A study of the interstellar medium in line to M83 from high-resolution observations of the nucleus and supernova 1983n

Abstract

In the last few years, technological advances have made supernovae in nearby galaxies (within approximately 10-20 Mpc) accessible to interstellar observations. The present paper is concerned with observations of a supernova, which has been discovered on July 3, 1983 in the bright spiral galaxy NGC 5236 (M83). The observations reported were made between July 14, and 17, 1983 with the new echelle spectrograph at the Cassegrain focus of the 3.6 m telescope at the European Southern Observatory. It is pointed out that the signal-to-noise ratio achieved in these observations is significantly better than the corresponding value in some other investigations. For this reason, a more precise analysis of the complex absorption line profiles is possible. Attention is given to observations and data reduction, the interstellar sepctrum of supernova 1983n, the spectrum of the nucleus of M83, Milky Way absorption, questions regarding the presence of metal-enriched intergalactic gas, and absorption at M83 velocities.