VLBI aperture synthesis observations of H2O masers associated with molecular clouds.
Abstract
A system of programs for aperture synthesis mapping of spectral line VLBI data has been developed and applied to data from a five-station experiment. The interferometer phase is derived from the phase of a modeled reference feature. Synthesis maps of the H2O maser emission in W51, ON 2, and CRL 2591 are presented. Fringe rate maps are presented of W3 (OH) and W3(C) H2O for which synthesis maps could not be made. The maps are used to identify characteristic scale sizes in H2O sources and to discuss the state of saturation, the density, and the minimum size of masers. Pairs of knots with emission over a wide velocity range, which are seen in the maps of W51 and CRL 2591, are discussed in terms of collapsing-cloud and thin-shell models. A model for H2O maser sources involving dust shells around newly formed, massive stars is used to explain the general features of the maps.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- November 1978
- DOI:
- 10.1086/156589
- Bibcode:
- 1978ApJ...226...95W
- Keywords:
-
- Interstellar Masers;
- Radio Astronomy;
- Very Long Base Interferometry;
- Water Masers;
- Apertures;
- Astronomical Maps;
- Astronomical Models;
- Cosmic Dust;
- Interstellar Gas;
- Line Spectra;
- Power Spectra;
- Stellar Evolution;
- Astrophysics;
- Molecular Clouds:Water Masers;
- VLB Interferometry:Water Masers