Draft:HCG 4
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HCG 4
[edit]| HCG 4 | |
|---|---|
 Hickson Compact Group 4 by Legacy Surveys Data Release 10 | |
| Observation data (Epoch J2000) | |
| Constellation | Cetus |
| Right ascension | 00h 34m 15.9s |
| Declination | −21° 26′ 48.0″ |
| Brightest member | ESO 540-1 |
| Number of galaxies | 5 |
| Velocity dispersion | 338.9 km/s |
| Redshift | 0.026915 |
| Distance | 114.52 Mpc (373.77 Mly) |
| Other designations | |
| SCG 0031-2143; SCG 05; HIPASS J0034-21 | |
Hickson Compact Group 4[1] is a compact group of galaxies that concludes of 5 members. In Constellation Cetus, HCG 4 was identified by a systematic search by the Palomar Observatory Sky Survey lead by Paul Hickson.[2] HCG 4 is a Compact Galaxy Group along with another 99 Groups detected by Paul Hickson. In HCG 4, HCG 4E is the furthest galaxy, which is 868.36 Million light-year away with a Velocity of 18480 km/s[3], followed by HCG 4C which is 871.56 Mly away. HCG 4B is the closest to Milky Way, followed by HCG 4A and 4D. HCG 4 has a Crossing time (H0tc) of 0.0126.[4] HCG 4 is a group that is relatively isolated due to it is not connected to any large nearby structures or any clusters.
Properties
[edit]HCG 4A has shown a strong infrared radiation from a Far-Infrared (FIR) study by Infrared Astronomy Satellite (IRAS)[5][6], reaching an amount of 10.957 L☉, HCG 4A also has the least B-R (Blue minus Red) and B_T (Total Blue Magnitude)[7][8], indicating to astronomers that HCG 4A has a massive amount of stellar nurseries and is undergoing vigorous star formation. HCG 4A falls under the Luminous Infrared Galaxy (LIRG) category, while HCG 4B, 4C and 4E has not been detected or their infrared radiation is low or weak, they have also high B-R and B_T, hinting that they are not actively forming stars and is likelihood to be dominated by cool and old stars.
HCG 4A is the brightest member of this group, as other studies suggests that HCG 4A has M_B (known as Absolute magnitude) of 21.1, following by HCG 4B, 4C and 4D, which has M_B of 19.3, 19.1 and 19.1 respectively. [9] An analysis of the environment around HCG 4 has been conducted, uncovering that there is a total of 12 background galaxies, 6 foreground stars. The study also a field density of 0.00184 galaxies per square arcminute outside the group. This survey proves that the group members are centrally concentrated with a radius of 3.5 arcminutes, while the nearest field galaxy is 14.8 arcminutes away, proving that HCG 4 is truly a compact group.[8]
Morphology
[edit]Studies has shown that HCG 4C has a disturbed morphology, often due to gravitational interaction with other galaxies that may be a sign of a pre-merger. Other than that, HCG 4D also has a disturbed morphology, has emission lines and is too blue, indicating a sign of a post merger and has high star formation.[6]
Another study suggests that out of 5 galaxies in HCG 4 group, there are a total of 3 galaxies are spirals.[10] Therefore, the spiral fraction (FSP) for this galaxy group is 0.6 or 60%.[10]
Members
[edit]Hickson Compact Group 4 consists of 5 members, HCG 4A to 4E, where their details are stated in the table below.
| Number | Other Names | Right | Declination | Distance | Type | B-R | B_T | Velocity (km/s)[3] | Redshift |
|---|---|---|---|---|---|---|---|---|---|
| 4A[11] | ESO 540-1 | 00h 34m 13.8212s | -21° 26' 20.578″ | 114.21 Mpc
(372.75 Mly) |
(R')SB(r)bc | 1.01 | 13.78 | 8097 | 0.026845 |
| 4B[12] | ESO 540-2 | 00h 34m 14.0381s | -21° 21' 1.645" | 98.51 Mpc
(321.51 Mly) |
(R')SB(r)b? pec | 1.03 | 15.52 | 7065 | 0.023293 |
| 4C[13] | PGC 2051 | 00h 34m 15.5165s | -21° 25' 03.128" | 267.04 Mpc
(871.56 Mly) |
S0? | 1.51 | 15.90 | 8863 | 0.061409 |
| 4D[14] | PGC 2057 | 00h 34m 16.8280s | -21° 28' 39.880" | 117.07 Mpc
(382.09 Mly) |
E? | 1.19 | 15.68 | 8215 | 0.027492 |
| 4E[15] | PGC 2040 | 00h34m08.3089s | -21° 26' 07.719" | 266.06 Mpc
(868.36 Mly) |
S? | 1.31 | 16.37 | 18480 | 0.061186 |
References
[edit]- ^ "NED results for HCG 4". NASA/IPAC Extragalactic Database. National Aeronautics and Space Administration / Infrared Processing and Analysis Center. Retrieved 2026-07-14.
- ^ Hickson, P. (1982). "Systematic properties of compact groups of galaxies". The Astrophysical Journal. 255: 382. Bibcode:1982ApJ...255..382H. doi:10.1086/159838.
- ^ a b Hickson, P.; Mendes de Oliveira, C.; Huchra, J. P.; Palumbo, G. G. C. (1992). "Dynamical Properties of Compact Groups of Galaxies". The Astrophysical Journal. 399: 353. Bibcode:1992ApJ...399..353H. doi:10.1086/171932.
- ^ Hickson, P. (1993). "Atlas of Compact Groups of Galaxies". Astrophysical Letters and Communications. 29: 1. Bibcode:1993ApL&C..29....1H.
- ^ Verdes-Montenegro, L.; Yun, M. S.; Perea, J.; del Olmo, A.; Ho, P. T. P. (1998-04-10). "Effects of Interaction-Induced Activities in Hickson Compact Groups: CO and Far-Infrared Study". The Astrophysical Journal. 497: 89–107. Bibcode:1998ApJ...497...89V. doi:10.1086/305456.
- ^ a b Mendes de Oliveira, C.; Hickson, P. (1994). "Morphology of Galaxies in Compact Groups". The Astrophysical Journal. 427: 684. Bibcode:1994ApJ...427..684M. doi:10.1086/174176.
- ^ Hickson, P.; Kindl, E.; Auman, J. R. (1989). "A photometric catalog of compact groups of galaxies". The Astrophysical Journal Supplement Series. 70: 687. Bibcode:1989ApJS...70..687H. doi:10.1086/191354.
- ^ a b Kindl, Enrico (1991). A photometric and morphological study of compact groups of galaxies and their environments (Ph.D. thesis). University of British Columbia.
- ^ Mendes de Oliveira, C.; Hickson, P. (1991). "The Luminosity Function of Compact Groups of Galaxies". The Astrophysical Journal. 380: 30. Bibcode:1991ApJ...380...30M. doi:10.1086/170564.
- ^ a b Kindl, E. (1990). A Study of the Environments of Compact Groups of Galaxies (Ph.D. thesis). University of British Columbia. Bibcode:1990PhDT........20K.
- ^ "NED results for HCG 4A". NASA/IPAC Extragalactic Database. National Aeronautics and Space Administration / Infrared Processing and Analysis Center. Retrieved 2026-07-14.
- ^ "NED results for HCG 4B". NASA/IPAC Extragalactic Database. National Aeronautics and Space Administration / Infrared Processing and Analysis Center. Retrieved 2026-07-14.
{{cite web}}: CS1 maint: url-status (link) - ^ "NED results for HCG 4C". NASA/IPAC Extragalactic Database. National Aeronautics and Space Administration / Infrared Processing and Analysis Center. Retrieved 2026-07-14.
{{cite web}}: CS1 maint: url-status (link) - ^ "NED results for HCG 4D". NASA/IPAC Extragalactic Database. National Aeronautics and Space Administration / Infrared Processing and Analysis Center. Retrieved 2026-07-14.
{{cite web}}: CS1 maint: url-status (link) - ^ "NED results for HCG 4E". NASA/IPAC Extragalactic Database. National Aeronautics and Space Administration / Infrared Processing and Analysis Center. Retrieved 2026-07-14.
{{cite web}}: CS1 maint: url-status (link)
