Variability of the spectrum and spatial structure of the H2O maser in W75N-VLA 1

• Published in: Astronomy reports Vol. 53; no. 5; pp. 420 - 427
• Main Authors: Lekht, E. E., Slysh, V. I., Krasnov, V. V.
• Format: Journal Article
• Language: English
• Published: Dordrecht SP MAIK Nauka/Interperiodica 01-05-2009; Springer Nature B.V
• Subjects: Astronomy; Astrophysics; Observations and Techniques; Physics; Physics and Astronomy; Radio astronomy; Radio telescopes; Studies; 97.10.Fy; 95.85.Bh
• ISSN: 1063-7729; 1562-6881
• DOI: 10.1134/S1063772909050059

A model of the source associated with VLA 1 in W75N is constructed based on monitoring of the H
2
O maser carried out on the 22-m radio telescope of the Pushchino Radio Astronomy Observatory and NRAO VLA maps of the source at epochs 1992, 1996, 1998, and 1999. The source has a complex hierarchical structure. Individual maser spots form compact clusters in the form of filaments or chains, as well as more extended arc-like clusters. There are radial-velocity gradients in the chains and filaments. All these structures are arranged in a very elongated disk. This complex configuration could arise due to various-scale turbulent motions of the emitting material, from microturbulence to large-scale turbulence. The strong elongation could be due to an outflow of material from the star. No radial motions of individual clusters of spots with respect to the central source in VLA 1 have been found. The presence of these spots at various epochs could be due to the passage of MHD waves, which excite the maser emission in corresponding zones of the maser source. This process could have a cyclic character, and be associated with the flare activity of the central star.