Optical appearance of the debris of a star disrupted by a massive black hole

We show that the disruption of a star by a similar to 10(6) M. black hole in a galactic nucleus could under favorable circumstances produce an optically thick envelope that radiates with a thermal spectrum at the Eddington limit, similar to 10(44) ergs s(-1), for tens of years. The low apparent temperature of this envelope, similar to 10(4) K, would be easily detectable in optical surveys. If most galaxies harbor a massive black hole at their center, then the Sloan Digital Sky Survey might find hundreds of galaxies with nuclear activity of this type. Because the envelope is driven to shine near the Eddington limit, a measurement of the source redshift and total luminosity could yield the black hole mass.