Unravelling the History of Stars: 14 Billion Years

[thenewmans]

I have a series of questions here all around me attempting to get a better image of what has happened around here over the last 14 billion years. You don’t have to answer them individually. One good explanation might answer them all.

Q1: About how many novas, supernovas and such have the matter in our bodies or in Earth gone through? I assume there’s an estimate based on the proportion of elements or something like that.

Q2: How big were the stars from which we are made? I assume we use to be in some pretty big stars since we have iron. Maybe the first one was really big.

Q3: Did our iron come from one nova and our oxygen come from another? Maybe our stellar nursery was made from several novae.

Q4: Can we tell if any stars near us were made from the same stellar nursery as ours?

Q5: When did the novas occur? If our solar system formed 5 billion years ago, maybe the nova was 6 billion years ago. Maybe there was a flurry of supernovas when the universe was young.

 

[Chronos]

1. It is difficult to discern what materials originated in nova v supernova. It is probably safe to say the majoritiy of heavy elements in the solar system originated in supernava. If we had a precise accounting of the relative amount of heavy elements in the solar system, we could calculate the relative contribution of star 'guts' to the mass of the solar system. There is no reliable way to estimate the number of stars that contributed to the initial gas / dust cloud from which the solar system originated.

2. The lower mass limit for a supernova progenitor star is thought to be about 8 solar masses. Most of the contributors were probably from much more massive stars. Population ! stars, comprised of primordial gas, may have exceeded 100 solar masses.

3. It was almost certainly a mix from a number, possibly large number of deceased stars.

4. Stellar spectroscopy shows a large number of stars of similar chemistry as the sun in this part of the galaxy. They were not, however, always neighbors. Stars flow in and out of galactic regions over billions of years. Perhaps none of our current neighbors were formed in the same nursery as the sun.

5. Supernova are believed to have been much more common in the early days of our galaxy. We see evidence of this in distant young galaxies in the universe. The spectra of galaxies gives us an indication of their ages.

 

[thenewmans]

I see. OK. I kept imagining a large star exploding and then recondensing into a stellar nursery. But I see now that novas and stellar nurseries are very different things.

Thank you for your thorough answer.