High-resolution observations of SN 1989 M - The interstellar medium in NGC 4579

High-resolution, high S/N spectroscopy of SN 1989M is presented, which allows a detailed study of the interstellar gas in the host galaxy, NGC 4579, a gas-poor spiral near the center of the Virgo Cluster. Four discrete velocity components in Na I and Ca II identified with NGC 4579, with the dominant component at v(h) = 1382 km/s, are identified. It is suggested that this dominant component arises in the H I disk of the galaxy; however, H I observations of NGC 4579 suggest that N (H I) may be as small as 3 x 10 to the 19th/sq cm along the line of sight to the supernova. It is found that the diffuse interstellar bands may be present at a very low level at the redshift of NGC 4579, implying that there is only a small amount of reddening along the line of sight to the supernova. The observed kinematics of the absorption may be typical of lines of sight through the outer parts of the disk of normal, i.e., not gas-poor, spiral galaxies. 21 refs