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Record 1 of 16743
Disk Evaporation in Star Forming Regions
Author and Affiliation:
Hollenbach, David(NASA Ames Research Center, Moffett Field, CA United States)
DeVincenzi, Donald L. [Technical Monitor]
Abstract: Young 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/s) ionized outflow, which persists for approx. greater than 10(exp 5) years for disk masses M(sub d) approx. 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 apply the results to Ae and Be stars in order to determine the lifetimes of disks around such stars. 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 Theta(sup 1) C.
Publication Date: Jan 01, 2000
Document ID:
20010007247
(Acquired Jan 19, 2001)
Subject Category: ASTROPHYSICS
Document Type: Preprint
Meeting Information: 23-29 Oct. 2000; Amsterdam; Netherlands
Contract/Grant/Task Num: RTOP 344-04-10-02
Financial Sponsor: NASA Ames Research Center; Moffett Field, CA United States
Organization Source: NASA Ames Research Center; Moffett Field, CA United States
Description: 1p; In English
Distribution Limits: Unclassified; Publicly available; Unlimited
Rights: No Copyright
NASA Terms: A STARS; H II REGIONS; ACCRETION DISKS; EVAPORATION; GAS GIANT PLANETS; HYDROGEN MASERS; STELLAR MASS; ORION NEBULA; CONTINUUMS; DISTANCE; ILLUMINATING; MASSIVE STARS; PHOTONS; DISPERSING; STELLAR LUMINOSITY
Availability Source: Other Sources
Availability Notes: Abstract Only
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