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

Observations of Masers in Regions of Star Formation

“…The main new results are (i) a proper H 2 0 aperture synthesis of the intense, low velocity "double knot" at the core of the source , which results provide spectra across the source at inter vals of 1 mi 11i arc sec, and (ii) a series of VLBI maps of the structure of the entire source made by Genzel et al (1979b). A map from the latter study is shown in Fig.…”

“…The H 2 0 masers in W51 have been the object of several recent VLBI investigations , Mader et al 1978, 1979b). …”

The Interpretation of High Velocity H2O Masers

“…https://doi.org/10.1017/S0074180900073344 Downloaded from https://www.cambridge.org/core. IP address: 18.236.120.13, on 13 May 2018 at 08:20:52, subject to the Cambridge Core terms of use, limitation connected to the fact that the HVF produced in such a way must be generated in the same spatial region as the low velocity maser features, a requirement that again contradicts the observations (Genzel et al 1978). Burdyuzha (1978), Fernandez and Reinisch (1978), and Burdyuzha et al (1979) suggest that HVF are the Langmuir satellites of maser radiation at frequencies u)o±^e (U)Q 1S tne cyclic frequency of the maser radiation, oo e is the plasma frequency).…”

“…Therefore the HVF are an interesting phenomenon in the physics of galactic masers. The latest VLBI obser vations (Genzel et al 1978(Genzel et al , 1979 have discovered new peculiarities of the spatial distributions of the maser features, namely their grouping around centers of activity. The low velocity (±15 km s _1 ) most intense maser features form the centers of activity.…”

“…High velocity H 2 0 maser features cluster around the centers of activity at both positive and negative velocities, occupying a large spatial area. The HVF vary in time (Morris 1976, Gammon 1976, Little et al 1977, White 1979, Genzel et al 1979.…”