I love seeing big splashy NGC 7331 (which might have been a Messier galaxy if Messier had searched the skies a bit more diligently - maybe he didn't like highly inclined spiral galaxies, because he missed NGC 4565
NGC 7331 and the Deer Lick Group.
Photo: Vicent Peris/Calar Alto Observatory
A fascinating thing about NGC 7331 is that we can really see how the spiral arms end at one side of it. Look at those dancing feet of the galaxy at 5 o'clock in this image!
The Vicent Peris picture of NGC 7331 clearly contains details in not seen in today's APOD, but that is because today's APOD was taken through a much smaller instrument than the 3.5 meter Calar Alto Telescope that Vicent Peris had at his disposal. But before we leave Vicent Peris's image, consider the fascinating Deer Lick Group
of background galaxies! According to the link I just posted, the distance to the Deer Lick Group is about 500 million light-years. I particularly like the elegantly barred spiral galaxy NGC 7337
, which looks great in Vicent Peris' image.
Stephan's Quintet. NGC 7320C at far left. Photo: Robert Gendler/Judy Schmidt.
Yes, but today's APOD does something that Vicent Peris couldn't, namely, gives us an overview of the entire region to include Stephan's Quintet in the field. Again, the portrait of Stephan's Quintet isn't perfect in the APOD (compare it with the Gendler/Schmidt picture at right, which in the version I posted is far from full resolution), but it is good enough, and it gives us good structural and near-perfect overall color information about the group.
We can tell, from Péter Feltóti's image, that the elongated arm of NGC 7319
points at small spiral galaxy NGC 7320C, and we can conclude that NGC 7320C just might be at the same distance as NGC 7319 and be interacting with it. (But then again, it might not. I wonder if the center of NGC 7320C is yellow enough to be as far away and even nearly as bright as the "yellow members" of Stephan's Quintet. Also, the arms of NGC 7320C appear to be too undisturbed to be interacting with NGC 7319 and too well resolved, in spite of their very modest amount of star formation, to be at the same distance as the yellow members of Stephan's Quintet.
We can tell that the Deer Lick Group is yellower than Stephan's Quintet (even if we don't take blue NGC 7320 into consideration) and we can conclude that the Deer Lick group contains less star formation than Stephan's Quintet.
We can easily see that Stephan's Quintet is a terrifically compact group, whereas the Deer Lick Group is a lot more spread out. It would seem to me that the members of the deer Lick Group are larger then the ones of Stephan's Quintet.
We can tell that the disk of NGC 7320
(a 500 Kb image) is the same as the color of the disk of NGC 7331, and we can rightly conclude that NGC 7320 is at the same distance from us as NGC 7331, and that it a quite small dwarf spiral galaxy belonging to the NGC 7331 group.
But we can also tell that the small dim sort of grayish-blue object to the right of NGC 7331 is the right color and size for this object to be a dwarf spheroidal galaxy and a satellite of NGC 7331.
We can extract wonderful amounts of information from Péter Feltóti's image!