Expert: Tom Whiting - 1/26/2008

Question
Although they may have existed at one time, is there any way
to prove that stars that are more than 6000 light years away
STILL exist? If it takes the light from a star more than 6000 years to get to earth how do we know they are still there?

Answer
Hi Raven,
I have pulled this question from the question pool, so please don't
penalize me for time...I think they only post them once a month
for us to peruse.
We know stars, even the shortest lived stars which are the massive
blue-white supergiants, have lifespan of 10's of millions of years.
They all end up going supernova - exploding.
{This IS very short, compared to the solar-type stars with lifespans
like our sun, of 8-10 billion years, or little red dwarf stars
(the most common star) with lifespans of several Trillion years}.

So while no one could guarantee that a star, say 6000-10,000 lightyears distant, is no longer functional, the odds are in favor of it still being there because of the vast lifespan of the stars
themselves.  Also, if you're referring to a normal main sequence star, the next step of evolution would be the Red Giant phase, followed by the planetary nebula stage, followed by the white dwarf stage, each of these stages requiring several million years to go through and live out those particular later stages of stellar life.  So your "6000" lightyear star could be moving into another stage of stellar evolution, but the odds are pretty good that it is still there, as 6000 years is only a "few seconds" on the cosmological time scale of millions and billions of years.
Hope this helps,
Clear Skies,
Tom Whiting
Erie, PA

BTW, 6000 lightyears doesn't even get you out of our spiral arm
of the Milky Way Galaxy...that's our "neighbors"...our Milky Way
extends to a disk 100,000 light years across, and it's not even
the biggest galaxy.  Our neighbor, the Andromeda Galaxy, is some
2.5 million light years distant, and is nearly 20% bigger than us.
And that's still part of the Local Group of 30 odd galaxies within
a 5 million lightyear radius, and the Local Group is part, and orbiting, the Virgo Supercluster, some thousands of galaxies including M-84, 86, and 87, some 65 million light years
distant in Virgo.  So your....6000 light years, is not even a
"drop in the bucket"...as they say....doesn't even get you out of
our own spiral arm, the Orion Arm, of the Milky Way Galaxy.
Clear Skies,
Tom Whiting
Erie, PA