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Published January 2011 | Published
Journal Article Open

Infall, outflow, and rotation in the G19.61-0.23 hot molecular core

Abstract

Aims. We carried out sub-arcsecond resolution observations towards the high-mass star formation region G19.61−0.23, in both continuum and molecular line emission. While the centimeter continuum images, representing ultra compact HII regions, will be discussed in detail in a forthcoming paper, here we focus on the (sub)mm emission, devoting special attention to the hot molecular core (HMC). Methods. A set of multi wavelength continuum and molecular line emission data between 6 cm and 890 μm were obtained with the Very Large Array, Nobeyama Millimeter Array, Owens Valley Radio Observatory millimeter array, and Submillimeter Array (SMA). These data were analyzed in conjunction with previously published data. Results. Our SMA observations resolve the HMC into three cores whose masses are on the order of 10^1−10^3 M_⊙. No submm core exhibits detectable free-free emission in the centimeter regime, but appear to be associated with masers and thermal line emission from complex organic molecules. Towards the most massive core, SMA1, the CH_3CN (18_K−17_K) lines provide hints of rotation about the axis of a jet/outflow traced by H_2O maser and H^(13)CO^+(1−0) line emission. Inverse P-Cygni profiles of the ^(13)CO (3−2) and C^(18)O (3−2) lines seen towards SMA1 indicate that the central high-mass (proto)star(s) is (are) still gaining mass with an accretion rate ≥3 × 10^(−3) M_⊙ yr^(−1). Owing to the linear scales and high accretion rate, we hypothesize that we are observing an accretion flow towards a star cluster in the making, rather than towards a single massive star.

Additional Information

© 2010 ESO. Received 10 March 2010, Accepted 20 June 2010, Published online 02 December 2010. The authors are grateful to the referee, Dr. S. Curiel, and the editor, Dr. C. M. Walmsley, for their constructive comments to the manuscript. The authors sincerely acknowledge S. Takahashi, M. Momose, L. Testi, and C. Codella for their contribution at early stage of this study as co-authors of Paper I. In particular, S. Takahashi and M. Momose performed the NMA observations and calibrated most of the visibility data. The authors also acknowledge M. J. Claussen and G. V. Moorsel for their extensive help in VLA observations, especially handling the EVLA antenna data, D. Fong for his help in calibrating the SMA data, J. M. Carpenter and J. Lamb for their help in combining the OVRO and NMA visibilities, and A. I. Sargent and P. T. P. Ho for their fruitful comments and encouragement. R.S.F. is supported by a Grant-in-Aid from the Ministry of Education, Culture, Sports, Science and Technology of Japan (No. 20740113).

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