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Photoevaporation of Disks Around Young Stars: Application to Ultracompact HII Regions, Proplyds, and the Solar NebulaYoung massive stars produce sufficient Lyman continuum photon luminosity to significantly affect the structure and evolution of the accretion disks surrounding them. A nearly static, ionized, isothermal 10' K atmosphere forms above the neutral disk, creating a photoevaporative flow from the outer parts of the disk. The resulting slow (10-50 km/s) ionized outflow, which persists for greater than or approximately 10(exp 5) years for disk masses M(sub d) to approximately 0.3M(sub *), may explain the observational characteristics of many ultracompact HII regions. We compare model results to the observed radio free-free spectra and luminosities of ultracompact HII regions and to the interesting source MWC349, which is observed to produce hydrogen masers. We also apply the results to the early solar nebula to explain the the dispersal of the solar nebula and the differences in hydrogen content in the giant planets. Finally, we model the small bright objects ("proplyds") observed in the Orion Nebula as disks around young, low mass stars which axe externally illuminated by the UV photons from the nearby massive star theta(sup 1)C.
Document ID
20010056690
Acquisition Source
Ames Research Center
Document Type
Preprint (Draft being sent to journal)
Authors
Hollenbach, David
(NASA Ames Research Center Moffett Field, CA United States)
DeVincenzi, Donald L.
Date Acquired
August 20, 2013
Publication Date
January 1, 2001
Subject Category
Astrophysics
Funding Number(s)
PROJECT: RTOP 344-04-10-02
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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