NGC 4065 Group in Coma Berenices

April 2018 - Galaxy of the Month

This group of 9 NGC galaxies in Coma is an extremely confusing field as some of the galaxies seem to have been observed by William Herschel and then later by John Herschel but given the wrong positions. They were then added into the NGC as separate objects. This has led to a great deal of confusion and to various designation issues.

The main issues seem to surround the galaxies numbered as NGC 4055, NGC 4057 and NGC 4059 discovered by John Herschel. These are probably the same galaxies discovered by his father and catalogued as NGC 4061, NGC 4065 and NGC 4070 respectively.

The situation was then further complicated by Marth who, when observing with Lassell’s 48” in Malta, found two more galaxies in this group. Unfortunately the positions that Marth gave were very uncertain so it is difficult to ascertain which NGC number belongs to which galaxy of those he discovered.

And then there is NGC 4069, another of the galaxies discovered by John Herschel but difficult to tie down to an actual galaxy with any certainty. The situation is further complicated by the fact that the designation NGC 4057 is sometimes given to a completely different galaxy.

The confusion over these galaxy names is amply illustrated by the two finder charts attached, one from Sky Tools that adopts one of the numbering systems and one from Megastar which adopts the other. The mess around the numbering of these objects is discussed in Harold Corwin’s NGC notes.

NED appears to adopt the primacy of the NGC 4065 system. If we adopt that numbering system then the NGC 4065/4061 pair is also an interacting pair numbered VV 179. Most of the galaxies in the group are ellipticals with the exception of NGC 4072 which is a spiral.

The whole group is listed in the WBL catalogue of poor galaxy clusters as WBL 374 which is listed as containing 19 galaxies, including the NGC galaxies 4061, 4060, 4065, 4066, 4070, 4072, 4076, 4074, 4086, 4090, 4089, 4091, 4092, 4093, 4095 and 4098. If this is correct the group would contain two sub groups centred around the galaxies NGC 4057 and NGC 4095, separated by perhaps 30’. Unfortunately the designation issues in the second sub group around NGC 4095 are just as messy as in the first.

NGC 4098 would also appear to be an interacting system and is catalogued as VV 61. It would be interesting to know what power and size of telescope is required to split this system as the SDSS image shows a second galaxy much closer in along with the disturbed spiral arms of the main galaxy. As the separation between the galaxies is only about 10” it is likely to require high power and good seeing.

The distance to this group is probably of the order of 100 Mpc. The magnitudes of these galaxies suggest that to adequately explore the group, certainly from typical UK skies, will require a telescope of at least 40cm aperture and probably more.

Andrew Robertson when using his 24” telescope drew not only the NGC galaxies in the 4057 subgroup but also managed to pick up one of the UGC ones as well. Unfortunately at the time he did not know about the rest of the group so was not able to get the others.

Owen Brazell - Galaxy Section Director