A New Sample of Massive Young Stellar Object Outflow Candidates: Extended Green Objects (EGOs) from the GLIMPSE Survey

Type Conference Paper
Names Claudia Cyganowski, C. Brogan, T. Hunter, E. Churchwell
Proceedings Title Bulletin of the American Astronomical Society
Conference Name American Astronomical Society, AAS Meeting #215, #345.04
Volume 42
Pages 451
Date January 1, 2010
Short Title A New Sample of Massive Young Stellar Object Outflow Candidates
URL http://adsabs.harvard.edu/abs/2010AAS...21534504C
Library Catalog NASA ADS
Abstract A promising new diagnostic for identifying actively accreting massive young stellar objects (MYSOs) has emerged from large-scale Spitzer surveys of the Galactic plane: extended emission in the IRAC 4.5 micron band, believed to trace shocked molecular gas in active protostellar outflows. I will discuss the GLIMPSE catalog of extended 4.5 micron sources (called EGOs, Extended Green Objects, for the common coding of the [4.5] band as green in 3-color composite IRAC images) and the evidence that EGOs, as a population, are massive YSOs. I will present the results of high-resolution EVLA surveys of 20 EGOS in the 6.7 GHz Class II and 44 GHz Class I methanol maser transitions, which respectively trace high-mass protostars and molecular outflows, and a JCMT survey in the molecular outflow tracers HCO+ and SiO. High detection rates of all outflow tracers and the spatial distribution of the masers with respect to the midinfrared emission provide convincing evidence that the surveyed EGOs are much-sought MYSOs which are actively accreting and driving outflows. I complement the survey results with detailed case studies of two EGOs using SMA and CARMA data. The high-resolution mm observations reveal bipolar molecular outflows coincident with the 4.5 micron lobes in both sources. Strong SiO(2-1) emission is also detected, confirming that the extended 4.5 micron emission traces recently shocked gas in active outflows. While a single dominant outflow is identified in each of the studied EGOs, the mm data show that one of the EGOs is associated with at least three compact cores, and may be a protocluster. Support for this work was provided by NSF grant AST-0808119, by a NRAO Graduate Summer Student Research Assistantship to C. Cyganowski, and by a NSF Graduate Research Fellowship to C. Cyganowski.
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