Talk:Betelgeuse

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1 Diameter
2 Roarer/Announcer
3 Diameter/Radius
4 Names
5 Age
6 Metric vs. Imperial
7 Pronounciation?
8 Effect of supernova neutrinos
9 Exaggerated variation?
10 Astrology out of these articles!
11 Stadium
12 Betelgeuse diameter
13 Angular diameter
14 Multiple star system
15 Spelling
16 Possibility of AGB star

[edit] Diameter

What is the actual diameter of Betelgeuse ? In the article 1e12 metres I see: 1200 million km; but the Betelgeuse article mentions this:

290 million km -- 1.9 AU -- Minimum diameter of Betelgeuse

480 million km -- 3.2 AU -- Maximum diameter of Betelgeuse

and these numbers are also copied in 1e11 metres. In [1] the NASA makes a claim that is compatible with the first measure, not the last ones: If placed at the center of our Solar System, it would extend past the orbit of Jupiter. I'm not an astronomer, so I can't tell which is true. -- FvdP 12:34 Sep 4, 2002 (PDT)

The discussion continues in Talk:1e12 metres -- FvdP

Note that there are many different radii for supergiant stars like Betelgeuse. For example the disk of Betelgeuse looks about twice as large in the UV as in the infrared, whereas the gas density radius is completely different to both of these. Rnt20 3 July 2005 20:28 (UTC)

Bizzarely the diameter measurements quoted in the article (290 million km -- 480 million km) disagree completely with all the sources given and all the discussion on this talk page. If the Sun's diameter $D_{\bigodot}$ is 1.4 million km, then $650\times D_{\bigodot}$ is 900 million km. Similarly if you take the measured diameters (0.049 to 0.060 arcseconds) and the distance (427 ly) you get diameters around 900 million km. I'm going to change the article as this seems ridiculous. Rnt20 15:15, 8 March 2006 (UTC)

What is the source of the mass and diameter data? AxelBoldt 20:50 Sep 29, 2002 (UTC)

In response to the conflict in which orbit it would reach in our solar system: I've read that when the sun enters its red giant stage, it will consume the inner planets. I Beetlegeus is a supergiant, then it seems more likely to me that it would pass jupiter were it in our solar system. However, remember that in the article it says that it would pass the orbit of Mars, not making any claims as to where it would actually reach.

--213.118.81.5 23:21, 23 Aug 2004 (UTC) I am confused about the statement of brightness in the article. It states it is the 13th brightest star in the sky. If one follows the link to the list of brightest stars, it seems that Aldebaran is actually the 13th (as mentioned in the aldebaran article) and Betelgeuse is 10th... so which is it ?

[edit] Roarer/Announcer

I'm removing the reference to Betelgeuse being the first star of Orion to rise, since this is probably not correct. Bellatrix rises before Betelgeuse, and on much of the globe (probably for the ancient greeks and arabs too) Rigel also rises before Betlegeuse.

Furthermore, there's a nearby star (in the constellation Canis Major) that is know as Roarer (Murzim), so I'm removing this as well.

I've searched the web for combined references to Betelgeuse/Roarer and Betelgeuse/Announcer, and most if not all of the sites returned are mirrored Wikipedia articles. Others mention that the title of Roarer/Announcer has also been applied to Bellatrix, which would certainly be more correct.

[edit] Diameter/Radius

There is a (large) difference between the values of the radius in the table and the diameter. Which one is the right one? Gunnar Larsson 23:10, 12 Feb 2005 (UTC)

Britannica concise encyclopedia 2005, Serbian edition states that Betelgeuse is 500 times larger than the Sun in radius, and the brightest star of the Orion constellation. In our article is stated that Betelgeuse is 650 times larger then the Sun in radius, and that is SECOND brightest star of the Orion? OK, we have already discussed about radius, but what is actually truth when it comes to brightness, (that should be fairly easy to determine)? -- Obradović Goran (ta^lk 19:34, 10 Jun 2005 (UTC)

Encyclopædia Britannica says (rightly) that Rigel is the brightest star in Orion. On the other hand, Betelgeuse is a variable star. At its brightest, it is almost as bright as Rigel. It may have been sometimes even brighter than Rigel. That may be the reason why it's the alpha star and not Rigel. But that cannot be confirmed. And Bayer atlas is full of such irregularities anyway.--Jyril 21:29, Jun 10, 2005 (UTC)

Actually, Bayer's catalogue doesn't necessarily classify the brightest star of each constellation as "alpha" to begin with. In this case, it was probably one of those rare occasions when Betelgeuse was even with Rigel, which does happen on rare occasions. However, it's safe to say that Betelgeuse is the most noteworthy star in Orion, even if Rigel is a little brighter, and might have been "alpha" for that reason alone. (Ex: We never made a movie called Rigel, did we?) Bayer did this in Draco. Thuban isn't anywhere near the brightest star in Draco, but it's still Alpha Draconis because of its historical significance of being the north pole star in ancient Egypt. John

[edit] Names

I have cleaned the section on the origin of the name to a certain extent to make it more readable as an encyclopedic article and I have also removed some alternate names that were basically just different spellings of Betelgeuse.--Kalsermar 20:03, 28 November 2005 (UTC)

How is the name pronounced please ? (not English beetle juice)

[edit] Age

Is it really only 6 000 000 years old as the infobox says? I thought stars were much older than that! I had a look at other red giants' infoboxes but they were unknown. Or is this just an estimation of how long the red giant phase of it is? Or am I an idiot who's forgotten how to read standard form? --86.130.152.12 00:44, 5 December 2005 (UTC)

The more massive the star is, the faster it uses its hydrogen supply. A star less than 30 M_Sun spends 10¹⁰/Mass³ years in the main sequence. For Betelgeuse, the time is somewhere between 2 and 6 million years (if the star's mass is between 12 and 17 M_Sun). In addition, the star spends maybe a couple of million of years as a post-main sequence star. Anyway, I'd like to see the source of that value.--Jyril 12:07, 5 December 2005 (UTC)

[edit] Metric vs. Imperial

While I support the metric first edit on the physical properties of the star I think it is inappropriate in the case of the 100 inch Mount Wilson telescope. No one, especially in the scientific community, will ever talk about the 250cm telescope at Mt. Wilson. It is a historical name which should be kept. I have seen a discussion, but I'm not certain where it was on Wikipedia, about this very topic and it was determined that in the case of historical designations for telescopes inches would be used. In this case at best, put metric in brackets after the imperial designation.--Kalsermar 20:33, 11 December 2005 (UTC)

[edit] Pronounciation?

can anyone add the right english pronounciation for the name of this star?

How do you pronounce "Betelgeuse"?--Pokipsy76 11:31, 22 April 2006 (UTC)

Depends. Most English speakers go for "beetle-juice", but German or other Europeans might say "Bay-tel-goy-ze". Graham 15:08, 22 April 2006 (UTC)

It's pronounced like "Beetlejuice." Really.

[edit] Effect of supernova neutrinos

I just removed this paragraph from the article:

There is a newer, alternative theory that due to a massive emission of neutrino particles in said supernova event, life on Earth could be drastically altered if not exterminated.

This is a pretty major statement that deserves at least a citation, and probably a rewrite of the preceeding paragraph that claims there's a consensus that the supernova would be harmless. Tossed in casually as it was, I think this paragraph only detracted from the article. --P3d0 13:16, 6 March 2006 (UTC)

Supernovas create incredible amounts of neutrinos. Although neutrinos interact extremely weakly with matter, there are so many of them close to a supernova that neutrino bombardment may be lethal. But definitely not at the distance of Betelgeuse.--Jyril 18:19, 6 March 2006 (UTC)

[edit] Exaggerated variation?

In the article it suggests that the diameter of Betelgeuse varies by (almost) a factor of two with time. All the papers I have seen which give accurate diameters for Betelgeuse quote numbers in the range 0.049 arcseconds to 0.060 arcseconds for the uniform disk diameter in red light -- i.e. varying by about 20 % (there are very much larger values in the UV, where you are just measuring the size of the corona rather than the star itself, and different for "limb-darkened diameters", which is a quite different type of measurement). Now there are a couple of "wild" diameter measurements but these were done using very innacurate techniques, so I don't think they show evidence for big variability in the diameter. Does anyone know where the factor of two variation quoted in the Wikipedia article comes from?

Rnt20 14:46, 8 March 2006 (UTC)

I don't know the source of that info but a factor of two for the diameter does sound a bit much.--Kalsermar 16:08, 8 March 2006 (UTC)

I have now replaced the diameter figures in the article, as discussed at Talk:Betelgeuse#Diameter. Rnt20 16:17, 8 March 2006 (UTC)

[edit] Astrology out of these articles!

Please, put astrology somewhere out of the astronomy articles! Or should I put a sci-fi novel about Betelgeuse in the article? There is science and there are borders to it, all the rest, whether astrology or science fiction, is human invention.

I agree that astrological information should be kept to a bare minimum in astronomical articles and I have been trying to edit some of that stuff out of certain articles as I come across them. A short mention of astrological importance with appropriate internal link is different of course.--Kalsermar 13:41, 15 April 2006 (UTC)

I see no problem with putting astrology in a clearly labelled section. Science fiction would also be fine assuming it is sufficiently notable. --P3d0 14:48, 15 April 2006 (UTC)

Astrology, although being nonsense, has considerable cultural and historical value. Anything that can be considered as "notable" should be included in these articles (for example, Algol being the Demon Star). However, it is important that astrology shouldn't be mixed with the facts in the articles.--Jyril 14:57, 15 April 2006 (UTC)

[edit] Stadium

Texas Stadium was chosen because it's about the right size. Is there some reason we should want to be less specific? --P3d0 20:46, 1 June 2006 (UTC)

[edit] Betelgeuse diameter

It is not logic that Betelgeuse shows a diameter of "only" 650 times the Sun according its characteristics.

Based on its parameters I.C. =1.86; Mabs = -5.14 we get, Rs = 10^ (0.82*IC - 0.2*M + 0.5) = 1130 times the Sun. For I.C.=1.77 as listed, we get R = 954 Rs, 30% larger that the one listed ! In practice there are consensus to consider that the surface of Betelgeuse is over 1000 times of the sun, thus reaching 1.5 billions km, equivalent to the distance to Saturn... Please correct the table consequently.

PS. Parameters of giants stars are difficult to get as the Mass-Luminosity relation does no more apply. But spectroscopic parallax allow us to get quite accurate figures -Luxorion.

NB for large stars like betelgeuse, I think astronomers normally simply measure the diameters rather than estimating them theoretically. Examples of recent measurements of Betelgeuse include:

I assume that the sizes quoted on Wikipedia would be the measured sizes, and not some kind of theoretical estimate. If the Sun's diameter $D_{\bigodot}$ is 1.4 million km, then $650\times D_{\bigodot}$ is 900 million km. Similarly if you take the measured angular diameters (0.049 to 0.060 arcseconds) and the distance (427 ly) you get diameters around 900 million km, so it seems reasonable. Rnt20 13:06, 8 September 2006 (UTC)

Section 6 of the IOTA reference gives a derived $R_{\alpha Ori} = 620 \pm 124 R_{\bigodot}$ . (The linear-model radii was 645 ± 129.) That looks like the most recent estimate, so it's probably the best available. — RJH (talk) 19:02, 8 March 2007 (UTC)

[edit] Angular diameter

You should add angular diameters of the star in milliarcseconds to every star articles that has starbox with the astrometry subbox. Copyright:18 December, 2006 at 01:50 UT

Angular diameters are only available for nearby, giant stars. The majority of stars with astrometric data won't have this available. So I think it's sufficient to cover a measured angular diameter in the text. — RJH (talk)

[edit] Multiple star system

I see references on the web (such as[2] & [3]) that Betelgeuse is a multiple star system (between 4 & 6 stars in total depending who you read). Surely this should be mentioned ? Even if the article focuses on the main 'big' star, some details on the companions (if they exist), their sizes, classes, distance, etc, should be added ? The Yeti 13:59, 28 January 2007 (UTC)

[edit] Spelling

"also written Betelguese and Betelgeux" suggests that these are acceptable variant spellings of the name. They're not. This would be like saying "mischievous (also written mischevious"). We shouldn't be supporting inaccurate spellings. Redirects have their place, but that should be as far as it goes. I've removed the offending words. JackofOz 00:50, 9 February 2007 (UTC)

[edit] Possibility of AGB star

Betelgeuse might be an AGB star. If so , Betelgeuse is not a true supergiant and the mass is below 8 solar masses.

In contrast , Antares should be ( or must be ) a true supergiant because the estimated mass is 15.5 solar masses and the estimation is relatively precise. Antares is a binary star. The mass is calculated from orbital motion of the binary.

The luminosity of low mass (but true) red supergiants with 8-15 solar masses and most luminous AGB stars is almost equal. But comparing the peak of luminosity, the luminosity of true low mass red supergiants is slightly greater.

Reference URL: Magnetic activity in late-type giant stars: Numerical MHD simulations of non-linear dynamo action in Betelgeuse

Evolution of low and Intermediate mass stars

Kometsuga 11:04, 14 March 2007 (UTC)

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