2000ApJ...542..779H

Ultraviolet imaging of the remnant of supernova (SN) 1885 in M31 with the Hubble Space Telescope using the F255W filter on the WFPC2 reveals a dark spot of Fe II absorption at the remnant's known position in the bulge of M31. The diameter of the absorbing spot, ∼0".5, is consistent with the 0".70±0".05 diameter measured in the higher quality WFPC2 Ca II absorption image previously reported by us. The flux in the spot is 0.76±0.21 lower than that in adjacent regions; that is, three-quarters of the bulge starlight is being absorbed by supernova remnant (SNR) 1885. The depth of absorption is consistent with the amount 0.67±0.04 expected on the basis of a model fit to the previously obtained near-UV Faint Object Spectrograph (FOS) spectrum. The observed depth of Fe II absorption suggests that Fe II is fully saturated, with an iron mass consistent with the range M_Fe=0.1-1.0 M_☉ previously inferred from the near-UV spectrum. Besides Fe, ion species Mg I, Mg II, and Mn I probably make some contribution to the absorption from the SN 1885 remnant in the F255W image.