PHOTOEVAPORATION OF CIRCUMSTELLAR DISKS BY FAR-ULTRAVIOLET, EXTREME-ULTRAVIOLET AND X-RAY RADIATION FROM THE CENTRAL STAR

By U. Gorti, D. Hollenbach. 2008

247 citations recorded by the source corpus.

We calculate the rate of photoevaporation of a circumstellar disk by energetic radiation (far-UV (FUV), 6 eV 0.1 keV) from its central star. We focus on the effects of FUV and X-ray photons since EUV photoevaporation has been treated previously, and consider central star masses in the range 0.3–7 M☉. Contrary to the EUV photoevaporation scenario, which creates a gap at about rg ∼ 7(M*/M☉) AU and then erodes the outer disk from inside out, we find that FUV photoevaporation predominantly removes less bound gas from the outer disk. Heating by FUV photons can cause significant erosion of the outer disk where most of the mass is typically located. X-rays indirectly increase the mass-loss rates (by a factor of ∼2) by ionizing the gas, thereby reducing the positive charge on grains and polycyclic aromatic hydrocarbons and enhancing FUV-induced grain photoelectric heating. FUV and X-ray photons may create a gap in the disk at ∼10 AU under favorable circumstances. Photoevaporation timescales for M* ∼ 1 M☉ stars are estimated to be ∼106 years, after the onset of disk irradiation by FUV and X-rays. Disk lifetimes do not vary much for stellar masses in the range 0.3–3 M☉. More massive stars (≳7 M☉) lose their disks rapidly (in ∼105 years) due to their high EUV and FUV fields. Disk lifetimes are shorter for shallow surface density distributions and when the dust opacity in the disk is reduced by processes such as grain growth or settling. The latter suggests that the photoevaporation process may accelerate as the dust disk evolves.

Subfields: Astronomy and Astrophysics, Spectroscopy

View Paper: https://www.semanticscholar.org/paper/6bd31dc1fc31a3461b63af698f64c3821050181b

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Astronomy and Astrophysics

1. Philip Armitage
2. Xue-Ning Bai
3. J. Owen
4. L. Hartmann
5. G. Herczeg
6. C. Clarke
7. N. Calvet
8. Barbara Ercolano

In Spectroscopy

1. C. Clarke
2. J. Owen
3. Barbara Ercolano
4. Philip Armitage
5. N. Calvet
6. G. Herczeg
7. L. Hartmann
8. Fred C. Adams

Citations in the corpus

• A spectroscopic survey of Herbig Ae/Be stars with X-shooter – I. Stellar parameters and accretion rates (2015, background): “Modelling of disc dispersion through photoevaporation suggests that the disc lifetimes are indeed shorter for more massive stars (Gorti & Hollenbach 2009).”
• The Birth Environment of the Solar System (2010, background): “However, the EUV radiation is more easily absorbed, so that both sources of radiation must generally be considered (see Gorti & Hollenbach 2009, Ercolano et al. 2009).”
• Dynamics of Protoplanetary Disks (2010, background): “The thermal structure depends upon the irradiating spectrum, grain physics, chemical processes, and cooling by atomic and (where molecules are present) molecular lines (e.g. Gorti & Hollenbach 2008; Woitke, Kamp & Thi 2009).”
• WIND-DRIVEN ACCRETION IN PROTOPLANETARY DISKS. I. SUPPRESSION OF THE MAGNETOROTATIONAL INSTABILITY AND LAUNCHING OF THE MAGNETOCENTRIFUGAL WIND (2013, background): “In the meantime, the FUV photons are also important driver of photoevaporation (Gorti & Hollenbach 2009; Owen et al. 2012), which is not considered in this work.”
• On the theory of disc photoevaporation (2011, methodology): “This parametrization reproduces the temperature structure of the region directly irradiated by FUV in Richling & Yorke (2000, their model A) and the temperature structure listed for the ‘launching point’ of the calculations of Gorti & Hollenbach (2008).”
• Accretion onto Pre-Main-Sequence Stars (2016, background): “Models of disk evolution through viscous accretion predict a decline in accretion rate with age (Hartmann et al. 1998, Alexander & Armitage 2009, Gorti & Hollenbach 2009).”
• THE RUNTS OF THE LITTER: WHY PLANETS FORMED THROUGH GRAVITATIONAL INSTABILITY CAN ONLY BE FAILED BINARY STARS (2009, unknown): “Radiative transfer models such as Gorti & Hollenbach (2009) have calculated that photoevaporation by the central star will become important at radii of ∼ 100 AU around one Myr for an A star (see also Ercolano et al. 2009).”
• TRANSITIONAL DISKS AS SIGNPOSTS OF YOUNG, MULTIPLANET SYSTEMS (2011, background): “However, extreme UV photoevaporation only drives disk dissipation when the viscous mass flow through the disk becomes weaker than the photoevaporative flow, estimated by Gorti & Hollenbach (2009) as ṀEUV .”
• TIME EVOLUTION OF VISCOUS CIRCUMSTELLAR DISKS DUE TO PHOTOEVAPORATION BY FAR-ULTRAVIOLET, EXTREME-ULTRAVIOLET, AND X-RAY RADIATION FROM THE CENTRAL STAR (2009, methodology): “GH09 calculate the rate of photoevaporation of a circumstellar disk by energetic radia- tion (EUV, FUV and X-rays) from its central star, using detailed but static disk structure models (Gorti & Hollenbach 2008, hereafter GH08).”
• The warm gas atmosphere of the HD 100546 disk seen by Herschel - Evidence of a gas-rich, carbon-poor atmosphere? (2012, unknown): “…Glassgold et al. (2004), Kamp & Dullemond (2004), Gorti & Hollenbach (2004), Nomura & Millar (2005), Aikawa & Nomura (2006), Jonkheid et al. (2004), Jonkheid et al. (2006), Jonkheid et al. (2007), Gorti & Hollenbach (2008), Woitke et al. (2009a), Woods & Willacy (2009), and Ercolano et al. (2009a).”