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#1
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# of star generations needed to produce observed element abundances
Hi,
Just a quick question - I frequently read in popular science level astronomy books that we humans are made of star matter - i.e., that the carbon, oxygen, and other elements beyond helium are made via supernova and so these high Z elements would not be in abundance until some # of supernova had occurred. My question is this - approximately how many "generations" of stars needed to supernova to produce the observed abundances of high Z elements currently observed? Since stars have different lifetimes (and I seem to recall reading that early stars were quite large and had much shorter life times), I understand that the term "generation" is not quite right but didn't know what else to call it? My second question is this - on earth we have a distilled amount of high Z atoms. Is this density consistent with what was available in the proto star that eventually became the sun and the planets? It would seem it must but I was wondering if anyone has observations that confirm this from other star systems. Thanks, Ted |
#2
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# of star generations needed to produce observed element abundances
wrote:
My question is this - approximately how many "generations" of stars needed to supernova to produce the observed abundances of high Z elements currently observed? [[...]] This isn't an answer to your question, but rather a more general comment: There's an article about (indirect) observations of the first stars, as well as a commentary, in the 3.Nov.2005 issue of Nature. Right now I can view it via the url http://www.nature.com/nature/journal...051103-08.html but I don't know whether this works outside an institution with an institutional subscription. I think "fair use" does permit me to quote the following "Editor's summary": The most distant and oldest observable stars are in the metal-rich galaxies seen in images such as the Hubble ultra-deep field. The metal which in cosmology is anything that's not hydrogen or helium must have come from somewhere and as nucleosynthesis happens in stars, there must have been an earlier population of metal-free stars. No existing or planned telescopes can detect them individually, but evidence of their existence has been found hidden in images obtained by the Infrared Array Camera onboard NASA's Spitzer Space Telescope. After removing foreground stars and galaxies from the image, the tiny fluctuations that remain in the cosmic infrared background are the fossil of emissions from the old metal-free stars. Enjoy, -- -- "Jonathan Thornburg (remove -animal to reply)" Max-Planck-Institut fuer Gravitationsphysik (Albert-Einstein-Institut), Golm, Germany, "Old Europe" http://www.aei.mpg.de/~jthorn/home.html "Washing one's hands of the conflict between the powerful and the powerless means to side with the powerful, not to be neutral." -- quote by Freire / poster by Oxfam |
#3
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# of star generations needed to produce observed element abundances
In article ,
wrote: Hi, Just a quick question - I frequently read in popular science level astronomy books that we humans are made of star matter - i.e., that the carbon, oxygen, and other elements beyond helium are made via supernova and so these high Z elements would not be in abundance until some # of supernova had occurred. You need supernovae to get iron and above, but most carbon, oxygen, etc. actually comes from stellar winds from Asymptotic Giant Branch (AGB) stars and planetary nebulae (although you get some from supernovae as well). Still star stuff, and very pretty, even if not as bright as a supernova. http://antwrp.gsfc.nasa.gov/apod/ap050924.html -- David M. Palmer (formerly @clark.net, @ematic.com) |
#5
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# of star generations needed to produce observed element abundances
In message , oriel36
writes wrote: Hi, Just a quick question - I frequently read in popular science level astronomy books that we humans are made of star matter - i.e., that the carbon, oxygen, and other elements beyond helium are made via supernova and so these high Z elements would not be in abundance until some # of supernova had occurred. Due to the observational data emerging from the supernova SN1987A there are indications that stellar evolution needs to be adjusted from present conceptions. I have a copyright from 1990 indicating two external bounday rings with a smaller central ring at the intersection which in turn is parallel with the supernova star.Considering that the rings were observed in 1994,I am rightly proud of my work relating to the process of stellar collapse. What exactly does "hold a copyright" mean? Has this been published anywhere? |
#6
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# of star generations needed to produce observed element abundances
In article , wrote:
My question is this - approximately how many "generations" of stars needed to supernova to produce the observed abundances of high Z elements currently observed? I don't think this question can be answered without making assumptions about (or using a model that addresses) the degree of mixing between (super)nova ejecta and unmodified big bang material. And any realistic model will produce patchiness. -- Aidan Karley, Aberdeen, Scotland, Location: +57d10' , -02d09' (sub-tropical Aberdeen), 0.021233 Written at Tue, 15 Nov 2005 13:57 GMT [MOD: did I get the MIME damage in the signature sorted?] |
#7
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# of star generations needed to produce observed element abundances
I agree.
I'm looking for a back of the envelope kind approximation. For example, if we assume some model for supernova explosions, how many of these explosions (or what rate of supernova explosions) would we need to explain the high Z atom abundances? Then, we can ask the question of whether this # is consistent with the observed distribution of star masses that we could expect to supernova. |
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