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 ascension	20^h 48^m 11.9s^s[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	20^h 48^m 15.0^s	−19° 50′ 58″	8443 ± 14	15.3
HCG 87b	SA(r)0 pec	20^h 48^m 10.9^s	−19° 51′ 23″	8740 ± 20	15.4
HCG 87c	Sb	20^h 48^m 12.0^s	−19° 49′ 56″	8914 ± 7	16.1
HCG 87d	Sd	20^h 48^m 12.8^s	−19° 50′ 46″	10200 ± 160	17.8

External links

• Astronomy Picture of the Day
  • Galaxy Group HCG 87 - 2003 July 31
  • HCG 87: A Small Group of Galaxies - 2010 July 6
• Close-ups of HCG 87
• Galactic Clusters
• Studies of Hickson Compact Groups

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.