Accession Number : AD0727578

Title :   Aperture Synthesis Study of Neutral Hydrogen in the Galaxy M 101. I. Observations. II. Discussion,

Corporate Author : OWENS VALLEY RADIO OBSERVATORY PASADENA CALIF

Personal Author(s) : Rogstad,D. H. ; Shostak,G. S.

Report Date : 1971

Pagination or Media Count : 50

Abstract : Synthesis observations of neutral hydrogen emission in the spiral galaxy M101 obtained with the Owens Valley twin-element interferometer are presented. The spatial resolution is 4 sec. of arc, and the velocity resolution is 21 km/s. The observations are given in the form of contour maps of the integral and the mean velocity of the HI profile at each position in the galaxy, and a line profile for the galaxy as a whole. A contour map of the 21 cm continuum radiation is also presented. The observations described in another paper (Rogstad and Shostak, 1971) are discussed with the following conclusions: There is a close correspondence between features in the surface density of both light and HI in the galaxy M101. The HI velocity field contains streaming motions which are in agreement with the predictions of the first-order density wave theory of spiral structure. There is evidence for expansion motions of at least 40 km/s in the central region of the galaxy. (Author)

Descriptors :   (*INTERSTELLAR MATTER, HYDROGEN), (*EXTRATERRESTRIAL RADIO WAVES, GALAXIES), RADIO INTERFEROMETERS, FOURIER ANALYSIS, MAPS

Subject Categories : Astrophysics

Distribution Statement : APPROVED FOR PUBLIC RELEASE