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# of star generations needed to produce observed element abundances



 
 
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  #1  
Old November 14th 05, 03:09 PM
external usenet poster
 
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Default # 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  
Old November 14th 05, 06:15 PM
Jonathan Thornburg -- remove -animal to reply
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Default # 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  
Old November 15th 05, 09:37 AM
David M. Palmer
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Posts: n/a
Default # 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)
  #4  
Old November 15th 05, 11:22 AM
oriel36
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Posts: n/a
Default # of star generations needed to produce observed element abundances

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.

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


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.

http://th.nao.ac.jp/openhouse/1998/v...e4/sn1987a.jpg

The abundance of different types of elements on this planet may be
due to the stellar evolution of our parent star with remnants of the
original stellar evolution event still in our neighborhood.Rather than
stellar birth to stellar death,there may be other stages involved that
so far have yet to emerge.As my speciality is not stellar processes but
rather the geometric modelling of celestial structures by using cycles
and the lessons learned from heliocentricity,perhaps an enterprising
participant will look further into the conception.

[Mod. note: they might like to begin by asking how far the Sun has
moved since it was formed -- mjh]
  #5  
Old November 15th 05, 01:02 PM
Jonathan Silverlight
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Posts: n/a
Default # 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  
Old November 16th 05, 09:31 AM
Aidan Karley
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Posts: n/a
Default # 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  
Old November 16th 05, 03:04 PM
external usenet poster
 
Posts: n/a
Default # 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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