NGC 4395 is a low surface brightness spiral
galaxy with a halo that is about 8′ in diameter. It has several
wide areas of greater brightness running northwest to southeast.
The one furthest southeast is the brightest. Three of the
patches have their own NGC numbers: 4401, 4400, and 4399 running
east to west. NGC 4395 is notable in that it contains one of the
smallest supermassive black hole ever discovered. The central
black hole has a mass of "only" 300,000 sun masses. The black
hole was discovered in 1989, and had been judged to be between
55,000 and 65,000 sun masses. Recent estimates have thus
quintupled the estimated size, but it is still far smaller than
other black holes in its class. It is likely that is it so small
because it has little material around it to add to its bulk.
Indeed, stars are conspicuously absent in its immediate
vicinity, and so it was "starved" down to that size or has never
been able to fully grow, unlike most similar black holes.
