HCG 87

HCG 87 is a compact group of galaxies listed in the Hickson Compact Group Catalogue. This group is about 400 million light-years away [2] in the constellation Capricornus. The group distinguishes itself as one of the most compact groups of galaxies, hosting two active galactic nuclei and a starburst among its three members, all of which show signs of interaction.[3] This interaction, which astronomers have called visually, and scientifically, intriguing[4] is being examined to understand the influence of active nuclei on star formation histories.

HCG 87
Galaxy Group HCG 87
Observation data (Epoch )
Constellation(s)Capricornus
Right ascension20h 48m 11.9ss[1]
Declination−19° 50′ 35″[1]
Number of galaxies~5
Distance
(co-moving)		400 million
Other designations
None

Members
Members of the HCG 87
Name Type[5] R.A. (J2000)[5] Dec. (J2000)[5] Redshift (km/s)[5] Apparent Magnitude[5]
HCG 87a S0 pec 20h 48m 15.0s −19° 50′ 58″ 8443 ± 14 15.3
HCG 87b SA(r)0 pec 20h 48m 10.9s −19° 51′ 23″ 8740 ± 20 15.4
HCG 87c Sb 20h 48m 12.0s −19° 49′ 56″ 8914 ± 7 16.1
HCG 87d Sd 20h 48m 12.8s −19° 50′ 46″ 10200 ± 160 17.8

References
  1. "NASA/IPAC Extragalactic Database". Results for HCG 87. Retrieved 2006-10-19.
  2. This redshift corresponds to a distance of 120Mpc or 400 million light years (using H0 = 75km/s/Mpc and q0 = 0.1). At the distance of the group, this corresponds to a group diameter of 52kpc, i.e., the group is approximately 170,000 light years across.
  3. Noll, Keith. 07/1999. "Hubble Heritage observations of Hickson Compact Galaxy Group 87".
  4. English, J. et al. 05/2000. "A Minuet of Galaxies: Hickson Compact Group 87 as Viewed by the Hubble Space Telescope". American Astronomical Society, 195th AAS Meeting, #136.04; Bulletin of the American Astronomical Society, Vol. 32, p.884.
  5. "NASA/IPAC Extragalactic Database". Results for various galaxies. Retrieved 2006-10-19.



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