Talk:Arcturus

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3rd Brightest?

Is it worth pointing out that Arcturus appears to the naked eye as only the 4th brightest star in the night sky, rather than the 3rd (as mentioned in the article)?

Alpha Centauri A and B are too close to each other for the naked eye to resolve them as separate stars, even when they are furthest from each other in their orbits, and the human eye percieves them as a single star, with an apparent magnitude of around -0.27, 0.23 magnitudes brighter than Arcturus (nearly 25% brighter). Richard B 14:35, 12 October 2005 (UTC)

Right, I've edited it in. Richard B 02:37, 21 November 2005 (UTC)[reply]

Temperature of Arcturus

Changed the temperature on the box on the right to 4,300K based on a recent scientific paper.

This also fits with the other data such as radius and total-power output reported in the article.

System

This is interesting, but as written 'Arcturus is thought to be an old disk star, and appears to be moving with a group of 52 other such stars.' it doesn't tell the reader what an old disk star is. I would like to link the term disk star to something useful, but I don't know what is meant and so refrain from doing this myself.

Proper motion

It is now at its closest point to the Sun…

That doesn't agree with a radial velocity of −5.3 km/s. Based on numbers from the Starbox, I calculate closest approach in about 4000 years (assuming zero acceleration). That may qualify as now on the timescale of stellar motion, but some readers may not derive their sense of nowishness from astronomy. Those who don't plan to stick around until then, for example.

…and is moving rapidly relative to the solar system.

At a true velocity of 122 km/s, actually, so I added that to the article.
—Herbee 16:42, 17 May 2006 (UTC)[reply]

A Leroy Tobey published in Smith's Magazine July 1906 a theory that our solar system is describing a circuit around Arcturus with a 104,000 year period. This is the only reference I am aware of concerning this theory. I think this article is discussing the evidence used for this theory in this section, but I am not knowledgeable enough to know. It may be worth mentioning/discussing (true or false).

Hunter?

I removed Hunter from the description of Boötes because in my experience I've never heard it called the hunter. I have heard Herdsman and Bear Watcher, but never Hunter. If someone can come up with some evidence, then sure, but even then it may make more sense in the article about Boötes. Phil 15:06, 12 April 2007 (UTC)[reply]

Stellar Parameters

This section combined three discussions of stellar parameters which I feel are strongly related. --Neo (talk) 12:56, 28 January 2008 (UTC)[reply]

Mass

"Its mass is hard to exactly determine, but may be about 3.5 times that of the Sun."

Are there any sources for that statment? I have read (googled) that even 3,4 times the mass of the sun is possible. --FrancescoA (talk) 09:11, 24 January 2008 (UTC)[reply]

http://www.stellar-database.com/Scripts/search_star.exe?Name=Arcturus

Says 3.5 masses. Benkenobi18 (talk) 06:08, 2 January 2009 (UTC)[reply]

The mass of 1.5 solar masses (as written in the text) now really doesn't fit to the starbox data (3.5 solar masses). At least one mass should be changed... —Preceding unsigned comment added by 85.177.126.226 (talk) 17:50, 4 May 2009 (UTC)[reply]

That stellar-database web site isn't exactly a scientific reference. The value of 3.4 solar masses is from a paper by Hatzes & Cochran 1993 so if anything that paper should be cited, not some random web page . But mass and age should actually be removed from the list as neither is known. —Preceding unsigned comment added by Turritus (talk • contribs) 11:42, 31 March 2010 (UTC)[reply]

Radius

I've changed the radius to 26 solar. This is based on the calculation sqrt(L/(4*pi*sigma*T^4)) = R. L is derived from the relationship L = Lsun*10^((Msun-Marcturus)/2.5) and T = 4300 K (which is consistent with the B-V value of 1.23 taken from Simbad).

The picture is also off by a factor of 2. Arcturus should be twice as large as shown (or the Sun should be half as big...) Gonzo22 (talk) 08:45, 28 January 2008 (UTC)[reply]

The second picture showing the relative sizes (in the "Ancient Greece" section) is more accurate and should be used instead of the first picture.Gonzo22 (talk) 07:51, 1 February 2008 (UTC)[reply]

According to the paper 'Angular diameters of stars from the Mark III optical interferometer' [Astron. J., 126, 2502-2520 (2003)], Arcturus has a limb darkened diameter of 21.373 ± 0.247 mas (milli-arcseconds). At the Hipparcos (unrevised) distance of 88.85 mas this means that the diameter is 25.87 ± 0.30 solar radii (actually the errors will be a little greater as I've ignored errors on the distance).

Therefore your estimate is supported by an independent measure, and I support the edit. I shall edit the page to reflect the above reference presently. --Neo (talk) 12:56, 28 January 2008 (UTC)[reply]

Thank you. I have added your info to the german Wiki. --FrancescoA (talk) 13:27, 28 January 2008 (UTC)[reply]

Luminosity

I have changed the Luminosity to 210 solar which is from the equation stated above, L = Lsun*10^((Msun-Marcturus)/2.5). Note: Absolute bolometric magnitudes were used (Mbolsun=4.74, Mbolarcturus=-1.069). The result (8.09*10^35 ergs/s) is divided by Lsun (3.839*10^33 ergs/s) to give ~210 Lsun.

I noticed the subscript symbol for Sun is displaying as an empty box, I'm not sure yet how to fix it.

btw sorry for the unformatted equations, I haven't learned Latex syntax yet...

Gonzo22 (talk) 09:03, 28 January 2008 (UTC)[reply]

Using the values of 25.87 solar radii and 4300 K, I get the luminosity as being 205 ± 5 solar luminosities, which is good as it is largely consistent. Does anyone know the proper way to reference a conclusion based upon mathematical / physical equations? --Neo (talk) 12:56, 28 January 2008 (UTC)[reply]

Big Dipper

I was unable to figure out how to use the handle of the big dipper to locate this star. Is there better instruction on this somewhere? I looked up the Big Dipper, but no help there either. —Preceding unsigned comment added by Jokem (talk • contribs) 17:25, 9 June 2008 (UTC)[reply]

Comment

The section on Edward Cayce doesn't make sense to me. EplusE (talk) 05:28, 28 October 2008 (UTC)[reply]
(moved to correct place in sequence. Moonraker12 (talk) 15:28, 8 April 2009 (UTC))[reply]

How about removing the Edgar Cayce reference entirely? This kind of nonsense really has no place in this article. —Preceding unsigned comment added by 68.196.122.36 (talk) 02:52, 9 June 2010 (UTC)[reply]

Seismology

The section on oscillations in Arcturus is very outdated. See recent papers by Retter et al and Tarrant et al, for example. Does anyone have time to update this section? Timb66 (talk) 13:31, 29 March 2009 (UTC)[reply]

Fascinating area but I have absolutely no clue as far as star articles go. What should it say? Casliber (talk · contribs) 19:51, 29 March 2009 (UTC)[reply]