Photoevaporation of Grain-Depleted Protoplanetary Disks around Intermediate-Mass Stars: Investigating Possibility of Gas-Rich Debris Disks as Protoplanetary Remnants

Abstract

Debris disks are classically considered to be gas-less systems, but recent (sub)millimeter observations have detected tens of those with rich gas content. The origin of the gas component remains unclear; namely, it can be protoplanetary remnants and/or secondary products deriving from large bodies. In order to be protoplanetary in origin, the gas component of the parental protoplanetary disk is required to survive for $\gtrsim 10\mathrm{Myr}$. However, previous models predict $\lesssim 10\mathrm{Myr}$ lifetimes because of efficient photoevaporation at the late stage of disk evolution. In the present study, we investigate photoevaporation of gas-rich, optically-thin disks around intermediate-mass stars at a late stage of the disk evolution. The evolved system is modeled as those where radiation force is sufficiently strong to continuously blow out small grains ($\lesssim 4\mu \mathrm{m}$), which are an essential component for driving photoevaporation via photoelectric heating induced by stellar far-ultraviolet (FUV). We find that the grain depletion reduces photoelectric heating, so that FUV photoevaporation is not excited. Extreme-ultraviolet (EUV) photoevaporation is dominant and yields a mass-loss rate of $2$--$5\times 10^{-10}({\Phi }_{\mathrm{EUV}}/10^{41}{\mathrm{s}}^{-1}{)}^{1/2}{M}_{\odot }{\mathrm{yr}}^{-1}$, where ${\Phi }_{\mathrm{EUV}}$ is the EUV emission rate. The estimated lifetimes of the gas component are $\sim 50(M_{\mathrm{disk}}/10^{-2}{M}_{\odot })({\Phi }_{\mathrm{EUV}}/10^{41}{\mathrm{s}}^{-1}{)}^{1/2}\mathrm{Myr}$ and depend on the ``initial'' disk mass at the point small grains have been depleted in the system. With an order estimation, we show that the gas component can survive for a much longer time around A-type stars than lower-mass stars. This trend is consistent with the higher frequency of gas-rich debris disks around A-type stars, implying the possibility of the gas component being protoplanetary remnants.

Accepted for publication in ApJ

References in corpus (27)

• PLUTO: a Numerical Code for Computational Astrophysics
• Photoevaporation of protoplanetary discs II: evolutionary models and observable properties
• Transience of hot dust around sun-like stars
• Global simulations of protoplanetary disks with ohmic resistivity and ambipolar diffusion
• Molecular Gas Clumps from the Destruction of Icy Bodies in the $\beta$ Pictoris Debris Disk
• Evolution of Protoplanetary Discs with Magnetically Driven Disc Winds
• X-ray irradiated protoplanetary disk atmospheres I: Predicted emission line spectrum and photoevaporation
• [CII] 158$\mu$m Emission and Metallicity in PDRs
• The Impact of Dust Evolution and Photoevaporation on Disk Dispersal
• Line Emission from Gas in Optically Thick Dust Disks around Young Stars
• Detection of exocometary CO within the 440 Myr-old Fomalhaut belt: a similar CO+CO${}_2$ ice abundance in exocomets and Solar System comets
• Molecular gas in debris disks around young A-type stars
• Five steps in the evolution from protoplanetary to debris disk
• Global Hydromagnetic Simulations of Protoplanetary Disks with Stellar Irradiation and Simplified Thermochemistry
• Hydrodynamic Photoevaporation of Protoplanetary Disks with Consistent Thermochemistry
• Dispersal of protoplanetary disks by the combination of magnetically driven and photoevaporative winds
• Photoevaporative Dispersal of Protoplanetary Disks around Evolving Intermediate-mass Stars
• Population synthesis of exocometary gas around A stars
• Radiation pressure clear-out of dusty photoevaporating discs
• Radiation hydrodynamics simulations of protoplanetary disks: Stellar mass dependence of the disk photoevaporation rate
• Radiation-Hydrodynamical Models of X-ray Photoevaporation in Carbon Depleted Circumstellar Discs
• Makemake + Sedna: A Continuum Radiation Transport and Photoionization Framework for Astrophysical Newtonian Fluid Dynamics
• Debris disc formation induced by planetary growth
• Asymmetric mid-plane gas in ALMA images of HD~100546
• The X-Ray Origin of Herbig AeBe Systems: New Insights
• Modelling the Spatial Distribution and Origin of CO Gas in Debris Disks
• First detection of submillimeter-wave [13C I] 3P1-3P0 emission in a gaseous debris disk of 49 Ceti with ALMA

Cited by in corpus (20)

• The growth and migration of massive planets under the influence of external photoevaporation
• Lack of other molecules in CO-rich debris discs: is it primordial or secondary gas?
• Disc population synthesis: Decrease in the solid mass reservoir through pebble drift
• Primordial or Secondary? Testing models of debris disk gas with ALMA
• Vertical evolution of exocometary gas: I. How vertical diffusion shortens the CO lifetime
• The ALMA survey to Resolve exoKuiper belt Substructures (ARKS) I: Motivation, sample, data reduction, and results overview
• Morphology of the gas-rich debris disk around HD 121617 with SPHERE observations in polarized light
• X-Shooter Survey of Young Intermediate Mass Stars -- I. Stellar Characterization and Disc Evolution
• The ALMA survey to Resolve exoKuiper belt Substructures (ARKS) IV: CO gas imaging and overview
• Accretion of aerodynamically large pebbles
• Photoevaporation Can Reproduce Extended ${\mathrm{H}}_2$ Emission from Protoplanetary Disks Imaged by JWST MIRI
• A Constraint on the Amount of Hydrogen from the CO Chemistry in Debris Disks
• The survivorship bias of protoplanetary disc populations
• The ALMA survey to Resolve exoKuiper belt Substructures (ARKS) VIII: A dust arc and non-Keplerian gas kinematics in HD 121617
• The ALMA survey to Resolve exoKuiper belt Substructures (ARKS). X. Interpreting the peculiar dust rings around HD 131835
• Discovery of carbon monoxide emission from five debris disks around young A-type stars
• Jets in Low-Mass Protostars
• Water vapor as a probe of the origin of gas in debris disks
• HD 44892: The youngest (or oldest?) gas-harbouring debris disc around an intermediate mass star
• Resolving the large exoKuiper belt of the HD 126062 debris disc and extended gas emission in its vicinity