A study of the H I absorption in the galaxy M82 by radio interferometry.
Abstract
The continuum source located in the Irr II galaxy M82 has been studied in H I absorption at 21-cm wavelength. Absorption by gas located in M82 has been detected and mapped with an east-west interferometer. The maximum baseline length was approximately 4300 A. The velocity resolution was 21 km i The positions of 13 velocity centroids of the H I absorption have been determined to within 1"-3" accuracy relative to one another. This allows direct comparison with Heckathorn's recent optical study. For the first time close agreement is found between the systemic velocities of M82 determined by optical and radio methods. While Heckathorn finds a velocity of 243 + 3 km s ', the present study yields 240 + 10km -1 The variation of the H I radial velocity across the central region is much more consistent with optical emission lines than with optical absorption lines. Several features of the velocity field are then discussed particularly in the framework of the dustscattering models recently proposed by Sanders and Balamore for M82. Subject headings: galaxies, individual - galaxies, motions in - radio sources - 21-cm radiation
- Publication:
-
The Astrophysical Journal
- Pub Date:
- August 1974
- DOI:
- 10.1086/153004
- Bibcode:
- 1974ApJ...191..639W