APOD: Millions of Stars in Omega Centauri (2024 Mar 28)

Comments and questions about the APOD on the main view screen.
snuggs28
Asternaut
Posts: 7
Joined: Wed Apr 27, 2016 3:23 pm

Re: APOD: Millions of Stars in Omega Centauri (2024 Mar 28)

Post by snuggs28 » Fri Mar 29, 2024 3:33 pm

I'm mostly passive on this board and just like reading the comments. But I do like my Star clusters.

Wait a minute on this remanent core talk. If it is a dwarf galaxy core. It had to be a real old galaxy. The estimated age of the Omega Centauri stars is from 10-12 billion years old. If that is the case, then this Dwarf Galaxy had to be a first or second-generation galaxy.

For the age of these starts, don't they have to be the most stable stars in the known Universe? Am I wrong in thinking this?

User avatar
Ann
4725 Å
Posts: 13543
Joined: Sat May 29, 2010 5:33 am

Re: APOD: Millions of Stars in Omega Centauri (2024 Mar 28)

Post by Ann » Fri Mar 29, 2024 10:21 pm

snuggs28 wrote: Fri Mar 29, 2024 3:33 pm I'm mostly passive on this board and just like reading the comments. But I do like my Star clusters.

Wait a minute on this remanent core talk. If it is a dwarf galaxy core. It had to be a real old galaxy. The estimated age of the Omega Centauri stars is from 10-12 billion years old. If that is the case, then this Dwarf Galaxy had to be a first or second-generation galaxy.

For the age of these starts, don't they have to be the most stable stars in the known Universe? Am I wrong in thinking this?
Very low-mass stars are extremely long-lived. It is possible or even probable that all remaining main sequence stars in Omega Centauri are in fact lower in mass than the Sun. Since the stars of Omega Centauri are also so metal-poor, they are going to be ”bluer for their mass” than a star of solar metallicity. And therefore they will look more massive than they are.

What I’m trying to say is that it is possible that all main sequence stars in Omega Centauri are in fact lower in mass than the Sun. If they had been as metal-rich as the Sun, they would have been orange in color, and we would have known that they were K-type main sequence stars more light-weight than the Sun. If, instead, they had been as massive than the Sun, they would either have turned into red giants by now, or else they would have become little white dwarf burnt-out cinders of their former selves.

Haven't there ever been really massive stars in the globular clusters? Sure there have! But maybe not in Omega Centauri, if it is the core of a dwarf galaxy, since galactic cores are often lacking in massive stars. Then again, it is indeed likely that even the yellow cores of galaxies were once the birthplaces of massive stars. But these ancient heavyweights all died long ago.

So the stars of old globular clusters are not extremely stable, but the remaining main sequence and giant stars are light-weight, and they are all metal-poor. And because they really are so metal-poor, we can be fooled into thinking that they are unusually long-lived for their mass. But they are not.

Ann

I hate that little plural-s on "birthplaces". Of course I missed it, because in my native Swedish we would use the singular form of the noun in that sentence. We would never say, for example, "They scratched their heads" but "They scratched their head". (Or, more precisely, we would say "They scratched themselves in the head".) Missing the plural-s on English nouns because I use the singular form of the corresponding noun in Swedish is one of the million little mistakes I risk making all the time when writing in English. If you only knew how many times I edit my posts!
Color Commentator