by Ann » Mon Jun 25, 2012 4:27 pm
This is an unusually fine image, thanks to the fact that it was taken through three different filters: one blue, one clear optical and one infrared one. The use of the blue filter makes it possible to look for young stars in this very small galaxy.
Indeed there are young stars here, but they are all limited to the "upper right quadrant" of the galaxy, to the upper right of the bright foreground star. It is remarkable how the "lower" part of the galaxy is totally devoid of blue stars, even though there is a good population of old yellowish and reddish stars.
It is not unusual that the star formation of a galaxy is concentrated in a few small parts of it. Here, there is one "extended region" that sees all of the action. The rest of the galaxy is "dead".
The star formation that actually goes on is noteworthy but not remarkable. This is most certainly not a starburst galaxy. The B-V index of this galaxy is +0.80, which is in fact moderately red. All the old stars of UGC 5692 are making their impact here. But the U-B index of the galaxy is +0.07, which is blue enough that it clearly speaks of the presence of some hot blue stars.
Ann
This is an unusually fine image, thanks to the fact that it was taken through three different filters: one blue, one clear optical and one infrared one. The use of the blue filter makes it possible to look for young stars in this very small galaxy.
Indeed there are young stars here, but they are all limited to the "upper right quadrant" of the galaxy, to the upper right of the bright foreground star. It is remarkable how the "lower" part of the galaxy is totally devoid of blue stars, even though there is a good population of old yellowish and reddish stars.
It is not unusual that the star formation of a galaxy is concentrated in a few small parts of it. Here, there is one "extended region" that sees all of the action. The rest of the galaxy is "dead".
The star formation that actually goes on is noteworthy but not remarkable. This is most certainly not a starburst galaxy. The B-V index of this galaxy is +0.80, which is in fact moderately red. All the old stars of UGC 5692 are making their impact here. But the U-B index of the galaxy is +0.07, which is blue enough that it clearly speaks of the presence of some hot blue stars.
Ann