rudykokich
Five Interacting Galaxies, Hickson 56 Compact Galaxy Group (HCG 56, Arp 322) Ursa Major
Five Interacting Galaxies, Hickson 56 Compact Galaxy Group (HCG 56, Arp 322) Ursa Major
In 1982, Canadian astronomer Paul Hickson published a study of 100 compact galaxy groups visible from the northern hemispere. The best known entries are HCG 44 (Hickson Compact Group 44), HCG 56 quintet, Copeland's Septet (57), The Box (61), Seyfert's Sextet (79), Stephan's Quintet (92)
ui.adsabs.harvard.edu/abs/1982ApJ...255..382H/abstract
Kinematic studies suggest that such crowded clusters are dynamically dominated by immense halos of dark matter where each member galaxy forms within its own subhalo, or a dark matter overdensity. Since the galaxies are gravitationally tightly bound, they manifest strong tidal interactions in the form of morphological deformation, elevated star formation rates, active galactic nucleus activity, and galaxy mergers. It is expected that the ultimate destiny of such groups is a merger into giant elliptical galaxies.
Unfortunately, most of these groups are too distant, small, and featureless to be of aesthetic interest in modest telescopes. HCG 44 is one of few exceptions, and you can see my image here:
www.cloudynights.com/topic/735825-hickson-44-compact-gala...
HCG 56 is a tight group of five interacting galaxies lying at a light travel distance of approximately 370 million light years, and receding from us due to the expansion of space at 8,000 km/sec. The galaxies are situated within a volume of about 15 million LY in diameter, and will over time merge into a giant elliptical galaxy. The attached highly cropped image does not show much internal detail, but does contain sufficient information for several observations. For example, light blue color in galaxies B, C, E (and ?D) is evidence of numerous hot, massive stars recently formed during starburst activity triggered by gravitational interaction. Galaxies C and D appear to be actively merging. Galaxy B has a long tidal stream extending toward C. And, all galaxies except A seem to have large, asymmetric halos. Literature review reveals that galaxies B and D are strong radio sources, while A and D have active galactic nuclei of the Seyfert type. When the photons we are presently observing were emitted, about 370 million years ago, Earth was undergoing the Late Devonian Extinction event which obliterated 80% of all marine species. From the photons' perspective, time does not pass when travelling at the speed of light, and the journey was instantaneous.
Three distant galaxies are identified in the annotated image, and listed in the chart below. The most remote is quasar SDSS J113228.23+525328.8, located at light travel distance of 11.1 billion light years, or proper distance (in the present epoch) of 19.5 billion LY. When the photons were emitted, the quasar was receding at 256,102 km/s, while at the present time it is estimated to be receding at superluminal 422,004 km/s. With absolute magnitude of -29.63, it is about 3,400 times brighter than the entire Milky Way galaxy. 99.38% of its light is extincted, or literally diluted by the expansion of the intervening space.
Image Details:
Meade 8'' ACF, AP 0.7x compressor, 200 x 1400 mm
iEQ30pro mount, Orion 60mm f/4 SSAGpro autoguider
Canon T3i modified camera, Astronomik L3 filter
29 x 300 sec subs (7 discarded), iso 1600, 30 darks, 30 bias, 2x drizzle, 20% linear crop
Software: PHD2, DSS, XnView, StarNet++, StarTools.
Five Interacting Galaxies, Hickson 56 Compact Galaxy Group (HCG 56, Arp 322) Ursa Major
Five Interacting Galaxies, Hickson 56 Compact Galaxy Group (HCG 56, Arp 322) Ursa Major
In 1982, Canadian astronomer Paul Hickson published a study of 100 compact galaxy groups visible from the northern hemispere. The best known entries are HCG 44 (Hickson Compact Group 44), HCG 56 quintet, Copeland's Septet (57), The Box (61), Seyfert's Sextet (79), Stephan's Quintet (92)
ui.adsabs.harvard.edu/abs/1982ApJ...255..382H/abstract
Kinematic studies suggest that such crowded clusters are dynamically dominated by immense halos of dark matter where each member galaxy forms within its own subhalo, or a dark matter overdensity. Since the galaxies are gravitationally tightly bound, they manifest strong tidal interactions in the form of morphological deformation, elevated star formation rates, active galactic nucleus activity, and galaxy mergers. It is expected that the ultimate destiny of such groups is a merger into giant elliptical galaxies.
Unfortunately, most of these groups are too distant, small, and featureless to be of aesthetic interest in modest telescopes. HCG 44 is one of few exceptions, and you can see my image here:
www.cloudynights.com/topic/735825-hickson-44-compact-gala...
HCG 56 is a tight group of five interacting galaxies lying at a light travel distance of approximately 370 million light years, and receding from us due to the expansion of space at 8,000 km/sec. The galaxies are situated within a volume of about 15 million LY in diameter, and will over time merge into a giant elliptical galaxy. The attached highly cropped image does not show much internal detail, but does contain sufficient information for several observations. For example, light blue color in galaxies B, C, E (and ?D) is evidence of numerous hot, massive stars recently formed during starburst activity triggered by gravitational interaction. Galaxies C and D appear to be actively merging. Galaxy B has a long tidal stream extending toward C. And, all galaxies except A seem to have large, asymmetric halos. Literature review reveals that galaxies B and D are strong radio sources, while A and D have active galactic nuclei of the Seyfert type. When the photons we are presently observing were emitted, about 370 million years ago, Earth was undergoing the Late Devonian Extinction event which obliterated 80% of all marine species. From the photons' perspective, time does not pass when travelling at the speed of light, and the journey was instantaneous.
Three distant galaxies are identified in the annotated image, and listed in the chart below. The most remote is quasar SDSS J113228.23+525328.8, located at light travel distance of 11.1 billion light years, or proper distance (in the present epoch) of 19.5 billion LY. When the photons were emitted, the quasar was receding at 256,102 km/s, while at the present time it is estimated to be receding at superluminal 422,004 km/s. With absolute magnitude of -29.63, it is about 3,400 times brighter than the entire Milky Way galaxy. 99.38% of its light is extincted, or literally diluted by the expansion of the intervening space.
Image Details:
Meade 8'' ACF, AP 0.7x compressor, 200 x 1400 mm
iEQ30pro mount, Orion 60mm f/4 SSAGpro autoguider
Canon T3i modified camera, Astronomik L3 filter
29 x 300 sec subs (7 discarded), iso 1600, 30 darks, 30 bias, 2x drizzle, 20% linear crop
Software: PHD2, DSS, XnView, StarNet++, StarTools.