Accreting Transition Discs with large cavities created by X-ray photoevaporation in C and O depleted discs

Abstract

Circumstellar discs with large dust depleted cavities and vigorous accretion onto the central star are often considered signposts for (multiple) giant planet formation. In this letter we show that X-ray photoevaporation operating in discs with modest (factors 3-10) gas-phase depletion of Carbon and Oxygen at large radii (> 15 AU) yield the inner radius and accretion rates for most of the observed discs, without the need to invoke giant planet formation. We present one-dimensional viscous evolution models of discs affected by X-ray photoevaporation assuming moderate gas-phase depletion of Carbon and Oxygen, well within the range reported by recent observations. Our models use a simplified prescription for scaling the X-ray photoevaporation rates and profiles at different metallicity, and our quantitative result depends on this scaling. While more rigorous hydrodynamical modelling of mass loss profiles at low metallicities is required to constrain the observational parameter space that can be explained by our models, the general conclusion that metal sequestering at large radii may be responsible for the observed diversity of transition discs is shown to be robust. Gap opening by giant planet formation may still be responsible for a number of observed transition discs with large cavities and very high accretion rate.

5 pages; 2 figures; accepted as a Letter to Monthly Notices of the Royal Astronomical Society (MNRASL)

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Cited by in corpus (12)

• The dispersal of protoplanetary discs. II: Photoevaporation models with observationally derived irradiating spectra
• Radiation pressure clear-out of dusty photoevaporating discs
• Large gaps and high accretion rates in photoevaporative transition disks with a dead zone
• Revisiting migration in a disc cavity to explain the high eccentricities of warm Jupiters
• Radiation-Hydrodynamical Models of X-ray Photoevaporation in Carbon Depleted Circumstellar Discs
• GIARPS High-resolution Observations of T Tauri stars (GHOsT). III. A pilot study of stellar and accretion properties
• Dust Traps and the Formation of Cavities in Transition Discs: A millimetre to sub-millimetre comparison survey
• The circumstellar environment of EX Lup: the SPHERE and SINFONI views
• Millimeter emission in photoevaporating disks is determined by early substructures
• Modelling thermochemical processes in protoplanetary disks I: numerical methods
• Observability of Photoevaporation Signatures in the Dust Continuum Emission of Transition Discs
• Formation of ring-like structures in flared α-discs with X-ray/FUV photoevaporation