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How many generations

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16 years 2 months ago #66931 by Rice
How many generations was created by Rice
Here is a question that has puzzled me for a while.

We know the Earth is approx 6b years old and the Universe 15-16b years.
(Feel free to correct my figures I am too lazy to look them up!).

We know the elements that occur naturally on it and we also have theories suggesting the conditions that manufacture them from primorial (in a stellar sense) Hydrogen- eg Iron from nuclear fusion of a mainstream star. Heavier elements require Novae etc.

Can anyone hazzard a guess based on standard theory of stellar evolution on how many generations of stellar lives have gone into providing our current home?

ULT

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16 years 2 months ago #66936 by ftodonoghue
Replied by ftodonoghue on topic Re: How many generations
I think I remember hearing that our sun is a third / fourth generation star, but couldn't be sure

Cheers
Trevor

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16 years 2 months ago #66939 by jeyjey
Replied by jeyjey on topic Re: How many generations
I'm also under the impression that it's a fairly low number (certainly in terms of cosmology) -- but I don't have a specific figure.

-- Jeff.

Nikon 18x70s / UA Millennium                              Colorado:
Solarscope SF70 / TV Pronto / AP400QMD             Coronado SolarMax40 DS / Bogen 055+3130
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16 years 2 months ago #66940 by Seanie_Morris
Replied by Seanie_Morris on topic Re: How many generations
Our Sun is definitely a second generation. As to it being any more is up for speculation based on the apparent known age of the Cosmos (13.7 billion years old). We know it is a second generation because of the make up of the other bodies around it. We have abundant elements such as heavy metals like iron, aluminium, titanium, and more in the planets and asteroids. These elements, in fact almost the periodic table above iron in weight (8 is it?) can really only be produced out of an atomic explosion like that of a supernova. So, the theory goes that the predecessor in our part of the galaxy became a supergiant, exploded when its fuel was exhausted (producing those heavy elements in the process), and from the nebula left over, our Sun formed. The rest, as they say, is history.

Seanie.

Midlands Astronomy Club.
Radio Presenter (Midlands 103), Space Enthusiast, Astronomy Outreach Co-ordinator.
Former IFAS Chairperson and Secretary.

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16 years 2 months ago #66942 by Petermark
Replied by Petermark on topic Re: How many generations
Parts of the presolar material have been preserved.
Their isotopic make up is very different from the solar value indicating that they were born in a range of presolar stars.
See:
en.wikipedia.org/wiki/Presolar_grains

As for how many "generations".
As Jeff said it's a very low number but it would depend on the masses of the precursor stars.
A lot of generations of supergiants have exploded.
On the other hand the first generation of brown dwarfs is still here and will be for tens of billions of years into the future.

Mark.
Anybody who says that Earthshine is reflected Sunshine is talking Moonshine.

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16 years 2 months ago #66979 by Rice
Replied by Rice on topic Thanks
Thanks to all who replied, especially Seanie and Petermark.

The reference you supplied to the Wiki entry on Pre Solar Grains was very interesting and lead me to the Nucleosynthesis entry which in summary goes something like:

300seconds after the Big Bang elements up to At No 3- Lithium form.

Stellar Fusion elements to At No 20 Calcium and At No 26 Iron

Supernovae and Fast Fusion Nickel At No 28.

Yes the suggestion that we may be on at least a second generation planet seems reasonable.

ULT

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