title: A hot compact dust disk around a massive young stellar object.
abstract: Circumstellar disks are an essential ingredient of the formation of low-mass stars. It is unclear, however, whether the accretion-disk paradigm can also account for the formation of stars more massive than about 10 solar masses, in which strong radiation pressure might halt mass infall. Massive stars may form by stellar merging, although more recent theoretical investigations suggest that the radiative-pressure limit may be overcome by considering more complex, non-spherical infall geometries. Clear observational evidence, such as the detection of compact dusty disks around massive young stellar objects, is needed to identify unambiguously the formation mode of the most massive stars. Here we report near-infrared interferometric observations that spatially resolve the astronomical-unit-scale distribution of hot material around a high-mass ( approximately 20 solar masses) young stellar object. The image shows an elongated structure with a size of approximately 13 x 19 astronomical units, consistent with a disk seen at an inclination angle of approximately 45 degrees . Using geometric and detailed physical models, we found a radial temperature gradient in the disk, with a dust-free region less than 9.5 astronomical units from the star, qualitatively and quantitatively similar to the disks observed in low-mass star formation. Perpendicular to the disk plane we observed a molecular outflow and two bow shocks, indicating that a bipolar outflow emanates from the inner regions of the system.
authors.affiliation: Department of Astronomy, University of Michigan, 500 Church Street, Ann Arbor, Michigan 48103, USA. stefankr@umich.edu
authors.forename: Stefan
authors.initials: S
authors.lastname: Kraus
authors.forename: Karl-Heinz
authors.initials: KH
authors.lastname: Hofmann
authors.forename: Karl M
authors.initials: KM
authors.lastname: Menten
authors.forename: Dieter
authors.initials: D
authors.lastname: Schertl
authors.forename: Gerd
authors.initials: G
authors.lastname: Weigelt
authors.forename: Friedrich
authors.initials: F
authors.lastname: Wyrowski
authors.forename: Anthony
authors.initials: A
authors.lastname: Meilland
authors.forename: Karine
authors.initials: K
authors.lastname: Perraut
authors.forename: Romain
authors.initials: R
authors.lastname: Petrov
authors.forename: Sylvie
authors.initials: S
authors.lastname: Robbe-Dubois
authors.forename: Peter
authors.initials: P
authors.lastname: Schilke
authors.forename: Leonardo
authors.initials: L
authors.lastname: Testi