M77 September 07, 2008 at UT 10:38


Spiral Galaxy M77 (NGC 1068), type Sbp, in Cetus 

This magnificient galaxy is one of the biggest galaxies in Messier's catalog, its bright part measuring about 120,000 light years, but its faint extensions extend out to nearly 170,000 light years. Its appearance is that of a magnificient spiral with broad structured arms, which in the inner region show a quite young stellar population, but more away from the center, are dominated by a smooth yellowish older stellar population. 

M77 is about 60 million light years distant, approximately the same distance but another direction as the Virgo cluster, and is receding from us at about 1100 km/sec, as was first measured by Slipher of Lowell Observatory in 1914; it was the second galaxy with a large measured redshift after the Sombrero galaxy, M104 (Tully's Nearby Galaxies Catalog gives a somewhat smaller value for the distance, 47 million light years). 

This galaxy is unique and peculiar for several reasons. First, its spectrum shows peculiar features in the form of broad emission lines, indicating that giant gas clouds are rapidly moving out of this galaxy's core, at several 100 km/sec. This feature classifies M77 as a Seyfert galaxy of type II; it is the nearest and brightest representative of this class of active galaxies. An enormous energy source is required to generate this velocity, which must sit in the galaxy's core. This core has been found to be a strong radio source. 

It was Donald E. Osterbrook and R.A.R. Parker in 1965 who brought up the hypothesis that Seyfert galaxies might be thought of as miniature quasars (quasi-stellar radio sources), according to Burnham. 

M77 is the dominating member of a small physical group of galaxies, which includes NGCs 1055 (type Sb) and 1073 (type SABc), as well as UGCs 2161 (DDO 27, type Im), 2275 (DDO 28, type Sm - designating a morphiological type between spirals and irregulars) and 2302 (DDO 29, type Sm), and the irregular galaxy UGCA 44 and the SBc barred spiral Markarian 600. NGCs 1087(Sc), 1090 (S-), and 1094 (SABb-) are nearby background galaxies, as their much higher redshift indicates (Info from Burnham, Tully, and the Sky Catalogue 2000). 

Right ascension 02 : 40.1 (hours : minutes)
Declination +00 : 14 (degrees : minutes)
Distance 47000.0 (light-years*10^3)
Visual magnitude 8.9

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