PDA

View Full Version : Before the Sun?



aflemi01
2007-Sep-17, 08:28 PM
Our Sun is considered a third generation star. What happened to generations 1 and 2? Obviously, some catastrophic event (supernova) must have happened and then all the "stuff" coalesced and we did it again. Here's my question, "What's the possibility that an earlier solar system existed, possibly with life, in those two prior generations? And since the universe is 14 BYO and our sun is about 4.6 BYO, that leaves almost 10 BY for two systems to have existed and then died. That's enough time for life to exist, isn't it?

And what elemental composition percentages make us sure that our sun is a 3rd generation star? Is it the composition of the heavy metals, those heavier than iron?

Thanks.

01101001
2007-Sep-17, 08:54 PM
Here's my question, "What's the possibility that an earlier solar system existed, possibly with life, in those two prior generations?

Not very good for life, I think. The earlier generation stars were more metal-poor, the metals in our sun and its generation coming from the end of prior generations. Plain old mostly hydrogen and helium, the ancestral stars, probably aren't much of a place for life. Their systems might have been less interesting, too, unless you're big into gas giants.

Even 3rd-generation Population I stars and systems are mostly hydrogen and helium, but they contain enough other elements to build more variety.

The previous generations of stars lived their lives. Some 2nd-generation Population II stars are still about. The ancient Population III stars are gone.

Introductory material can be had at NASA Worldbook :: Star (http://www.nasa.gov/worldbook/star_worldbook.html) and :: Sun (http://www.nasa.gov/worldbook/sun_worldbook.html). Also, Wikipedia: Metallicity (http://en.wikipedia.org/wiki/Metallicity) looks good.

And, welcome to the BAUT Forum.

Fraser
2007-Sep-18, 07:24 PM
Him, that's actually a good idea for an episode. We'll cover the various stellar populations.

gaffo
2007-Nov-03, 02:40 AM
its it a thought that the very first stars were nearly totally made of Hydrogen and bigger than even Eta Corina with lifespans of only 100,000 years or so before they blew apart (litterally leaving nothing - not even blackholes).

10,000,000,000 minus 100,000 yrs leaves a very large number and plenty of time for more metal production.

Heard on NPR "stardate" that the above 1st gen. stars and the rare hyper-giants of today like Eta Carina leave no core to collapse - they totally blow apart in full.

I had never heard of that before - I had always thought that bigger = black hole after supernova all these years.

EvilEye
2007-Nov-05, 02:00 AM
Glad you'll cover it, because I just read a paper that says metal rich galaxies don't tend to have new black holes spewing Gamma radiation....


Ww... where did I see that?

parallaxicality
2007-Nov-05, 06:31 PM
I've been working on the Metallicity wiki article for months. I created it by merging five tiny articles together, but I don't have the astronomical knowledge to push it any further. There are some very pertinent questions asked on its discussion page that I simply cannot answer. No one else seems interested in doing anything with it, so if someone on this forum wouldn't mind giving it a go, I'd appreciate it.