Proper motions and distances of H2O maser sources. II - W51 MAIN

Abstract

view Abstract Citations (164) References (28) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Proper motions and distances of H2O maser sources. II. W51 MAIN. Genzel, R. ; Downes, D. ; Schneps, M. H. ; Reid, M. J. ; Moran, J. M. ; Kogan, L. R. ; Kostenko, V. I. ; Matveenko, L. I. ; Ronnang, B. Abstract VLBI measurements of relative proper motions of H2O maser features in W51 MAIN are presented, and relative positional accuracies of approximately 100 microarcsec from the analysis of the fringe phases and from the aperture synthesis maps are reported. A detailed description of the observation procedure and the data reduction are given. The observed proper motions are typically 1 milliarcsec/yr, and it is thought that they represent the kinematic motions of maser cloudlets. The transverse motions of most features appear to be random and are interpreted as turbulent motions created when strong stellar wind interacts with density inhomogeneities in the surrounding molecular cloud. The transverse and the radial velocity dispersions are compared, and the distance of W51 is calculated to be 7 + or - 1.5 kpc. Data are also presented on maser spot sizes, and maser cloud physical sizes. A large spread in the brightness temperatures of the maser features is reported, and the line widths of individual maser features are correlated with the local velocity dispersion. Publication: The Astrophysical Journal Pub Date: August 1981 DOI: 10.1086/159113 Bibcode: 1981ApJ...247.1039G Keywords: Interstellar Masers; Molecular Clouds; Radial Velocity; Very Long Base Interferometry; Water Masers; Brightness Temperature; Maser Outputs; Spectral Line Width; Velocity Distribution; Astronomy full text sources ADS | data products SIMBAD (2) Related Materials (1) Part 1: 1981ApJ...244..884G