NGC 4278 in Coma Berenices
May 2025 - Galaxy of the Month
As the brightening skies of May approach, I have chosen for the galaxy of the month the trio of galaxies in Coma Berenices, NGC 4278, NGC 4283 and NGC 4286. All three of these galaxies were discovered by William Herschel in 1785.
NGC 4278 is the brightest of the trio and is an elliptical galaxy classified as E1-2. It contains an AGN of the LINER type. A small pair of weak radio jets have been found in the galaxy as well as it having a strong and variable UV source at its centre. This flaring variability also extends to the X-Ray output from the galaxy. The radio jets also appear to be associated with high energy gamma ray emission from the galaxy. Images with the Hubble space telescope also show a lot of dust features near the nucleus which is unusual for an elliptical galaxy. The galaxy is also surrounded by a larger number of globular clusters than expected. NGC 4278 is thought to be about 55 million light-years away.
NGC 4283 is also an elliptical galaxy classified as E0. NGC 4286 is probably a lenticular galaxy, but has also been classified as a dwarf galaxy, and it does show a lot of emission in the UV which suggests a lot of star formation going on.
In fact, given the distance all the galaxies here are quite small with the largest, NGC 4278, probably only about 65,000 light-years across, so about half the size of our Milky Way. The group are probably physically associated and have the designation 399 in the WBL catalogue. The group are suspected to be part of one of the filaments associated with Virgo cluster.
It is also suggested that NGC 4278 is part of a galaxy group associated with NGC 4274, although there is some debate on that. It is also part of the Coma I group of the Virgo cluster. NGC 4274 lies about 20’ to the north of NGC 4278.
NGC 4278 is a part of the Astronomical League's H400 list and at around 11th magnitude should be visible in quite small telescopes. NGC 4283 is much fainter at around 13th magnitude so should be more of a challenge for larger telescopes. NGC 4286 is fainter still at around 14th magnitude so will require a much larger telescope to find unless you have access to very dark skies.
It does help that the brighter two galaxies are ellipticals with bright cores so should be easy to spot. NGC 4286 is an edge on galaxy so it will be harder to see. The group is however quite tight and will fit in the same field of view using a modern hyperwide field eyepiece at high power, which may be the best way to catch NGC 4286. The Night Sky Observer's Guide Vol 2 suggests that in a 35cm telescope NGC 4286 is a difficult faint smudge. The other two should be visible in 25cm telescopes. The galaxy also makes The Cambridge Photographic Atlas of Galaxies.
Owen Brazell - Galaxy Section Director
If you'd like to try out the Clear Skies Observing Guides (CSOG), you can download observing guide for the current Galaxy of the Month without the need to register. CSOG are not associated with the Webb Deep-Sky Society but the work of Victor van Wulfen.
