M100 is one of my favourite galaxies, and I'm very glad that Hubble has re-visited it!
An interesting thing about M100 is the extremely bright blue ring surrounding the even brighter yellow center. When you look closely at this nuclear ring, however, it doesn't resolve well into individual stars. My interpretation is that the nuclear ring of M100 is a post-starburst feature, which is to say that it used to be even brighter. Just think how brilliant it must have been in its prime!
(Of course... another possibility is that this ring has experienced "one small starburst after another" which has left huge numbers of bluish and "sort of bright" stars behind.)
Another interesting thing about M100 is that it is about to turn into a barred spiral. (Some astronomers may say that it is barred already.) Well, you can't really
see the bar, and there is no yellow brightening stretching more or less straight across the bulge. (In some barred spiral galaxies, the bar is so dominant that it
is the bulge.
But the two dark dust lanes of M100 winding their way from the "spiral disk" all the way into the nucleus are a dead giveaway that we are dealing with a barred galaxy, or at least a barred-galaxy-to-be. The brilliant nuclear ring is very typical of barred spiral galaxies, too.
So maybe M100 is showing us the transitional stage from non-barred to barred spiral galaxies!
Ann
M100 is one of my favourite galaxies, and I'm very glad that Hubble has re-visited it! :D
An interesting thing about M100 is the extremely bright blue ring surrounding the even brighter yellow center. When you look closely at this nuclear ring, however, it doesn't resolve well into individual stars. My interpretation is that the nuclear ring of M100 is a post-starburst feature, which is to say that it used to be even brighter. Just think how brilliant it must have been in its prime!
(Of course... another possibility is that this ring has experienced "one small starburst after another" which has left huge numbers of bluish and "sort of bright" stars behind.)
Another interesting thing about M100 is that it is about to turn into a barred spiral. (Some astronomers may say that it is barred already.) Well, you can't really [i]see[/i] the bar, and there is no yellow brightening stretching more or less straight across the bulge. (In some barred spiral galaxies, the bar is so dominant that it [i]is[/i] the bulge.
But the two dark dust lanes of M100 winding their way from the "spiral disk" all the way into the nucleus are a dead giveaway that we are dealing with a barred galaxy, or at least a barred-galaxy-to-be. The brilliant nuclear ring is very typical of barred spiral galaxies, too.
So maybe M100 is showing us the transitional stage from non-barred to barred spiral galaxies!
Ann