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No Mention of the book of Job?[edit]

Forget whether the Bible is "inspired by some God" or not. It is a human artifact, has been exhaustively corroborated for textual authenticity more than any other ancient writ, and it discusses Arcturus. Job 38:31-32:

"Canst thou bind the sweet influences of Pleiades, or loose the bands of Orion? Canst thou bring forth Mazzaroth in his season? or canst thou guide Arcturus with his sons?"

Shouldn't scientific objectivity factor the book of Job, for the information it adds to the discussion, without censoring it out due to theophobia? ~ — Preceding unsigned comment added by (talk) 02:55, 18 February 2012 (UTC)

So the Book of Job mentions Arcturus. Big deal. Why do you think a mere mention is worthy of discussion? — Preceding unsigned comment added by 2600:1000:B02C:ACD:89A6:2F63:3481:D2FB (talk) 06:17, 11 August 2013 (UTC)

To anonymous smart-alec: Why is there a big deal about tropical ancients in canoes then? Be consistent. If ancient references are to be included in some cases, why not others? What do people in canoes have to do with astronomy?77Mike77 (talk) 12:48, 1 April 2014 (UTC)

3rd Brightest?[edit]

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)

Temperature of Arcturus[edit]

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.


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.Cordyceps (talk) 23:36, 25 September 2010 (UTC)

Can Arcturus both be an old disk star and "a remnant of an ancient dwarf satellite galaxy", as stated in the article Arcturus stream? Besides, the Arcturus stream isn't even mentioned in the article. Oz1sej (talk) 09:26, 19 November 2010 (UTC)

I agree. This article might be useful to astronomers, but it has far too much jargon for an encyclopedia article.77Mike77 (talk) 12:52, 1 April 2014 (UTC)

Proper motion[edit]

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)

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).


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)

Stellar Parameters[edit]

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


"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)

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

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 (talk) 17:50, 4 May 2009 (UTC)

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 (talkcontribs) 11:42, 31 March 2010 (UTC)


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)

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


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)

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)

Big Dipper[edit]

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 (talkcontribs) 17:25, 9 June 2008 (UTC)

Start by looking at the "pot" of the Big Dipper. Move out along the arc of the handle and continue along that arc, and you will get to a bright orange star that is Arcturus.77Mike77 (talk) 13:00, 1 April 2014 (UTC)


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

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

I second that - nonsense about Edgar Cayce does not belong in an article about astronomy! I've removed it. Shouldn't the pap from Jose Arguelles also be removed?—Preceding unsigned comment added by (talk) 03:43, 5 April 2011 (UTC)

Culmination is dependent on the observer's position, so how does Arcturus culminate around midnight on April 30th? Correct me if I'm wrong! (talk) 02:56, 31 July 2011 (UTC)


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)

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)

the brightest star in the northern hemisphere?[edit]

given that Sirius is visible in the northern hemspihere this statement seems incorrect (talk) 12:12, 21 December 2011 (UTC)

I was confused about this too. Turns out Sirius actually is in the southern celestial hemisphere. It's relatively close to the equator though so we have plenty opportunity to see it in the north. (talk) 23:44, 9 February 2012 (UTC)

Ambiguous statements[edit]

"With a near-infrared J band magnitude of −2.2,[1] only Betelgeuse (−2.9) and R Doradus (−2.6) are brighter." This can't mean "the third brightest in the Galaxy", so what does it mean?77Mike77 (talk) 12:17, 1 April 2014 (UTC)

Also, "The star culminates at midnight on 27 April, and at 9PM on June 10 being visible during the late northern spring or the southern autumn." As someone without a degree in astronomy (like most Wikipedia readers), I don't know the word "culminate" as astronomy jargon, and the article that the word links to is very poor. According to that article, each star culminates daily, so why this article picks two days of the year is a mystery.77Mike77 (talk) 12:36, 1 April 2014 (UTC)

I haven't read the reference from which this was taken, but I think the idea is to describe to an observer where to find Arcturus in the sky as the year progresses, by giving the dates (A) when it is highest at midnight, and (B) when it is highest at 9PM. That is, the times "midnight" and "9PM" were chosen first, as most significant to a casual observer of the skies, and the dates "27 April" and "June 10" calculated from this. (talk) 23:17, 27 October 2014 (UTC)


To get into article - see here ([1]) Cas Liber (talk · contribs) 13:24, 3 August 2014 (UTC)

Red giant or orange giant?[edit]

The article variously calls Arcturus an orange giant or a red giant. Which is correct? (talk) 22:00, 6 November 2014 (UTC)

Better source for physical parameters[edit]

The physical parameters in the infobox, including mass, luminosity, surface gravity, and temperature, were originally based on the following reference:

Schröder, K.-P.; Cuntz, M. (April 2007). "A critical test of empirical mass loss formulas applied to individual giants and supergiants". Astronomy and Astrophysics 465 (2): 593–601. arXiv:astro-ph/0702172. Bibcode:2007A&A...465..593S. doi:10.1051/0004-6361:20066633. 

This reference was added by user RJHall here. But on examination, it doesn't seem to me like a particularly good source for Arcturus physical parameters. The paper's main subject wasn't Arcturus at all, but testing formulas for calculating the rate of mass loss from giant and supergiant stars. Arcturus was merely used as one of several case studies to be tested. In so doing, the paper does derive some physical parameters for Arcturus, but the discussion of this is brief, and it's not exactly clear how the derivation was made.

I have changed mass, surface gravity, and temperature, as well as radius, metallicity, and age, to use a more recent source which seems to be much better. This was already used to cite the age estimate in the main body, and user Cas Liber also linked to it above (see "Bookmarks"):

I. Ramírez, C. Allende Prieto (December 2011). "Fundamental Parameters and Chemical Composition of Arcturus". The Astrophysical Journal 743 (2): 135. arXiv:1109.4425. Bibcode:2011ApJ...743..135R. doi:10.1088/0004-637X/743/2/135. 

This paper is specifically dedicated to refining the physical parameters of Arcturus by fitting evolutionary models to high-resolution visible and infrared spectral data, as well as using parallax and interferometry data. It has a very thorough discussion and analysis, and several more recent papers concerned with Arcturus cite it.

--Colin Douglas Howell (talk) 07:10, 5 December 2014 (UTC)

Colin Douglas Howell, thanks for doing that - much appreciated. I began buffing this article some time ao with the intention of pushing it to GA or FA status but got sidetracked.....Cas Liber (talk · contribs) 23:17, 8 December 2014 (UTC)