Photoevaporation of Circumstellar Disks around Young Stars

By A. Font, Ian G. McCarthy, D. Johnstone, D. Ballantyne. 2004

179 citations recorded by the source corpus.

We examine the ability of photoevaporative disk winds to explain the low-velocity components observed in the forbidden line spectra of low-mass T Tauri stars. Using the analytic model of Shu and coworkers and Hollenbach and coworkers as a basis, we examine the characteristics of photoevaporative outflows with hydrodynamic simulations. General results from the simulations agree well with the analytic predictions, although some small differences are present. Most importantly, the flow of material from the disk surface develops at smaller radii than in the analytic approximations, and the flow velocity from the disk surface is only one-third the sound speed. A detailed presentation of observational consequences of the model is given, including predicted line widths, blueshifts, and integrated luminosities of observable sulfur and nitrogen emission lines. We demonstrate that these predictions are in agreement with current observational data on the low-velocity forbidden line emission of ionized species from T Tauri stars. This is in contrast to magnetic wind models, which systematically underpredict these forbidden line luminosities. However, the present model cannot easily account for the luminosities of neutral oxygen lines in T Tauri stars.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/0f972b3daca2719db5071b4a06406c9011b757d3

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Citations in the corpus

TIME EVOLUTION OF VISCOUS CIRCUMSTELLAR DISKS DUE TO PHOTOEVAPORATION BY FAR-ULTRAVIOLET, EXTREME-ULTRAVIOLET, AND X-RAY RADIATION FROM THE CENTRAL STAR (2009, methodology): “We note that the flows induced by FUV/X-rays at these regions of the disk are predominantly subsonic (Adams et al. 2004).”
PHOTOEVAPORATION OF CIRCUMSTELLAR DISKS BY FAR-ULTRAVIOLET, EXTREME-ULTRAVIOLET AND X-RAY RADIATION FROM THE CENTRAL STAR (2008, background): “In fact, substantial mass fluxes occur for r > rcr where rcr ∼ 0.1rg–0.2rg (also see Begelman et al. 1983; Liffman 2003; Font et al. 2004).”
On the theory of disc photoevaporation (2011, methodology): “However, in order to be consistent with the previous EUV-only literature (Hollenbach et al. 1994; Clarke et al. 2001; Font et al. 2004; Alexander et al. 2006a), we separately fix Rg = 8.9(1/1 M ) au.”
Protoplanetary disc evolution and dispersal: the implications of X-ray photoevaporation (2010, unknown): “…Hartigan et al 1995; Pascucci et al 2009) is well reproduced by the XPE model for all of the low ionisation and atomic diagnostics considered (Ercolano & Owen, 2010), an improvement over the EUV photoevaporation model which cannot reproduce the OI 6300Å line intensities (e.g. Font et al 2004).”
Photoevaporation of protoplanetary discs - II. Evolutionary models and observable properties (2006, background): “More recent studies have extended the study of the details in a number of ways (Richling & Yorke 1997; Johnstone, Hollenbach & Bally 1998; Font et al. 2004), and recent hydrodynamic modelling has resulted in slight modification of the quantitative results.”
X-Ray-Irradiated Protoplanetary Disk Atmospheres. I. Predicted Emission-Line Spectrum and Photoevaporation (2008, background): “More recent works by Liffman (2003) and Font et al. (2004) also find that an EUV-driven wind is launched from well inside the gravitational radius (as defined by Hollenbach et al., 1994).”
Dust dynamics during protoplanetary disc clearing (2007, methodology): “R crit is the " critical radius " at which the gap opens, which is given by (Liffman 2003; Font et al. 2004; Dullemond et al. 2006) R crit ≃ 1.4 M * 1M ⊙ AU , (7) and is approximately one-fifth of the " gravitational radius " defined by Hollenbach et al. (1994).”
Radiation-hydrodynamic models of X-ray and EUV photoevaporating protoplanetary discs (2009, methodology): “Likewise, the X-EUV model needs to be assessed with regard to the production of forbidden line emission (including O[I]) as in the study of Font et al. (2004) for the EUV case.”
Theory of Star Formation (2007, background): “Pressure gradients enable flows to emerge down to (0.1− 0.2)rg (Begelman, McKee, & Shields, 1983; Font et al., 2004; Adams et al., 2004).”
Dynamics of Protoplanetary Disks (2010, background): “…to the star (i.e. before any inner hole develops), the mass loss rate can be evaluated by adopting the analytic scaling of Hollenbach et al. (1994), scaled down by a factor of three as suggested by the numerical results of Font et al. (2004), Ṁwind ≈ 1.4× 10−10 ( Φ 1041 s−1 )1/2(M∗ M )1/2 M yr −1.”
Photoevaporation of protoplanetary discs – I. Hydrodynamic models (2006, background): “This suggests that the typical launch velocity is around 0.4 times the sound speed, a value consistent with numerical simulations of the photoevaporative wind driven by the diffuse radiation field (Font et al. 2004).”