NGC 4395 has a halo that is about 8′ in diameter. It has several patches 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.[5]
The galaxy is highly unusual for Seyfert galaxies, because it does not have abulge and is considered to be adwarf galaxy.[4]
NGC 4395 was imaged and classified as a "spiral nebula" in a 1920 paper byastronomerFrancis G. Pease.[6] Now, it is known to be a galaxy distinct from theMilky Way (seeGreat Debate). Along with several other nearby galaxies, resolved stars in NGC 4395 were used to measure theexpansion rate of the Universe byAllan Sandage andGustav Andreas Tammann in their 1974 paper.[7] More recently, NGC 4395 was discovered to contain a very low-luminosity active galactic nucleus.[8] Since then, its nucleus has been the subject of several academic papers and attempts to measure the mass of its central black hole.
NGC 4395 is one of the least luminous and nearest Seyfert galaxies known.[4] The nucleus of NGC 4395 is notable for containing one of the smallestsupermassive black holes with a well-measured mass.[9] The central black hole has a mass of "only" 300,000M☉.[10] However, more recent studies found a black hole mass of just 4,000M☉ to 20,000M☉.[11][12][13] The low-mass black hole in NGC 4395 would make it a so-called "intermediate-mass black hole".[14] The black hole may have a truncated disk.[15]
^Sandage, A.; Tammann, G. A. (December 1974). "Steps toward the Hubble constant. IV - Distances to 39 galaxies in the general field leading to a calibration of the galaxy luminosity classes and a first hint of the value of H sub 0".The Astrophysical Journal.194: 559.Bibcode:1974ApJ...194..559S.doi:10.1086/153275.ISSN0004-637X.
^Garcia, A. M. (1993). "General study of group membership. II. Determination of nearby groups".Astronomy and Astrophysics Supplement Series.100: 47.Bibcode:1993A&AS..100...47G.
