Talk:Hypergiant

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Some of these "hyper-giants" may in fact be very tight clusters of hot, massive stars surrounded by gas. Eta Carinae has been imaged to multiple IR sources.

Yes, that is possible. But you're wrong about Eta Carinae. It is a single (or double) star, that is known. If I remember correctly, Hubble resolved S Doradus into multiple stars in the early 1990s. Still, S Dor is one of the largest stars known, but not impossibly massive as thought earlier (over 1000 MSun).--Jyril 20:20, 18 March 2006 (UTC)

Contents

[edit] Clarification

According to the article,

Hypergiants are the most luminous stars, thousands to millions of times the solar luminosity; however, their temperatures vary widely between 3,500 K and 35,000 K.

This sentence seems to be saying that there's a relationship between luminosity and temperature in hypergiants that isn't what you would expect. E.g., maybe you would think that a hypergiant would be really hot, but some are only 3,500 K. Is that one of the ideas? I don't feel competent to add this clarification. modify 17:16, 24 June 2006 (UTC)

I assume this is referring the the surface tempereature. The surface of the sun is 5,780 K, but it has a much smaller surface area. — Daniel 21:00, 6 July 2006 (UTC)

[edit] Size

This article doesn't give a lower limit for a hypergiant's mass. According to the Supermassive star article, stars with masses greater 60 solar masses are hypothetical (one solar mass is equal to the mass of the sun). — Daniel 21:00, 6 July 2006 (UTC)

The theoretical limit mentioned here at 120 solar masses does not match the one mentioned in the LBV section that puts it in 150. I understand this limit varies slightly according to the composition of the star, but this is too much, isn't it? Which one is correct?. - --Acoyauh (talk) 00:22, 18 January 2008 (UTC)

The Eddington luminosity article declines to give a figure, as should both of the articles in question here. Xihr (talk) 02:40, 18 January 2008 (UTC)

[edit] Picture problem

i dont quiet get the pic actually!!!!


Yeah, what's the point of the picture if the planets and suns aren't to scale? 172.200.211.254 (talk) 22:13, 18 November 2007 (UTC)

The point of the picture is for you to see the scale vs the Sun, in this scale the planets don't even ammount to a single pixel. You should get an idea of the scale this way. -- --Acoyauh (talk) 00:17, 18 January 2008 (UTC) 00:15, 18 January 2008 (UTC)

Why can't we just use both pictures? One to compare a hypergiant to the size of the sun, and the other to compare a hypergiant to our solar system's orbits?

Personally, I think the old picture with the orbit comparison gives a more daunting mental image to the titanic size of a hypergiant star. —Preceding unsigned comment added by 71.239.229.213 (talk) 17:44, 30 April 2008 (UTC)

[edit] B[e] Hypergiants?

B[e] hypergiants turn up in an ADS search for hypergiants. Can anyone specify what they are? --Keflavich 22:33, 1 May 2007 (UTC)

I've added HD 169454, ,Zeta-1 Scorpii, BD+14° 5037, MWC 314, and RW Cephei to the list of hypergiant stars; certainly, they're bright (see [[1]], [[2]], and [[3]]). While two of these articles are quite old, newer ones have confirmed the hypergiant nature of these stars.

[edit] Nuclear Processes?

I would like to know if a hypergiant (or a red dwarf, for that matter) has any substantial difference in nuclear processes vs. the Sun. SystemBuilder (talk) 22:26, 7 March 2008 (UTC)

This talk page is intended for discussion regarding improvement to the article, not general discussion. You might want to google around for general pages on stellar evolution. Xihr (talk) 22:48, 8 March 2008 (UTC)


[edit] Other facts?

Should we add the fact that hypergiant stats would last only a few million years in the main part of their lives, and would be even more imaginable in their giant stage? Supergiants only last around 100 million years in their main part, and the sun as a main sequence star 10 billion? 82.12.88.229 (talk) 22:42, 23 March 2008 (UTC)


[edit] Luminosity class

I am quite new to Wikipedia, so please yell if there is a better place to discuss this on. Xihr, do you have any references for arguing that luminosity class 0 stands for the real hypergiants? According to "The yellow hypergiants" by Cornelis de Jager (1997), all designations (0, Ia0 and Ia+) stands for the same thing, and I haven't found any other articles against that. Actually, Ia+ would probably be the best one, since it is clear that hypergiants are just a small subgroup of the supergiants. Fredrik.Windmark (talk) 21:31, 15 April 2008 (UTC)

This is the right place. No, luminosity class 0 is the hypergiants. Ia is the bright supergiants. Ia+, and Ia-0 are verging classes, where they're in between. This is used throughout the MK system, where X-Y means "something between X and Y," meaning that's it's not quite Y. References are easy to come by; google around for "hypergiant luminosity class 0" (with no quotes) and there are numerous reliable sources that indicate this, including the esteemed Kaler[4]. Think of it this way: If there weren't a difference between Ia+, Ia-0, and 0, then they wouldn't be written differently. Xihr (talk) 06:16, 16 April 2008 (UTC)
Ok, but you can do the exact same thing with Ia0 for example, and get plenty of hits on hypergiants (like David Darlings site [5]). Looking around some on Astro-ph [6] show all three designations for the same thing. The thing with hypergiants is that there is no globally used definition, and quite a lot of different variants are floating around. It is simply not as easy to separate a hypergiant from a supergiant as it is separating a dwarf from a subgiant. And yes, the MKK system would indeed give it 0 if it actually was a distinct group, but many really just want to call it a subgroup of supergiants because of the commonly used Keenan definition, hence Ia0 or Ia+. I think having all three designations in the article would give a more complete view of the subject. Fredrik.Windmark (talk) 07:50, 16 April 2008 (UTC)
The problem with this analysis is that the one quoted citation you used doesn't even include luminosity class 0, but instead stops at Ia-0. X-Y means "X verging on Y," so Ia-0 clearly indicates a luminosity class of "bright supergiant verging on hypergiant." That he didn't mention the clearly implied luminosity class 0 at all isn't dispositive here. Xihr (talk) 20:34, 16 April 2008 (UTC)
The thing is, in this situation, you can't have X verging on Y since we here really don't have an exact definition of Y. Two more articles mentioning hypergiants of various luminosity classes [7] and [8]. The latter is admittedly a bit old, but the point I've been trying to make is that all three definitions are used for the same thing in todays litterature, whether they should be according to MKK or not. I will not take this discussion further, so do what you want. Thanks for the discussion. Fredrik.Windmark (talk) 21:28, 16 April 2008 (UTC)