I calculated an absolute magnitude of -0.69. This value is inconsistent with a luminosity of 2×10⁵ (which is also under dispute... I may contribute more on this in the future). I then used another formula (from Luminosity): $M_{1}-M_{2}=-2.5\log _{10}{\frac {L_{1}}{L_{2}}}$ I used the absolute magnitude of the Sun as benchmark. Let M₂ = 4.83. I calculate an absolute magnitude of -8.4. Which means at least one of the experimental values is inaccurate. Any thoughts on this? Micasta (talk) 01:57, 8 March 2009 (UTC)

SIMBAD says that the parallax of this star is 1.78 ± 3.54 milliarcseconds. Note the relatively large error. Hipparcos has measured the parallaxes of stars only up to 1,600 light years away (see article on Parallax), which is far smaller than the supposed distance of 4,900 light years for VY Canis Majoris. Using the formula: $\sin p={\frac {1AU}{d}}$ (also from Parallax article), and a value of 1.78 mas for the parallax, I calculated a distance of 1830 light years. If I assume a parallax of 1.78 + 3.54 mas, I obtain a distance of 613 light years. For a distance of 4,900 light years, the parallax must be 0.67 mas -- well within the parallax recorded in SIMBAD, but still too inaccurate. Any thought on this? Micasta (talk) 10:15, 8 March 2009 (UTC)

It's little use using the parallax values you cite Micasta since the enormous error makes it invalid. Also your calculations are in error and you forget about correcting for "reddening" i,e, interstellar extinction. A useful recent article on the distance of VY CMa is Reid et al. (2009). Reid, M. J.; et al. (2009). "Trigonometric Parallaxes of Massive Star Forming Regions: VI. Galactic Structure, Fundamental Parameters and Non-Circular Motions". The Astrophysical Journal, in press 700: 137. doi:10.1088/0004-637X/700/1/137. http://arxiv.org/abs/0902.3913.

VY CMa being a maser imbedded in a nebula allowed for much more accurate trignometric parallax determinations using radio astronomical techniques. based on the Reid et al. data distance to VY CMA and the associated nebulosity is 1140 +/- 90 parsecs (3720 +/- 290 light years) equal to a parallax of 0.876 +/- 0.076 mas. Distance modulus is thus 10.28: (log10(1140)*5)-5 = 10.28. Its B-V (colour) is 2.24 which means roughly interstellar extinction (R) of its light is 1.6 magnitudes. This assumes M5-type stars have standard B-V of about ~1.7 (see Wikipedia article on interstellar extinction of light). Assuming maxima apparent magnitude (Av) for VY CMA is 6.6 and mean Av is 8.0 (minimum is 9.6) the estimated absolute magnitude would then be -5.3 and -3.9 (minimum is about -2.3), respectively. The -3.9 value is consistent with the AAVSO spectral type M5Ibpe(C6,3) (see http://www.aavso.org/vsx/), which is based on mean luminosity readings, presumably. Thus at maximum VY CMa is slightly less as luminous as Betelgeuse (Alpha Ori) or Antares (Alpha Sco) but is larger due to being cooler.

--Jb291266 (talk) 04:32, 22 February 2010 (UTC)

RED

Firestorm's change constitutes vandalism. VY Canis Majoris is red, not yellow. Firestorm is not the first to vandalizate this page. the word red has been changed to yellow before, and the change was reverted be me, but the page was re-vandalised by Firestorm. I've reverted his change. —Preceding unsigned comment added by 87.68.100.128 (talk) 18:27, 19 March 2009 (UTC)

size/luminosity controversy

Should the "controversy" about this star's size not be introduced in the lede? The way this article reads at the moment is almost like the second study which claims VY CMa is just a normal red supergiant is seen as a fringe idea or otherwise not generally accepted - for all I know, this may be the case, but it's not clear. The prominence of that contradicting paper should be explained in greater detail, whatever the case. - filelakeshoe 14:07, 31 March 2009 (UTC)

You're right about that. I'm planning to add more regarding Massey's study when I get the time to do so. Micasta (talk) 14:11, 31 March 2009 (UTC)

I just finished reading Massey's paper and it's too technical for my understanding *groans*. An expert on the subject should probably be the one to write on this matter. ^^Micasta (talk) 01:13, 5 April 2009 (UTC)

Yep... I had the same problem, that it was too short and didn't explain the technicalities mentioned, which as an amateur astronomer I hadn't a hope with. Best guess I can make is that it's suggesting that with such a high mass and luminosity, it wouldn't be able to keep itself together at such a low temperature.

There's a bit of an inconsistency in it though, that it states the previously proposed size of VY CMa at 2800 solar radii, and I can't find any report that suggests it's that big. Perhaps if they did their calculations based on that figure then the study will have some flaws. - filelakeshoe 17:46, 14 April 2009 (UTC)

Here's [3] an interesting article from the Sloan Digital Sky Survey that teaches how to calculate the radius of a star. I haven't gotten around to reading it yet (too busy...) but I think it makes use of Stefan-Boltzmann relations. I think this will help us understand what Humphreys and Massey are talking about. I've also found some recent articles (dating 2009) that contest that VY Canis Majoris is not as big as is popularly claimed. Micasta (talk) 04:49, 15 May 2009 (UTC)

Date of Discovery

This article lacks the basic information of its discovery. —Preceding unsigned comment added by 81.106.37.137 (talk) 22:45, 5 July 2009 (UTC)

Density

Some notes on the density would be nice, for example, is it denser than water? Or is it closer to air? —Preceding unsigned comment added by 213.100.13.135 (talk) 23:37, 3 December 2009 (UTC)

Size of VY Canis Majoris in the planetary comparison photo

Should it not be noted possibly in the corresponding caption that the size of VY Canis Majoris in the photo with the many other planetary or solar bodies is based on the lower estimate of 600 solar radii rather than 1800-2100? Although I am not the one to design the photo, it is rather obvious that this is the case. And, to the author of said photo, would it not be more impressive to have VY Canis Majoris increased to its upper size estimation? That is outside my control though, but I still think a clause should be added to the caption of the picture --Suic (talk) 23:14, 14 January 2010 (UTC)

Question

is VY Canis Majoris located in the Milky Way ? Yes or No ? thank you Einkleinestier (talk) 15:18, 10 March 2010 (UTC)

Yes. Grayjack (talk) 20:58, 16 March 2010 (UTC)Grayjack