NGC7331 and the Deer Lick Group
NGC 7331 is a spiral galaxy about 49 million light-years distant in the northern constellation Pegasus.
The background galaxies around NGC7331 (NGC 7337 NGC 7340, NGC 7335, NGC 7336..see inverted
image below) are about one tenth the apparent size and so may lie roughly ten times farther away (i.e.,
500 million light years away!). Their strikingly close alignment from our point of view occurs just by
chance. This visual grouping of galaxies is also known as the Deer Lick Group. Reportedly this name is
in honor of Deer Lick Gap in the mountains of North Carolina where the individual that coined this name
observed and once had an especially fine view of this group of galaxies.
The central bulge of NGC7331 is very unusual in that it appears to counter rotate relative to the outer
disk (i.e., it may turn in the opposite direction). The central bulge may have formed from in-falling
material from a colliding galaxy. The distance to NGC7331 was determined as part of the Hubble Space
Telescope Extragalactic Distance Scale Key Project which used the HST to obtain an accurate distance
via Cepheid variables. It was determined this galaxy is 49 million light years away and perhaps 130,000
light years across.
This galaxy has been the subject of several Astronomy Pictures of the Day, the most recent being on
October 24, 2009. Also, NGC7331 is very close to another group of galaxies known as the Stephan's
Quintet.
The color image shown below was formed from frames taken through 4 filters (clear, red, green and
blue). The images were then colorized and combined to give this image (13 x 10 min luminance, binned
1:1; 5 x 5 min, binned 2:2 each for RGB; ST10XME camera with AO8 adaptive optics guiding, C9.25 at
f/5). Thanks to Fred Pilcher for helping me with the galaxy identification.
The background galaxies around NGC7331 (NGC 7337 NGC 7340, NGC 7335, NGC 7336..see inverted
image below) are about one tenth the apparent size and so may lie roughly ten times farther away (i.e.,
500 million light years away!). Their strikingly close alignment from our point of view occurs just by
chance. This visual grouping of galaxies is also known as the Deer Lick Group. Reportedly this name is
in honor of Deer Lick Gap in the mountains of North Carolina where the individual that coined this name
observed and once had an especially fine view of this group of galaxies.
The central bulge of NGC7331 is very unusual in that it appears to counter rotate relative to the outer
disk (i.e., it may turn in the opposite direction). The central bulge may have formed from in-falling
material from a colliding galaxy. The distance to NGC7331 was determined as part of the Hubble Space
Telescope Extragalactic Distance Scale Key Project which used the HST to obtain an accurate distance
via Cepheid variables. It was determined this galaxy is 49 million light years away and perhaps 130,000
light years across.
This galaxy has been the subject of several Astronomy Pictures of the Day, the most recent being on
October 24, 2009. Also, NGC7331 is very close to another group of galaxies known as the Stephan's
Quintet.
The color image shown below was formed from frames taken through 4 filters (clear, red, green and
blue). The images were then colorized and combined to give this image (13 x 10 min luminance, binned
1:1; 5 x 5 min, binned 2:2 each for RGB; ST10XME camera with AO8 adaptive optics guiding, C9.25 at
f/5). Thanks to Fred Pilcher for helping me with the galaxy identification.
| NGC7331 and the Deer Lick Group Click on the image for a larger view |
| Inverse image showing the identification of the Deer Lick Galaxies Click on the image for a larger view |
