by Ann » Fri Oct 25, 2013 6:53 pm
Wow, this thread has become so extremely interesting while I was away! Thanks to everyone who chipped in with observations and comments on background galaxies and dwarf galaxies!
Thanks in particular to Ken Crawford, for sharing your raw data frame with us, and to Rob, for your splendid pixellating talents and your great job bringing out background galaxies and companion galaxies. In my completely amateur opinion, the three galaxies that you brought out so beautifully for us
here likely all belong to the same group and are locked in a common tidal embrace, just like BDanielMayfield suggested.
Oh, and Rob - I love
that orange and blue pair, just like you thought I would!
On the other hand, I don't think I agree with you when you guessed that
this galaxy may be a background object, considerably more distant than NGC 7814. The galaxy is faint and "soft", and it lacks the sharply defined central brightening that we would expect from a major galaxy. Therefore I believe it is a dwarf galaxy, although it may be larger than the other companions of NGC 7814. Note this galaxy's blue color, which is much bluer than the color of the dwarf galaxy directly "below" NGC 7814. This galaxy must have had some recent star formation. On the other hand, its star formation could have ceased by now, leaving behind a slowly dispersing and moderately but not very bright and blue population of A-type stars like Sirius and Vega. The structure of this galaxy, by the way, is similar to what the Large Magellanic Cloud would have looked like if its star formation had ceased after the formation of its bar. Fascinatingly, there is just a hint of of
a polar ring around this galaxy. So if it is a polar ring galaxy, does that make it big? No, not necessarily. The polar ring galaxy I just linked to is less than half as bright as the Milky Way, according to my software. But that galaxy is much yellower and has a much more definite structure than the galaxy here.
Ann
Wow, this thread has become so extremely interesting while I was away! Thanks to everyone who chipped in with observations and comments on background galaxies and dwarf galaxies! :D
Thanks in particular to Ken Crawford, for sharing your raw data frame with us, and to Rob, for your splendid pixellating talents and your great job bringing out background galaxies and companion galaxies. In my completely amateur opinion, the three galaxies that you brought out so beautifully for us [url=http://asterisk.apod.com/viewtopic.php?p=212070#p212070]here[/url] likely all belong to the same group and are locked in a common tidal embrace, just like BDanielMayfield suggested.
Oh, and Rob - I love [url=http://asterisk.apod.com/viewtopic.php?p=212071#p212071]that orange and blue pair[/url], just like you thought I would! :D
On the other hand, I don't think I agree with you when you guessed that [url=http://asterisk.apod.com/viewtopic.php?p=212088#p212088]this galaxy[/url] may be a background object, considerably more distant than NGC 7814. The galaxy is faint and "soft", and it lacks the sharply defined central brightening that we would expect from a major galaxy. Therefore I believe it is a dwarf galaxy, although it may be larger than the other companions of NGC 7814. Note this galaxy's blue color, which is much bluer than the color of the dwarf galaxy directly "below" NGC 7814. This galaxy must have had some recent star formation. On the other hand, its star formation could have ceased by now, leaving behind a slowly dispersing and moderately but not very bright and blue population of A-type stars like Sirius and Vega. The structure of this galaxy, by the way, is similar to what the Large Magellanic Cloud would have looked like if its star formation had ceased after the formation of its bar. Fascinatingly, there is just a hint of of [url=http://heritage.stsci.edu/1999/16/index.html]a polar ring[/url] around this galaxy. So if it is a polar ring galaxy, does that make it big? No, not necessarily. The polar ring galaxy I just linked to is less than half as bright as the Milky Way, according to my software. But that galaxy is much yellower and has a much more definite structure than the galaxy here.
Ann