This image was taken to celebrate
the 26th anniversary of Hubble's launch.
Every year, every anniversary, we try to find
a new image used to celebrate it so that over the years we've done
all sorts of objects from star clusters to nebulae to external galaxies.
But for the 26th, we chose this one.
This is the Bubble nebula, in the constellation
Cassiopeia, and it's about 7,100 light years distant from us.
I like this image because of the variety of things you can see in it.
Obviously, you've got the massive star at the center.
Big ring here is a bunch of material thrown off the star and it's
been able to travel out that far.
The star threw off
material relatively symmetrically around the star,
but the interstellar material is the preexisting material in the area around
the star was much denser on this side, which actually makes sense
because you've got this huge blob of material up here.
It makes sense that there's more material near that
and there is on this relatively empty spot at the bottom of the image.
So as the material came off the star, it runs into much denser material
going up to the upper left. And that A, slows it down.
So it's not going
as far in that direction. And B, heats it up, so it's glowing much more.
Whereas the material that came off to the bottom right didn't
run into very much.
So it's going unimpeded.
It's moving out faster and getting further away from the star,
and it's also not heating anything up.
So you're not seeing anything glow down in that region.
So it's a matter of what the material around the star was in one direction.
It was unimpeded and basically able to go out long distances.
In the other direction,
it ran into resistance right away and effectively couldn't go very far.
But it's giving us a nice light show in the process.
It's a pretty massive star.
We think it started out at about 60 times the mass of the sun,
and because it's been throwing off
material over time, it's lost about a quarter of that mass,
about 15 solar masses and is now down to about 45 solar masses.
Large stars like that have relatively short lives.
They're fast and furious, but they go through life very, very quickly.
Something like the sun last 10 billion years. Something like this.
you're talking tens of millions of years instead of billions of years.
So plenty of material left to go supernova.
You need a star to have something like 1.4 times
the mass of the sun, at least, before it's a candidate for a supernova.
So at 45 solar masses, it’s going to supernova, no question.