IC 342/Maffei Group
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| Galaxy groups and clusters |
List of galaxy groups and clusters |
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| Observation data (Epoch J2000) |
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| Constellation(s): | Cassiopeia/Camelopardalis/Perseus |
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| Declination | |
| Number of galaxies: | ~21 |
| Brightest member: | |
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The IC 342/Maffei Group (also known as the IC 342 Group or the Maffei 1 Group) is the nearest group of galaxies to the Local Group. Its brightest member is the spiral galaxy IC 342. Two of the other galaxies in the group, Maffei 1 and Maffei 2 were discovered on infrared plates in 1968 by the Italian astronomer Paolo Maffei (1926-). Both galaxies lie near the galactic equator in Cassiopeia in the Zone of avoidance and are thus heavily obscured at visible wavelengths by dust and gas. Maffei 2 is a medium-sized, average-brightness barred spiral galaxy about 16 million light-years away, while the distance to Maffei 1 has been put at around 10 million light-years. Other known galaxies in the group are Dwingeloo 1 and its satellite galaxy Dwingeloo 2, and some smaller systems, including two possible satellites of Maffei 1 (MB1 and MB2). The group is one of many located within the Virgo Supercluster (i.e. the Local Supercluster).[1]
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[edit] Members
| Name | Type | Distance from sun[2] (million ly) |
Magnitude | Member? | Comments |
|---|---|---|---|---|---|
| IC 342 | SBcd | 10.7 | +10.5 | Yes | |
| Maffei 1 | E5 | 9.82 | +17 | Yes | |
| Maffei 2 | SBc | 9.1 | +16 | Yes | |
| Dwingeloo 1 | SBbc | 9.1 | Yes | PGC 100170, Cassiopeia 2 | |
| Dwingeloo 2 | dIAm | ~10 | +20.5 | Yes | PGC 101304 |
| NGC 1560 | SAd | 11.3 | +12.1 | Probably | Possible member of the Local Group |
| NGC 1569 | dIBm | +11.8 | Probably | Possible member of the Local Group | |
| UGCA 92 | dIAm | +16.15 | Probably | Possible member of the Local Group | |
| Camelopardalis A | dSph | 12.8 | Probably | ||
| Camelopardalis B | IAm | 10.9 | Possibly | KK 44 | |
| Camelopardalis D | IAm | Possibly | KKH 34 | ||
| Cassiopeia 1 | ~11 | Possibly | KK 19 | ||
| Cassiopeia 3 | Possibly | KKH 5 | |||
| KK 35 | 10.3 | Possibly | |||
| MB1 | SAd? | ~10 | Possibly | KK 21 | |
| MB2 | Possibly | ||||
| MB3 | dSph | ~10 | Possibly | KK 22 | |
| Perseus 1 | E | +12.48 | Possibly | KKH 11 | |
| Perseus 2 | IAm | Possibly | KKH 12 | ||
| UGCA 86 | dIAm | 10.2 | +14.2 | Possibly | Possible member of the Local Group |
| UGCA 105 | dIAm | 10.3 | +15.3 | Possibly | |
| KKH 6 | Possibly | ||||
| UGC 2773 | Possibly | KK 28 | |||
| Mailyan 16 | Possibly | KKH 37 |
[edit] Group formation and possible interactions with the Local Group
Since the IC 342/Maffei Group and the Local Group are located physically close to each other, the two groups may have influenced each other's evolution during the early stages of galaxy formation. An analysis of the velocities and distances to the IC 342/Maffei Group as measured by M. J. Valtonen and collaborators suggested that IC 342 and Maffei 1 were moving faster than what could be accounted for in the expansion of the universe. They therefore suggested that IC 342 and Maffei 1 were ejected from the Local Group after a violent gravitational interaction with the Andromeda Galaxy during the early stages of the formation of the two groups.[3] However, this interpretation is dependent on the distances measured to the galaxies in the group, which in turn is dependent on accurately measuring the degree to which interstellar dust in the Milky Way obscures the group. More recent observations have demonstrated that the dust obscuration may have been previously overestimated, so the distances may have been underestimated. If these new distance measurements are correct, then the galaxies in the IC 342/Maffei Group appear to be moving at the rate expected from the expansion of the universe, and the scenario of a collision between the IC 342/Maffei Group and the Local Group would be implausible.[4]
[edit] External links
[edit] References
- ^ R. B. Tully (1982). "The Local Supercluster". Astrophysical Journal 257: 389-422.
- ^ Karachentsev, I. D. (2005). "The Local Group and Other Neighboring Galaxy Groups". The Astronomical Journal 129: 178. arXiv:astro-ph/0410065.
- ^ M. J. Valtonen, G. G. Byrd, M. L. McCall, K. A. Innanen (1993). "A revised history of the Local Group and a generalized method of timing". Astronomical Journal 105: 886-893.
- ^ R. L. Fingerhut, H. Lee, M. L. McCall, M. G. Richer (2006). "The Extinction and Distance of Maffei 2 and a New View of the IC 342/Maffei Group". Astrophysical Journal (in press). arXiv:astro-ph/0610044
