The molecular environment of water masers: VLA ammonia observations


C. Codella, (1) L. Testi (2), R. Cesaroni (3)

(1) Max Plank Institut fuer Radioastronomie, Auf dem Huegel 69, D-53121 Bonn, Germany

(2) Dipartimento di Astronomia e Scienza dello Spazio, Universitá di Firenze, Largo E. Fermi, 5, I-50125 Firenze, Italy

(3) Osservatorio Astrofisico di Arcetri, Largo Enrico Fermi 5, I-50125 Firenze, Italy


We present the results of single dish and interferometric observations in the (2,2) and (3,3) inversion transitions of ammonia towards 5 sources selected from a sample of H2O and OH masers associated with star forming regions. The 1.3 cm continuum was also observed with the interferometer. The main goal of this research is to confirm the belief that H2O masers form in hot dense molecular cores which are sites of massive star formation. We also find evidence for the H2O maser phase to be prior to the appearance of an ultracompact HII region around the embedded high mass star(s).

Mantained by: Leonardo Testi