NGC 4298 in Coma Berenices
April 2022 - Galaxy of the Month
Our galaxy of the month this month is the nice galaxy pair in Coma, NGC 4298 and NGC 4302, both of whom were discovered by William Herschel in 1784. They are both spiral galaxies with NGC 4298 being almost face on and NGC 4302 being edge on.
Although they lie in the constellation of Coma they are actually part of the Virgo cluster lying at a distance of perhaps 55 million light-years away. At this distance the core-to-core distance between the pair is thought to be only about 35000 light-years but they don’t seem to be showing any signs of interaction, at least in the visual part of the spectrum. There is, however, a tidal bridge that was discovered in the radio spectrum using the line of neutral hydrogen (HI).
NGC 4302 is also suspected to be a Seyfert or LINER type galaxy with an AGN. NGC 4302 also sports a tidal tail that is likely due to the RAM pressure from the intracluster gas as it falls into the Virgo cluster. The boxy nature of the nucleus of NGC 4302 also suggests that it may have a bar, however this would not fit with its Sc classification (it would be SBc in that case).
NGC 4298 shows numerous star forming regions in ultraviolet images taken with the GALEX satellite. Its classification is SA(rs)c, although it is also classified as a flocculent spiral.
There is a glorious image of the pair taken as part of the 27th anniversary of the launch of Hubble. Here NGC 4302 looks a little like the brighter NGC 891. NGC 4302 does show a single very bright blue star forming region that is very prominent in the UV images. There may be others that are hidden behind its dust lane. They are both somewhat smaller than our Milky Way galaxy. The pair is also known as Holmberg 377.
The two galaxies are so close together that they will fit in a high power field of view and this maybe the best way to look at them.
NGC 4298 and NGC 4302 both make it into Night Sky Observer's Guide (NSOG) Vol. 2 where it suggests they are targets for 20-25cm telescopes. I suspect this may not be the case if you live in the UK. NGC 4298 and 4302 both make it into the Herschel II observing list from the Astronomical League. The pair also made the DeepSkyForum.com Object of the Week (OOTW) in 2015. It seems that to see the dust lane in NGC 4302 requires a very large telescope from those reports. The pair are listed, although not described, in Burnham's Celestial Handbook and makes multiple Texas Star Party (TSP) observing lists.
If you find this pair too easy then try for the 15th magnitude galaxy MCG 3-32-12 nearby, it should fit in the same medium power field as the main pair.
Owen Brazell - Galaxy Section Director