Accretion Disks Around Young Massive Stars

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" Accretion Disks Around Young Massive Stars"AST- 0098524Massive stars are responsible for many of the basic characteristics of spiral galaxies. They effectively dictate the properties of the interstellar medium through their strong ionizing radiation, vigorous outflowing winds and eventual demise as supernovae explosions. They also influence the formation of subsequent generations of stars by triggering the initial collapse of cloud cores of molecular dust and gas. The dominant mechanism by which high mass stars form remains one of the outstanding problems of stellar astrophysics. Most likely, the mechanism is similar to that which produces low mass stars through the formation and collapse of protostellar disks. But, in the case of massive stars, there must be important modifications to the star forming process brought on by the enormous radiation pressure from the massive protostars. The possibility exists that there is an alternative route for producing stars in the high-mass range but first it is important to look hard for the signatures of disks. Through this award the PI will turn to radio astronomy and exploit the capabilities of the Very Large Array (VLA) and the Very Large Baseline Array to search for and subsequently study disks of this type. The VLA will be used to directly image the dust continuum emission from the accretion disk at a wavelength of 7 mm. The VLBA will be used to identify accretion disks in another way, via the strong water maser line at a wavelength of 1.3 cm and to use this as a kinetic probe. Whether the accretion disks are detected or not, the proposed observations will provide high angular resolution observations of matter in the vicinity of young massive stars.