Abell 1367 - The Leo Galaxy Cluster

Higher resolutions: normal 4000x4000 (100%, more aesthetic), Inverted 4000x4000 (100%, enhanced visibility)

About this Image

Subject Abell 1367 - The Leo Galaxy Cluster
Objects Major members: NGC 3842, NGC 3883, NGC 3884, NGC 3861A and B, NGC 3837, UGC 6697, NGC 3862, NGC 3864, and many smaller galaxies.
Data NED database entry
Description At 280 million light years distant the Leo cluster is around the same distance from the Milky Way as the Coma cluster (Abell 1656), and together they make up the bulk of the Coma supercluster. The supercluster is part of a string of clusters including the neighboring Hercules cluster that in turn make up a huge sheet of galaxies known as the Coma Great Wall. The Great Wall is just one of the larger aglomerations of galaxy clusters that shape the three dimensional spider's web of filaments and sheets surrounding vast empty voids - creating the foam like structure of our universe at the largest scales. NGC 3842 and Quasars

NGC 3842 is one of the two large eliptical galaxies that dominate the center of the cluster. Around the galaxy are arrayed three quasars. These quasars were used as "evidence" by Halton Arp to bolster his theory that quasars are ejected from the cores of galaxies, and not cosmological objects. This theory has been completely sidelined in modern cosmology due to several lines of complementary evidence for these objects being at cosmological distances. The accepted view is that these immensely bright and distant objects are powered by supermassive blackhole accretion disks. One of the quasars in this image ([VV96] J114405.3+195603), a 21st magnitude object, exhibits a red shift of z2.2. This equates to a distance of 10.3 billion light years - by far (sic) the most distant object that I am aware of capturing in one of my images. Due to its distance and the expansion of space, it is travelling away from us at 246,449 km/s - more than 80% the speed of light.

There are several "long tailed" spiral galaxies in the Leo cluster, the most prominent being UGC 6697 located to right of and roughly pointing towards the large eliptical NGC 3842. These infalling galaxies tend to exhibit enhanced star formation on their cluster facing side and tails of stripped gas pointing away from the cluster, both effects resulting from ram pressure with the intracluster medium. Over longer periods this results in reduced star formation rates for galaxies within this "hot" zone as their gas is stripped away. The center of typical galaxy clusters are dominated by old eliptical galaxies. It is thought that the high incidence of galaxy collisions and mergers tends to result in the formation of large eliptical galaxies. The Leo cluster is not typical in this respect and has a higher ratio of spirals to elipticals than most, and for this reason it is believed to have formed relatively recently.

Technical Details

Date 2009 03 20-23
Location Pumpkin Patch Observatory, Bourn, Cambridge, UK
Environment ~3-7C, 85-95% humidity, no moon
Optics Astro Optik 400mm Cassegrain @ prime focus (f=1200mm)
Filters Astrodon L, YR Cyclops filter wheel
Mount Paramount ME
Guiding Borg 101ED/SBIG ST402ME
Camera FLI Microline 16803
Exposure 4hrs 20minutes, 5 minute subs
Processing Maxim/DL 5, CCDStack, Photoshop CS
Notes Taken after system optical tilt diagnosed to be due to non-orthogonal CCD mounting, and fixed with shims made from slices from a can of 7-UP. Collimation still to be completely dialed-in. First set of images with Borg guidescope attached. Dithered. CCD setpoint 0C to avoid CCD window condensation issues (prior to heater fix).
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