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RadioAstron observations of the H2O maser emission in the star forming region W49N

Submitter: Nadya Shakhvorostova
Description: Water vapor masers are commonly used as an important tool for the study of the star formation process as well as scattering in the interstellar medium. Water vapor masers usually have compact structure and high flux density, and can be visible on large distances both in our Galaxy and in other galaxies.

Extremely high angular resolution is needed for investigation of their angular structure. Linear sizes of Galactic H2O masers are about 1-100 AU and, thus, they are unresolved in milli-arcsec angular resolution or finer. Space-VLBI mission RadioAstron provided highest angular resolution as fine as 7 μas and permitted size estimates of the most compact structures in star forming regions.

I will discuss the results of our RadioAstron observations of H2O maser emission associated with the massive star formation region W49N. There were five observing sessions in the RadioAstron maser survey program during 2014-2015. Fringes on space-ground baselines were detected with angular resolution as fine as 23 μas, which corresponds to a baseline of 9.6 Earth diameters. We have measured smooth, nearly continuous, visibility functions from 100 to 5000 Mλ for several spectral features in W49N.

In my talk I will give our current interpretation of these results.
Copyright: Image credit: Nadya Shakhvorostova / RadioAstron
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