The Evolution of Protoplanetary Disks: Probing the Inner Disk of Very Low Accretors

Abstract

We report FUV, optical, and NIR observations of three T Tauri stars in the Orion OB1b subassociation with H$\alpha$ equivalent widths consistent with low or absent accretion and various degrees of excess flux in the mid-infrared. We aim to search for evidence of gas in the inner disk in HST ACS/SBC spectra, and to probe the accretion flows onto the star using H$\alpha$ and He I $\lambda$10830 in spectra obtained at the Magellan and SOAR telescopes. At the critical age of 5 Myr, the targets are at different stages of disk evolution. One of our targets is clearly accreting, as shown by redshifted absorption at free-fall velocities in the He I line and wide wings in H$\alpha$; however, a marginal detection of FUV H${}_2$ suggests that little gas is present in the inner disk, although the spectral energy distribution indicates that small dust still remains close to the star. Another target is surrounded by a transitional disk, with an inner cavity in which little sub-micron dust remains. Still, the inner disk shows substantial amounts of gas, accreting onto the star at a probably low, but uncertain rate. The third target lacks both a He I line or FUV emission, consistent with no accretion or inner gas disk; its very weak IR excess is consistent with a debris disk. Different processes occurring in targets with ages close to the disk dispersal time suggest that the end of accretion phase is reached in diverse ways.

arXiv comment13 pages, 3 figures. Accepted for publication in The Astrophysical Journal

References in corpus (40)

• Astropy: A Community Python Package for Astronomy
• Gaia Data Release 2. Summary of the contents and survey properties
• The Wide-field Infrared Survey Explorer (WISE): Mission Description and Initial On-orbit Performance
• Intrinsic Colors, Temperatures, and Bolometric Corrections of Pre-Main Sequence Stars
• Optimal Techniques in Two-dimensional Spectroscopy: Background Subtraction for the 21st Century
• Very Low Mass Stars and Brown Dwarfs in Taurus-Auriga
• Evidence for a developing gap in a 10 Myr old protoplanetary disk
• Timescale of Mass Accretion in Pre-Main-Sequence Stars
• Accretion in Brown Dwarfs: an Infrared View
• Evidence for Mass-dependent Circumstellar Disk Evolution in the 5 Myr-old Upper Scorpius OB Association
• Protoplanetary disk lifetimes vs stellar mass and possible implications for giant planet populations
• A Spitzer view of protoplanetary disks in the gamma Velorum cluster
• Probing T Tauri Accretion and Outflow with 1 Micron Spectroscopy
• Accretion Rates for T Tauri Stars Using Nearly Simultaneous Ultraviolet and Optical Spectra
• The Evolution of Early-Type Galaxies in Distant Clusters II: Internal Kinematics of 55 Galaxies in the z=0.33 Cluster CL1358+62
• Herbig Ae/Be Stars in nearby OB associations
• The MagE Spectrograph
• The Gaia FGK Benchmark Stars - High resolution spectral library
• The CIDA Variability Survey of Orion OB1. I: the low-mass population of Ori OB 1a and 1b
• Temperaments of young stars: Rapid mass-accretion rate changes in T Tauri and Herbig Ae stars
• Probing the Dust and Gas in the Transitional Disk of CS Cha with Spitzer
• Planet Formation in AB Aurigae: Imaging of the inner gaseous Spirals observed inside the Dust Cavity
• A Far-ultraviolet Atlas of Low-resolution Hubble Space Telescope Spectra of T Tauri Stars
• A New Probe of the Planet-Forming Region in T Tauri Disks
• Stellar Mass Dependent Disk Dispersal
• Multidimensional models of hydrogen and helium emission line profiles for classical T Tauri Stars: method, tests and examples
• Origins of the H, He I, and Ca II Line Emission in Classical T Tauri Stars
• The Origins of Fluorescent H2 Emission From T Tauri~Stars
• Redshifted Absorption at He I 10830 as a Probe of the Accretion Geometry of T Tauri Stars
• Far-Ultraviolet H2 Emission from Circumstellar Disks
• The Herschel DIGIT Survey of Weak-line T Tauri Stars: implications for disk evolution and dissipation
• SOAR Adaptive Module (SAM): seeing improvement with a UV laser
• A slowly accreting ~10 Myr old transitional disk in Orion OB1a
• A Herschel view of protoplanetary disks in the $\sigma$ Ori cluster
• The 1600 Angstrom Emission Bump in Protoplanetary Disks: A Spectral Signature of H${}_2$O Dissociation
• X-ray to NIR emission from AA Tauri during the dim state - Occultation of the inner disk and gas-to-dust ratio of the absorber
• Short Gas Dissipation Timescales: Diskless Stars in Taurus and Chamaeleon I
• Herschel PACS observations of 4-10 Myr old Classical T Tauri stars in Orion OB1
• Residual Gas & Dust Around Transition Objects and Weak T Tauri Stars
• Protoplanetary disk shadowing by gas infalling onto the young star AK Sco

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