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Old 08-August-2007, 02:56 AM
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RUF RUF is offline
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Default About SN 2006gy

The History Channel show on "The Universe" mentioned the hypernova SN 2006gy in the episode about stars. This SN facinated me: such a big explosion, such a big star!

An astronomer said it was probably a first generation star, because that's the only time stars were made that big. It also has hydrogen lines in it's supernova sperctra. Yet the star is 250 million ly away.

I thought stars that big only lived about 1 myrs, so how could it only be 250 mlys away?
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Old 08-August-2007, 03:07 AM
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Quote:
Originally Posted by RUF View Post
An astronomer said it was probably a first generation star, because that's the only time stars were made that big. Yet the star is 250 million ly away.

I thought stars that big only lived about 1 myrs, so how could it only be 250 mlys away?
I'd question that statement about age. The distance and size are reasonably certain.

Eta Carinae is about the same size. It's only 7500 lightyears away. Is it supposed to be first-generation, too?

===

Edit: was the age comment along the lines of this, from NASA Chandra Feature: NASA's Chandra Sees Brightest Supernova Ever

Quote:
Astronomers think many of the first generation of stars were this massive, and this new supernova may thus provide a rare glimpse of how the first stars died.
Though that might make it sound too old, careful reading might suggest it was only similar to the first-generation stars, not one of them.
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Old 08-August-2007, 05:21 PM
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There are likely spots in the great voids which have very little debris from previous stars. Possibly a very massive star could have been born from a rare mass of hydrogen in a void (very rare) It might be reasonable to call this a first generation star even if it was born 13 billion years after the big bang. More likely the article is not accurate. Neil
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Old 08-August-2007, 05:43 PM
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'First Generation' in this case refers to the star type, not necessarily when the star formed. In any case, 'first generation stars', (I am assuming means Pop III stars) are hypothetical. What should be most eye-opening about this event is the magnitude. Two or three events this bright this close to us should mean that we are looking at a lot of these super bright supernovae events at great distances.

Before events like 206gy, it was reasonable to assume the most distant supernova explosions we observed are like the brightest of the local sample: normal type Ia, even though we have limited spectral information of the most distant events. This assumption is no longer valid, and should be substituted with the assumption that the most distant events we have observe are also ultra-bright! This has major implications for distance scaling, dust extinction and even the physics of supernovae events. This is going to be a fun decade/century of space discovery!
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