WILSON, Thomas L.; CLARKE, T. E.; BOBOLTZ, D. A.; HENKEL, C.; MAUERSBERGER, R.; WOOTTEN, H. A.; BROUILLET, N.; BAUDRY, Alain; DESPOIS, D.

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WILSON, Thomas L.

CLARKE, T. E.

BOBOLTZ, D. A.
U.S. Naval Observatory

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Communication dans un congrès

Ce document a été publié dans

American Astronomical Society, AAS Meeting #223, #331.03 - 5-9 January 2014 in Washington, DC, 2014, Washington, DC.

Résumé en anglais

The galactic continuum sources W51D and W51e1e2 have been long recognized as remarkable centers of ammonia maser phenomena in the centimeter wavelength range. Henkel et al. (2013 A&A 549, A90) have measured 19 masers, of which 13 are newly found for W51-IRS2, otherwise known as W51D. These arise from inversion-rotation transitions. The single dish data were taken with the Effelsberg 100-m radio telescope of the MPIfR with an angular resolution of 43 arc seconds. The conclusion that these lines were caused by maser action is based on: (1) time variability, and (2) narrow linewidths. In addition, some lines showed systematic velocity variations. High brightness temperatures and compact sizes are needed to conclusively prove maser action. We have measured a sub-set of these ammonia lines with the C array of the Jansky-Very Large Array of the National Radio Astronomy Observatory in June 2013 with an angular resolution of better than 1 arc second. Source sizes, positions, excitation models and reasons why W51 shows such a plethora of masers will be presented.< Réduire

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Laboratoire d'Astrophysique de Bordeaux (LAB) - UMR 5804