Expert: Jayendra Upadhye - 8/26/2009

Question
If a new star can form from the remnants of a former star, how can this be, since the former star ran out of fuel which is why it disintegrated.  So what is it that fuels the new star?

Answer
Hi,
You are getting this slighly wrong.
"New stars form from old stars" does NOT mean that the debris of the old star recollapses and THAT forms a new smaller star!
That is NOT possible, as before its demise, a star may loose 10 to 30% of its mass to stellar winds as a vast and thin planetary nebula. THAT matter is not going to fall in again, because the white dwarf or the neutron star at the center, radiates so much energy that such an eventuality does not arise.

Actually the planetary nebulae are rich in elements higher up in the periodic table because they represent material blasted from significant depths of the star, which was convectively mixed up.
Plus, as the temperature drops in the expanding nebula, the halides combine reactively with the alkalis to form vast clouds of particulate matter such as salts and oxides. Water, gold silver, nickel chromium, Sio2, CaO, Bauxite are all compounds formed "out in space", and during later chemical reactions in clode hot proximity as the hot earth striated after the late bombardment phase of the solar system. But primordial water and salt and SiO2 as old as the solar system is still lurking out there in the Kuiper belt.

We ARE star stuff! The carbon out of which we are made came from distant super Novas near the stellar Nursery that spawned the 3rd generation star we call the sun!

The expanding planetary nebulae seed surrounding space with these higher elements of the periodic table (all the way through urnaium etc), which comes out of the Supernova shock waves propagating into such rich molecular clouds.

Once a cloud of molecular hydrogen (seeded with these impurities from merging planetary nebulae) are compacted by a nearby supernova shock wave, we find a large amount of HOT young stars emerging in a few million years, from light year size chunks of the cloud. M16 is one such stellar nursery. (The Eagle nebula).
If you look carefully, you can see the evaporating gaseous globules (EGGs).
[refer:- http://hubblesite.org/newscenter/archive/releases/1995/44].

Therein lies your answer.
regards
Jayen