Spectroscopic evidence for inhomogeneities in the ejecta of the Type Ib supernova 1985F

Abstract

Small-scale irregularities in a moderate-resolution spectrum of the Type Ib supernova 1985F in NGC 4618 are reported. The irregularities are found in the profile of the broad blend of forbidden O I (6300 A and 6364 A) lines, 8.5 months after maximum brightness. The same features 12.5 months after maximum brightness are about 40 percent narrower and about 20 percent stronger. It is suggested that the irregularities are due to the formation of high-density clumps surrounded by regions of lower density. The implications of the observations for the study of SN 1987A are discussed.