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Dispersal of Disk Around Young StarsYoung stars produce sufficient ultraviolet photon luminosity and mechanical luminosity in their winds to significantly affect the structure and evolution of the accretion disks surrounding them. The Lyman continuum photons create a nearly static, ionized, isothermal 10(exp 4) K atmosphere forms above the neutral disk at small distances from the star. Further out, they create a photoevaporative flow which relatively rapidly destroys the disk. The resulting slow (10-50 km per second) ionized outflow, which persists for greater than or equal to 10(exp 5) years for disk masses Md approx. 0.3M*, 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 are externally illuminated by the UV photons from the nearby massive star.
Document ID
20010084184
Acquisition Source
Ames Research Center
Document Type
Preprint (Draft being sent to journal)
Authors
DeVincenzi, Donald L.
(NASA Ames Research Center Moffett Field, CA United States)
Hollenbach, David
(NASA Ames Research Center Moffett Field, CA United States)
Date Acquired
August 20, 2013
Publication Date
January 30, 2000
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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