Heavy elements from red giants

ImaLooser

I thought all heavy elements came from supernovae, but a recent article by John Baez corrected my ignorance. There is a nice photo too at http://math.ucr.edu/home/baez/diary/index.html#now

twofish-quant

Yup, and you can tell where the element came from by the isotope signal.

s (slow)-process elements come from red giants
r (rapid)-process elements come from supernova (probably)

http://en.wikipedia.org/wiki/S-process
http://en.wikipedia.org/wiki/R-process

And then there are the rare P and rP processes

One reason that much of the heavy elements *don't* come from supernova is that much of the supernova stays with the star. Most of the iron that gets formed by supernova ends up falling back into the neutron star (and we can tell that because supernova produced iron has a special composition that is rich in some iron-isotopes that are relatively rare on earth).

RobinSky

Is there any numbers of how much % of the mass of a star that is iron atoms? I mean for such stars that actually to manage to reach to fuse everything needed to make up iron.

By now I got a bit skeptic on my own knowledge. Do all stars who die from supernova fuse iron? Also did any star who reached fusion of any atom less massive than iron survived (I know they they die anyway) the supernova event?

Best Regards
Robin Andersson

Drakkith

White dwarf stars can accrue mass from a companion and then go supernova. They don't fuse iron, but instead the whole stars burns up in a runaway thermonuclear explosion by fusing carbon. Or were you only asking about massive stars that go supernova on their own?

twofish-quant

A typical supernova has 20 solar masses, and the thing goes boom when the core gets to 1.4 solar mass.

Well... Supernova Ia's happen a different way than type II's. They are C/O white dwarfs that get stuff dumped on to them. Now while the Ia is blowing itself apart it produces lots of iron, but because it happens so fast there's not really time to produce much stuff heavier than iron.

http://www.jinaweb.org/events/fronti...seitenzahl.pdf

Not sure what you are asking here.

RobinSky

Sorry. Let's say we have this star of 4 solar masses, he(the star)is in his last dying year. What I know, not all massive stars, are massive enough to reach the temperatures to fuse atoms to create Iron. So before iron got created in the star, there was probably another heavy element. So, is it possible for stars (except white dwarfs and binaries) to go boom without any iron in its presence?
Hope that was a bit clearer, if not I apologise.

Best Regards
Robin Andersson

twofish-quant

I can't think of any way that a 4 solar mass star can go boom without a binary companion. My tenative answer to that question would be no, although someone might correct me with some astrophysical process that I haven't thought of.

RobinSky

Then if true, maybe the answer is no - all stars who go boom on their own had the presence of iron in its mass. (This is another way to ask my question - but more as a statement).


I think I have to become better at explaining!