Star Formation

[charliebigspuds]

Hello,

As I understand it, stars formed after the big bang have since exploded and new stars have formed from the resulting debris. Is there a certain number of times that this can happen or is it finite?

Many thanks in advance.

 

[3488]

Welcome to SDC charliebigspuds,

I will try & come up with an intelligent'ish' answer.

I have put in brackets, comments after statements I have made that I am not 100% sure are correct.

Stars can still form all the time there is hydrogen available. Planets, comets, asteroids, etc can still form all the time there is material available.

It is worth remembering that even aging red giant stars like Arcturus, Aldebaran, Pollux, Epsilon Leporis, etc, are still mostly hydrogen, only that at their cores, hydrogen has largely depleted & they are fusing helium into carbon, atomic oxygen, etc. Some stars like red supergiants Betelgeuse, Antares, etc have gone further & are fusing elements up to iron (think I've got that right, I am not really an astrophysist, rather more into planetary science), but even these stars are still mostly hydrogen.

Hydrogen is still by far the most abundant element in the Universe, followed by Helium, then atomic Oxygen (I think that is correct). Also element heavier than Iron, such as Uranium, Thorium, etc are prodiced in supernovae (I think that is correct) & enrich the intersteeler medium with heavier elements.

In theory given time, hydrogen in the Universe will deplete & star formation will gradually cease,(again I am not 100% sure of this, as I am not a cosmologist).

I have tried, but suspect I am as much use as a parachute on the Moon.

Please silylene, Yevaud, Wayne(s), a_lost_packet, etc, please correct me as necessary.

Andrew Brown.

 

[kg]

Hello,
As I understand it, stars formed after the big bang have since exploded and new stars have formed from the resulting debris. Is there a certain number of times that this can happen or is it finite?
Many thanks in advance.

Not all of the first stars that formed after the big bang have exploded...

http://en.wikipedia.org/wiki/Red_dwarf# ... cteristics
....As red dwarfs are fully convective, helium does not accumulate at the core and, compared to larger stars such as the Sun, they can burn a larger proportion of their hydrogen before leaving the main sequence. As a result, red dwarfs have estimated lifespans longer than the estimated age of the universe, and stars with less than 0.8 solar masses have not had time to leave the main sequence. The lower the mass of a red dwarf, the longer the lifespan. It is believed that the lifespan of these stars exceeds the expected 10 billion year lifespan of the sun by the third or fourth power of the ratio of their masses to the solar mass; thus a red dwarf with 0.1 solar mass may continue burning for 10 trillion years...

 

[neilsox]

So new stars likely won't form from the blow off of even a 50 solar mass star going super nova, unless at least half of the matter came from somewhere else? Rare exceptions are likely, but it appears a super nova in our galaxy now produces zero new stars in the billion years following the super nova more than half of the time, so yes, finite number of times.

When a galaxy depletes it's hydrogen in nebulae to 1% of the total galaxy mass, new stars will rarely be formed, and massive = 50 solar mass stars almost never. In another 100 million years, only one or zero 50 solar mass stars will remain as 50 solar mass stars go super nova less than 100 million years after their birth. Star formation will resume if a galaxy with lots of mass in nebula merges. Please correct if I am thinking wrong. Neil