Talleyrand wrote:Bare with me for a dumb question...
Re the Halo image: the text indicated that in three million years there would be a supernova...
Supernovas can be seen presumably easily due to their huge energy output...so,
If there are a 100B stars (OK, not all will be the type to blow) in 100B galaxies and the Universe if about 15BYO...
Shouldn't we be seeing supernovas all the time?
Let's just concentrate on the Milky Way which has ~ 300B stars
I'm guessing than only about 1 in a million stars is a short lived supergiant
(i.e., an average distance of ~400 lyrs vs. ~4 lyrs.)
So the Milky Way has ~ 300,000 short lived supergiants with an average life of 15M yrs.
Hence, a Milky Way supernova should occur about once every 50 yrs. (= 15M yrs./300,000).
A careful monitoring of 50 big galaxies should yield about one supernova a year.
Note, however, that a systematic careful monitoring of other galaxies for un-obscured supernova is a fairly recent phenomenon.
[quote="Talleyrand"]Bare with me for a dumb question...
Re the Halo image: the text indicated that in three million years there would be a supernova...
Supernovas can be seen presumably easily due to their huge energy output...so,
If there are a 100B stars (OK, not all will be the type to blow) in 100B galaxies and the Universe if about 15BYO...
Shouldn't we be seeing supernovas all the time? [/quote]
Let's just concentrate on the Milky Way which has ~ 300B stars
I'm guessing than only about 1 in a million stars is a short lived supergiant
(i.e., an average distance of ~400 lyrs vs. ~4 lyrs.)
So the Milky Way has ~ 300,000 short lived supergiants with an average life of 15M yrs.
Hence, a Milky Way supernova should occur about once every 50 yrs. (= 15M yrs./300,000).
A careful monitoring of 50 big galaxies should yield about one supernova a year.
Note, however, that a systematic careful monitoring of other galaxies for un-obscured supernova is a fairly recent phenomenon.