Discovery of an Extremely Low Luminosity Seyfert 1 Nucleus in the Dwarf Galaxy NGC 4395

We have discovered a Seyfert 1 nucleus in the center of the nearby (d ~ 2.6 Mpc), late-type (Sd III-IV), dwarf galaxy NGC 4395. Such nuclei have never been seen in galaxies of this kind. The optical spectrum reveals very strong, narrow emission lines covering a wide range of ionization from [O I] to [Fe X]. Weak wings having FWZI ~ 4000-8000 km s^-1^ are visible in the permitted-line profiles, including He II λ4686. H II regions in the rest of the galaxy have normal spectra. The luminosity of the broad Hα emission is ~ 1.2 x 10^38^ ergs s^-1^, a factor of 10 fainter than in the nucleus of M81; thus, NGC 4395 contains the least luminous known Seyfert 1 nucleus. The equivalent width of broad Hα (270 A) is similar to that in normal, luminous Seyfert 1 galaxies. The optical continuum is featureless, and has M_B_ ~ 9.8 mag--less luminous than the brightest known supergiant stars. It is possible that the nuclear properties of NGC 4395 can be explained in terms of stellar phenomena, rather than by accretion onto a black hole.