Messier 77, Cetus A + NGC 1055
History
The galaxy M 77 was discovered by Pierre Méchain on October 29, 1780. Charles Messier verified the observation on December 17, 1780 and wrote: «A cluster of small stars with nebulae, in the whale on the parallels of the star δ [Ceti], third magnitude, which M. Messier estimated only to be fifth. M. Méchain saw the cluster on October 29, 1780 in the form of a mist.» [281] Wilhelm Herschel also saw a «poorly defined star surrounded by nebula» in his 7 feet focal length telescope in 1783. In his large 10 feet telescope he saw «a kind of greatly enlarged star cluster with a few bright stars in the middle». Only Lord Rosse recognized the spiral nature of this galaxy in 1850. [217] Halton Arp included the galaxy M 77 in his «Atlas of Peculiar Galaxies» published in 1966 as Arp 37, since he suspected small companion galaxies in the bright nodes. A few smaller, much more distant galaxies can also be seen at the edge of M 77. [199]
Physical Properties
At a distance of about 44 million light years, M 77 is the closest and brightest Seyfert galaxy, a group of galaxies with a very active core, lots of hot, ionized, brightly shining gas and a high rate of star formation. In the core there is a supermassive black hole of about 15 million solar masses, which is also a strong source of X-rays and radio radiation. Hence the name «Cetus A». [215]
Only half a degree away is the galaxy NGC 1055, which we can see directly from the side. This was discovered by Wilhelm Herschel on December 18, 1783. The distance is estimated to be about 45 to 50 million light years and the diameter to about 115'000 light years. It belongs to the same group as M 77. It could also be a starburst galaxy similar to M 82. [196]
The small, faint galaxy NGC 1072 is much further away with 114 Mpc (approx. 372 million light years) and does not belong to the group. The best observation time is September to December.
Finder Chart
The galaxy group is located in the constellation Cetus (Whale), less than 1 ° from δ Ceti.
