Program: GN-2011A-Q-56

Title:How do massive stars form? NIFS observations of Massive Young Stellar Objects
PI:Stuart Lumsden
Co-I(s): Ben Davies, Melvin Hoare, Rene Oudmaijer, Hugh Wheelwright

Abstract

It is still unknown how a massive protostar with M>10Msun can continue to accrete despite the immense outward radiation pressure exerted on its surroundings. A mechanism which has had success in numerical studies involves accretion from a circumstellar disk, with the radiation pressure driving a bipolar wind. Observational support for this model is limited, but recently we have used Gemini+NIFS observations of a massive forming star to (a) resolve the ionized gas into a fast bipolar wind, (b) show that the envelope is rotationally-flattened in a ?torus?, and is oriented perpendicular to the bipolar wind, (c) find evidence for a circumstellar disk with the same orientation as the torus, and (d) weigh the central star through kinematic analysis of spectral features. Here we propose to expand this study to a sample of objects with a range of masses, providing a critical statistical test for the accretion-disk paradigm of massive star-formation.

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