Astrophys. J., 764, 61 (2013/February-2)
A water maser and NH3 survey of GLIMPSE extended green objects.
CYGANOWSKI C.J., KODA J., ROSOLOWSKY E., TOWERS S., MEYER J.D., EGUSA F., MOMOSE R. and ROBITAILLE T.P.
Abstract (from CDS):
We present the results of a Nobeyama 45 m H2 O maser and NH3survey of all 94 northern GLIMPSE extended green objects (EGOs), a sample of massive young stellar objects (MYSOs) identified based on their extended 4.5 µm emission. We observed the NH3(1,1), (2,2), and (3,3) inversion lines, and detected emission toward 97%, 63%, and 46% of our sample, respectively (median rms ∼ 50 mK). The H2 O maser detection rate is 68% (median rms ∼ 0.11 Jy). The derived H2 O maser and clump-scale gas properties are consistent with the identification of EGOs as young MYSOs. To explore the degree of variation among EGOs, we analyze subsamples defined based on mid-infrared (MIR) properties or maser associations. H2 O masers and warm dense gas, as indicated by emission in the higher-excitation NH3transitions, are most frequently detected toward EGOs also associated with both Class I and II CH3 OH masers. Ninety-five percent (81%) of such EGOs are detected in H2 O (NH3(3,3)), compared to only 33% (7%) of EGOs without either CH3 OH maser type. As populations, EGOs associated with Class I and/or II CH3 OH masers have significantly higher NH3 line widths, column densities, and kinetic temperatures than EGOs undetected in CH3 OH maser surveys. However, we find no evidence for statistically significant differences in H2 O maser properties (such as maser luminosity) among any EGO subsamples. Combining our data with the 1.1 mm continuum Bolocam Galactic Plane Survey, we find no correlation between isotropic H2 O maser luminosity and clump number density. H2O maser luminosity is weakly correlated with clump (gas) temperature and clump mass.
infrared: ISM - ISM: jets and outflows - ISM: molecules - masers - stars: formation
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<Available at CDS (J/ApJ/764/61): table1.dat table3.dat table4.dat table6.dat table8.dat>
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