CLUMPING AND SMALL-SCALE MIXING IN SUPERNOVA 1987A

We investigate high-resolution line profiles of Halpha, [Fe II] 7155 angstrom and Ca II] 7291,7323 angstrom in the spectra of SN 1987A. We identify a common prominent narrow feature in all four lines. We attribute the emission to a fast knot of metals and hydrogen. Our observations provide the first direct evidence for mixing on a small as well as a large scale in the ejecta of SN 1987A. Our observations support the idea that such knots may well have contributed the bulk of the emission of the supernova after the ejecta cooled and dust formed at about day 500. The ratio of the two components of the blend of Ca II] 7291,7323 angstrom provides an upper limit on the number density of Ca+ of 1 X 10(5) cm-3 on day 673 tor both the knot and the rest of the ejecta.