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          Institute: MPI für Astronomie     Collection: Publikationen_mpia     Display Documents

ID: 448142.0, MPI für Astronomie / Publikationen_mpia
Time evolution of viscous circumstellar disks due to photoevaporation by far-ultraviolet, extreme-ultraviolet, and X-ray radiation from the central star
Authors:Gorti, U.; Dullemond, C. P.; Hollenbach, D.
Date of Publication (YYYY-MM-DD):2009
Title of Journal:The Astrophysical Journal
Journal Abbrev.:ApJ
Start Page:1237
End Page:1251
Review Status:Peer-review
Audience:Experts Only
Abstract / Description:We present the time evolution of viscously accreting circumstellar disks as they are irradiated by ultraviolet and X-ray photons from a low-mass central star. Our model is a hybrid of a one-dimensional (1D) time-dependent viscous disk model coupled to a 1+1D disk vertical structure model used for calculating the disk structure and photoevaporation rates. We find that disks of initial mass 0.1 M sun around ~1 M sun stars survive for ~4 × 106 yr, assuming a viscosity parameter alpha = 0.01, a time-dependent FUV luminosity L FUV ~ 10-2-10-3 L sun and with X-ray and EUV luminosities LX ~ L EUV ~ 10-3 L sun. We find that FUV/X-ray-induced photoevaporation and viscous accretion are both important in depleting disk mass. Photoevaporation rates are most significant at ~1-10 AU and at gsim30 AU. Viscosity spreads the disk which causes mass loss by accretion onto the central star and feeds mass loss by photoevaporation in the outer disk. We find that FUV photons can create gaps in the inner, planet-forming regions of the disk (~1-10 AU) at relatively early epochs in disk evolution while disk masses are still substantial. EUV and X-ray photons are also capable of driving gaps, but EUV can only do so at late, low accretion-rate epochs after the disk mass has already declined substantially. Disks around stars with predominantly soft X-ray fields experience enhanced photoevaporative mass loss. We follow disk evolution around stars of different masses, and find that disk survival time is relatively independent of mass for stars with M *lsim 3 M sun; for M *gsim 3 M sun the disks are short-lived (~105 yr).
Free Keywords:accretion; accretion disks; planetary systems: protoplanetary disks; stars: formation; stars: pre-main-sequence; ultraviolet: stars; X-rays: stars
External Publication Status:published
Document Type:Article
Communicated by:N. N.
Affiliations:MPI für Astronomie
Identifiers:URL:http://adsabs.harvard.edu/abs/2009ApJ...705.1237G [ID No:1]
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