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GRB 090423
Posted: Fri Nov 09, 2012 11:22 am
by saturno2
GRB 090423 is a object super distant, wich exploded just
630 million years after Big Bang.
The age of Universe 13,700 million of years
Distance of GRB 090423
13,700 - 630 = 13,300 million of light years
Not could to be a supernova, because the stars were in
formation.
What were this object?
Re: GRB 090423
Posted: Fri Nov 09, 2012 2:24 pm
by bystander
Re: GRB 090423
Posted: Fri Nov 09, 2012 2:45 pm
by Chris Peterson
saturno2 wrote:GRB 090423 is a object super distant, wich exploded just
630 million years after Big Bang.
The age of Universe 13,700 million of years
Distance of GRB 090423
13,700 - 630 = 13,300 million of light years
Not could to be a supernova, because the stars were in
formation.
What were this object?
A supernova. There's no reason to think that stars were not present when the Universe was 630 million years old.
BTW, you should be careful with distance calculations, since "distance" has multiple interpretations. The light travel time was 13.04 Gyr, but the comoving radial distance is 30 Gly. The best way to characterize this object is by its redshift, z=8.2, and by its age after the Big Bang, 0.63 Gyr.
Re: GRB 090423
Posted: Sat Nov 10, 2012 1:04 am
by saturno2
Chris Peterson is right
I have to make a precision
At the time of the explosion of GRB 090423, the distance from
Earth to that object was of 13.3 billion light years.
But Universe is expanding and GRB 090423 away from
Earth.
Re: GRB 090423
Posted: Mon Nov 12, 2012 5:37 pm
by Ann
It is likely that GRB 090423 was a particularly powerful supernova, produced by an extremely massive star. I hope Chris will correct me if I am wrong (which I may well be) but I believe that typical nearby core-collapse supernovae are usually set off by about ten solar masses worth of iron core (or less). In the distant past, when most gamma-ray bursts seem to happen, stars that went supernova may typically have started out with a hundred solar masses or so. Also, these long-ago stars had a different chemical makeup than most of today's stars. The ancient stars were typically metal-poor, which may have resulted in a milder stellar wind. So the stars may have retained more of their atmospheres as well as growing larger cores, making the eventual supernova explosion that much bigger and brighter.
Ann