by Ann » Sun Jul 31, 2011 7:35 am
Adam, I wish I could reproduce your image in my post, so that it would be easier to discuss it. I will try to talk about it anyway.
The Hercules Cluster is a remarkable galaxy cluster, because it is so rich in spirals and obviously interacting galaxies. This means, I think, that the Hercules Cluster is young as a cluster, because otherwise the galaxies would have been "shorn" of their spiral arms and long tidal tails.
I'll try to talk about the picture from top to bottom. The top part of it contains, in the right-hand corner, a remarkable interacting pair of elliptical galaxies. These two galaxies, IC 1178 och IC 1181, lack gas and star formation, but they are throwing out huge tails of old yellow stars. This kind of interaction and merging of gas-free galaxies are called "dry mergers". They don't produce any star formation. However, it is likely that remnants of these thrown-out tails of yellow stars leave behind faint arcs or shells, which are often seen around giant elliptical galaxies.
If you move down to just above the middle part of the picture and go to the left edge of the image, you can see another interacting pair. These are NGC 6040A and 6040B. These two galaxies are undergoing a "wet merger" with gas and star formation. The face-on galaxy doesn't have much gas, but you can see faint blue shells of young stars surronding the bright yellow bulge of the galaxy. The edge-on galaxy has spiral arms, or possibly a broken "ring", of bright blue star formation regions. The edge-on galaxy is clearly distorted because of the merger.
Now let's go to the "mid-plane" of the picture. Almost in the dead center of it, just a little bit to the right, is one of the most famous denizens of the Hercules Cluster. That is galaxy NGC 6045A, the gently "undulating" spiral galaxy with a yellow inner region and outer blue arms. But the most fascinating thing about NGC 6045A is that it appears to "balance" a small edge-on galaxy on its "foot", or "nudge it" with its "foot"! Like a soccer player! Well, if you ask me, the small edge-on galaxy, NGC 6045B, is probably a background object, which is not directly interacting with NGC 6045A. But what a pair they are, nevertheless!
Now move to the right of NGC 6045, and you'll come to what is probably
the most famous members of the Hercules Cluster, NGC 6050A and NGC 6050B. In this famous Hubble Telescope picture of NGC 6050, you can see that it consist of threes, possibly
four interacting galaxies!!! There is a small galaxy tangled in the spiral arms below the main interacting pair. And there is even what looks like a fourth galaxy to the left of the third one! Where is the "jawdrop" smilie?
Note how one of the two large galaxies is producing huge clusters of newborn massive stars, so called super star clusters. Note that this galaxy doesn't really seem to have a nucleus, only a bar running between its two main spiral arms! The other large galaxy is clearly more massive. It has a large bulge, an obvious nucleus and well-formed arms.
To the lower right of the NGC 6050 triplet (or quartet???) in Adam Block's image, you can see an oblong blue and yellow galaxy, surrounded by a somewhat misshapen ring. My software refuses to give this galaxy a name, other than, perhaps, PGC 57077. I am the owner of a book, "The Color Atlas of Galaxies", whose author, James D Wray, was amazed at PGC 57077, which he mistakenly called NGC 6054. (That is another galaxy.) James D Wray wrote about PGC 57077:
NGC 6054 [PGC 57077] is the galaxy at lower left [at lower left in his own photo of it] with the extraordinary blue bar. There are practically no galaxies with bars similar to this...
So the bar of PGC 57077, with its extremely bright blue bar-ends, is remarkable.
Now move down a bit in the picture and go slightly to the right, until you come to a galaxy with a long blue jet. At an angle of a bit more than 90 degrees to this jet, there is another jet, ending in a big arc-shaped bow shock. The galaxy is IC 1182. And if the bar of PGC 57077 is remarkable, then the (main) jet of IC 1182 is sure remarkable, too! The jet of M87, seen here in a famous Hubble picture, has nothing on the jet of IC 1187! Well, I guess it does after all, because M87 is a much, much bigger galaxy than IC 1187, so it is possible that the respective jets of these two galaxies are of a similar size. Still, the jet of IC 1187 is truly remarkable, and not less so because the galaxy obviously has another jet, too.
So all in all, Adam Block has given us a remarkable portrait of a remarkable galaxy cluster. I hope that many people here will keep scrutinizing the image on their own, because there are still more things to see in this amazing photo of a galaxy zoo!
Ann
Adam, I wish I could reproduce your image in my post, so that it would be easier to discuss it. I will try to talk about it anyway.
The Hercules Cluster is a remarkable galaxy cluster, because it is so rich in spirals and obviously interacting galaxies. This means, I think, that the Hercules Cluster is young as a cluster, because otherwise the galaxies would have been "shorn" of their spiral arms and long tidal tails.
I'll try to talk about the picture from top to bottom. The top part of it contains, in the right-hand corner, a remarkable interacting pair of elliptical galaxies. These two galaxies, IC 1178 och IC 1181, lack gas and star formation, but they are throwing out huge tails of old yellow stars. This kind of interaction and merging of gas-free galaxies are called "dry mergers". They don't produce any star formation. However, it is likely that remnants of these thrown-out tails of yellow stars leave behind faint arcs or shells, which are often seen around giant elliptical galaxies.
If you move down to just above the middle part of the picture and go to the left edge of the image, you can see another interacting pair. These are NGC 6040A and 6040B. These two galaxies are undergoing a "wet merger" with gas and star formation. The face-on galaxy doesn't have much gas, but you can see faint blue shells of young stars surronding the bright yellow bulge of the galaxy. The edge-on galaxy has spiral arms, or possibly a broken "ring", of bright blue star formation regions. The edge-on galaxy is clearly distorted because of the merger.
Now let's go to the "mid-plane" of the picture. Almost in the dead center of it, just a little bit to the right, is one of the most famous denizens of the Hercules Cluster. That is galaxy NGC 6045A, the gently "undulating" spiral galaxy with a yellow inner region and outer blue arms. But the most fascinating thing about NGC 6045A is that it appears to "balance" a small edge-on galaxy on its "foot", or "nudge it" with its "foot"! Like a soccer player! Well, if you ask me, the small edge-on galaxy, NGC 6045B, is probably a background object, which is not directly interacting with NGC 6045A. But what a pair they are, nevertheless!
[float=right][img]http://regmedia.co.uk/2008/04/24/colliding_galaxies.jpg[/img][/float]Now move to the right of NGC 6045, and you'll come to what is probably [i]the[/i] most famous members of the Hercules Cluster, NGC 6050A and NGC 6050B. In this famous Hubble Telescope picture of NGC 6050, you can see that it consist of threes, possibly [i]four[/i] interacting galaxies!!! There is a small galaxy tangled in the spiral arms below the main interacting pair. And there is even what looks like a fourth galaxy to the left of the third one! Where is the "jawdrop" smilie?
Note how one of the two large galaxies is producing huge clusters of newborn massive stars, so called super star clusters. Note that this galaxy doesn't really seem to have a nucleus, only a bar running between its two main spiral arms! The other large galaxy is clearly more massive. It has a large bulge, an obvious nucleus and well-formed arms.
To the lower right of the NGC 6050 triplet (or quartet???) in Adam Block's image, you can see an oblong blue and yellow galaxy, surrounded by a somewhat misshapen ring. My software refuses to give this galaxy a name, other than, perhaps, PGC 57077. I am the owner of a book, "The Color Atlas of Galaxies", whose author, James D Wray, was amazed at PGC 57077, which he mistakenly called NGC 6054. (That is another galaxy.) James D Wray wrote about PGC 57077:
[quote]NGC 6054 [i][PGC 57077][/i] is the galaxy at lower left [i][at lower left in his own photo of it][/i] with the extraordinary blue bar. There are practically no galaxies with bars similar to this...[/quote]
So the bar of PGC 57077, with its extremely bright blue bar-ends, is remarkable.
[float=right][img]http://upload.wikimedia.org/wikipedia/commons/thumb/3/39/M87_jet.jpg/220px-M87_jet.jpg[/img][/float]
Now move down a bit in the picture and go slightly to the right, until you come to a galaxy with a long blue jet. At an angle of a bit more than 90 degrees to this jet, there is another jet, ending in a big arc-shaped bow shock. The galaxy is IC 1182. And if the bar of PGC 57077 is remarkable, then the (main) jet of IC 1182 is sure remarkable, too! The jet of M87, seen here in a famous Hubble picture, has nothing on the jet of IC 1187! Well, I guess it does after all, because M87 is a much, much bigger galaxy than IC 1187, so it is possible that the respective jets of these two galaxies are of a similar size. Still, the jet of IC 1187 is truly remarkable, and not less so because the galaxy obviously has another jet, too.
So all in all, Adam Block has given us a remarkable portrait of a remarkable galaxy cluster. I hope that many people here will keep scrutinizing the image on their own, because there are still more things to see in this amazing photo of a galaxy zoo! :D
Ann