NGC 3607 - Galaxy Group
In the eastern part of the constellation Leo you can find a great galaxy group, which is even suitable for telescopes of 8" aperture. It consists of
four galaxies in total: NGC 3605/3607/3608 and the very faint PGC 34407, which is located a little aside. The group is about 73 million light years
away from us. The three galaxies in the NGC catalog were all discovered during the same night in 1784 by F.W. Herschel with his 18.7" Newton.
NGC 3607 is the brightest galaxy of the group with an apparent magnitude of 9.9mag and a size of 4.6'x4.0' arcminutes. It has a diameter of 95,000
light-years and a luminosity of 50 billion suns. The classification as "SA0" identifies NGC 3607 as a lenticular galaxy - so it is a mixture of a
spiral galaxy and an elliptical galaxy. The inclination is 34°, that means we are looking at it from obliquely above, making the disk of dust and dust filaments
easily visible. In the center there is a supermassive black hole (SMBH) with a mass of 120 million solar masses. NGC 3607 is surrounded by a halo of
at least 46 globular clusters.
NGC 3608 has an apparent magnitude of 10.8mag and a size of 3.2'x2.6'. It is the second brightest galaxy of this group. With a diameter of 68,000
light-years it is not only much smaller than NGC 3607, but with a luminosity of 20 billion suns it is also fainter. The galaxy is surrounded by a large
number of globular clusters, which can be divided into a red and a blue population. In the center is a black hole with the mass of 460 million suns.
According to the current data, NGC 3607/08 are even interacting with each other and will probably merge at some point in the distant future.
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The three NGC galaxies are of course very bright with 20" aperture and thus easy to see. I remember that the two brightest galaxies were even easy with
8" aperture, but I noticed NGC 3605 only later. With more than twice the aperture NGC 3605 is no longer a problem. This part has now been taken over
by PGC 34407, which I could perceive as a faint glow. If I had not known that it was there, I probably would have missed it.
Since all members of the group are elliptical galaxies, one searches in vain for details. Only a brightness increase towards the center can be seen - sometimes
more and sometimes less pronounced. Worth mentioning is also a small asterism southeast of the galaxy group.
