Submillimeter lines from circumstellar disks around pre-main sequence stars

Abstract

Observations of submillimeter lines of CO (up to J=6-5), HCO+, HCN (up to J=4-3) and their isotopes from circumstellar disks around low mass pre-main sequence stars are presented. The different line ratios and optical depths indicate that most of the observed line emission arises from an intermediate disk layer with high densities of 1E6-1E8 cm-3 and moderately warm temperatures in the outer regions. The data are compared with three disk models from the literature using a full 2D Monte Carlo radiative transfer code. The abundances of the molecules are constrained from the more optically thin 13C species and indicate depletions of 1-30 for LkCa 15 and very high depletions of > 100 for TW Hya with respect to dark cloud abundances. Evidence for significant freeze-out (factors 10 or larger) of CO and HCO+ onto grain surfaces at temperatures below 22 K is found, but the abundances of these molecules must also be low in the warmer upper layer, most likely as a result of photodissociation. A warm upper layer near the surface of a flaring disk heated by stellar and interstellar radiation is an appropriate description of the observations of TW Hya. LkCa 15 seems to be cooler at the surface, perhaps due to dust settling.

15 pages, 8 figures. Accepted for publication in A&A

Cited by in corpus (113)

• Protoplanetary Disks and Their Evolution
• Circumstellar Dust Disks in Taurus-Auriga: The Submillimeter Perspective
• Our astrochemical heritage
• 2021 Census of Interstellar, Circumstellar, Extragalactic, Protoplanetary Disk, and Exoplanetary Molecules
• 2018 Census of Interstellar, Circumstellar, Extragalactic, Protoplanetary Disk, and Exoplanetary Molecules
• Observations of Protoplanetary Disk Structures
• Radiation thermo-chemical models of protoplanetary disks I. Hydrostatic disk structure and inner rim
• Molecules with ALMA at Planet-forming Scales (MAPS) I: Program Overview and Highlights
• The TW Hya Disk at 870 microns: Comparison of CO and Dust Radial Structures
• A Parametric Modeling Approach to Measuring the Gas Masses of Circumstellar Disks
• Complex organic molecules in protoplanetary disks
• Astrochemistry and compositions of planetary systems
• Warm Molecular Layers in Protoplanetary Disks
• Resolved gas cavities in transitional disks inferred from CO isotopologues with ALMA
• Survival of molecular gas in cavities of transition disks (I. CO)
• Organic molecules in protoplanetary disks around TTauri and HerbigAe stars
• CO emission from discs around isolated HAeBe and Vega-excess stars
• A Spatially Resolved Vertical Temperature Gradient in the HD 163296 Disk
• Constraining the X-ray and Cosmic Ray Ionization Chemistry of the TW Hya Protoplanetary Disk: Evidence for a Sub-interstellar Cosmic Ray Rate
• The Radial Distribution of H2 and CO in TW Hya as Revealed by Resolved ALMA Observations of CO Isotopologues
• The FUV spectrum of TW Hya. I. Observations of H${}_2$ Fluorescence
• Chemical Processes in Protoplanetary Disks
• Volatile carbon locking and release in protoplanetary disks. A study of TW Hya and HD 100546
• Imaging the Disk around TW Hya with the Submillimeter Array
• Lupus disks with faint CO isotopologues: low gas/dust or large carbon depletion?
• Protoplanetary disk masses from CO isotopologues line emission
• Mass measurements in protoplanetary disks from hydrogen deuteride
• Gas density drops inside dust cavities of transitional disks around young stars observed with ALMA
• Ices in the edge-on disk CRBR 2422.8-3423: Spitzer spectroscopy and Monte Carlo radiative transfer modeling
• The Effects of UV Continuum and Lyman alpha Radiation on the Chemical Equilibrium of T Tauri Disks
• Disk Imaging Survey of Chemistry with SMA (DISCS): I. Taurus Protoplanetary Disk Data
• Chemical Processes in Protoplanetary Disks II. On the importance of photochemistry and X-ray ionization
• Line Emission from Gas in Optically Thick Dust Disks around Young Stars
• Determining protoplanetary disk gas masses from CO isotopologues line observations
• Axi-symmetric models of ultraviolet radiative transfer with applications to circumstellar disk chemistry
• Molecules with ALMA at Planet-forming Scales (MAPS) IV: Emission Surfaces and Vertical Distribution of Molecules
• c2d Spitzer IRS Spectra of Disks around T Tauri Stars. III. [Ne II], [Fe I], and H_2 gas-phase lines
• CO destruction in protoplanetary disk midplanes: inside versus outside the CO snow surface
• An ALMA Survey of CO isotopologue emission from Protoplanetary Disks in Chamaeleon I
• Radiation thermo-chemical models of protoplanetary disks II. Line diagnostics
• Resolving the CO Snow Line in the Disk around HD 163296
• The gas temperature in flaring disks around pre-main sequence stars
• Emission Lines from the Gas Disk around TW Hydra and the Origin of the Inner Hole
• Continuum and CO/HCO+ Emission from the Disk Around the T Tauri Star LkCa 15
• Isotope selective photodissociation of N2 by the interstellar radiation field and cosmic rays
• Robustness of N2H+ as tracer of the CO snowline
• Bright C2H emission in protoplanetary disks in Lupus: high volatile C/O>1 ratios
• The Distribution and Excitation of CH${}_3$CN in a Solar Nebula Analog
• Chemistry in disks I - Deep search for N${}_2$H${}^{+}$ in the protoplanetary disks around LkCa 15, MWC 480, and DM Tau
• CO J=6-5 observations of TW Hya with the SMA
• An ALMA survey of DCN/H${}^{13}$CN and DCO${}^{+}$/H${}^{13}$CO${}^{+}$ in protoplanetary disks
• Chemistry in Protoplanetary Disks: A Sensitivity Analysis
• Fast Radial Flows in Transition Disk Holes
• HD far infrared emission as a measure of protoplanetary disk mass
• CID: Chemistry in disks VI.sulfur-bearing molecules in the protoplanetary disks surrounding LkCa15, MWC480, DM Tau, and GO Tau
• Empirical Temperature Measurement in Protoplanetary Disks
• Millimeter observations and modeling of the AB Aurigae system
• Disks around the Young Stars TW Hya and HD 100546 Imaged at 3.4 Millimeters with the Australia Telescope Compact Array
• Detection of DCO+ in a circumstellar disk
• Detection of CH+ emission from the disc around HD100546
• Chemistry in Disks. V: CN and HCN in proto-planetary disks
• Molecules with ALMA at Planet-forming Scales (MAPS). IX. Distribution and Properties of the Large Organic Molecules HC${}_3$N, CH${}_3$CN, and $c$-C${}_3$H${}_2$
• Unveiling the physical conditions of the youngest disks: A warm embedded disk in L1527
• Interferometric Observations of Formaldehyde in the Protoplanetary Disk around LkCa15
• First detection of H${}_2$S in a protoplanetary disk. The dense GG Tau A ring
• High Resolution 4.7 um Keck/NIRSPEC Spectra of Protostars. I: Ices and Infalling Gas in the Disk of L1489 IRS
• Measurements of water surface snow lines in classical protoplanetary disks
• Ro-vibrational excitation of an organic molecule (HCN) in protoplanetary disks
• A dust and gas cavity in the disc around CQ Tau revealed by ALMA
• Warm molecular gas and kinematics in the disc around HD 100546
• The TW Hya Rosetta Stone Project III: Resolving the Gaseous Thermal Profile of the Disk
• Directly tracing the vertical stratification of molecules in protoplanetary disks
• Variable H${}^{13}$CO${}^{+}$ Emission in the IM Lup Disk: X-ray Driven Time-Dependent Chemistry?
• Molecular line radiative transfer in protoplanetary disks: Monte Carlo simulations versus approximate methods
• The chemistry of disks around T Tauri and Herbig Ae/Be stars
• Dust Size Growth and Settling in a Protoplanetary Disk
• Rings and gaps in protoplanetary disks: planets or snowlines?
• Using Ice and Dust Lines to Constrain the Surface Densities of Protoplanetary Disks
• The Disc Miner II: Revealing Gas substructures and Kinematic signatures from Planet-disc interaction through line profile analysis
• Disk masses around solar-mass stars are underestimated by CO observations
• A novel way of measuring the gas disk mass of protoplanetary disks using N2H+ and C18O
• Gas temperature structure across transition disk cavities
• A new raytracer for modeling AU-scale imaging of lines from protoplanetary disks
• Probing the 2D temperature structure of protoplanetary disks with Herschel observations of high-J CO lines
• Determining the mid-plane conditions of circumstellar discs using gas and dust modelling: a study of HD 163296
• exoALMA V: Gaseous Emission Surfaces and Temperature Structures
• Chemistry in Disks. II. -- Poor molecular content of the AB Aur disk
• Probing the radial temperature structure of protoplanetary disks with Herschel/HIFI
• Molecular Line Emission from Gravitationally Unstable Protoplanetary Disks
• Tracing pebble drift and trapping using radial carbon depletion profiles in protoplanetary disks
• Searching for Gas-Rich Disks around T Tauri Stars in Lupus
• Complex organic molecules along the accretion flow in isolated and externally irradiated protoplanetary disks
• Circumstellar disks and planets. Science cases for next-generation optical/infrared long-baseline interferometers
• Asymmetric mid-plane gas in ALMA images of HD~100546
• Signatures of warm carbon monoxide in protoplanetary discs observed with Herschel SPIRE
• Resolved molecular line observations reveal an inherited molecular layer in the young disk around TMC1A
• Odin observations of water in molecular outflows and shocks
• ASTE Submillimeter Observations of a Young Stellar Object Condensation in Cederblad 110
• First Detection of [C I] ${}^3$P${}_1$-${}^3$P${}_0$ Emission from a Protoplanetary Disk
• Exploring HNC and HCN line emission as probes of the protoplanetary disk temperature
• A molecular outflow evidencing star formation activity in the vicinity of the HII region G034.8-0.7 and the SNR W44
• Vertically extended and asymmetric CN emission in the Elias 2-27 protoplanetary disk
• Probing the protoplanetary disk gas surface density distribution with ${}^{13}$CO emission
• The protoplanetary disk of FT Tauri: multi-wavelength data analysis and modeling
• Disentangling protoplanetary disk gas mass and carbon depletion through combined atomic and molecular tracers
• Mass determination of protoplanetary disks from dust evolution
• An Unbiased 1.3 mm Emission Line Survey of the Protoplanetary Disk Orbiting LkCa 15
• First detections of H13CO+ and HC15N in the disk around HD 97048: Evidence for a cold gas reservoir in the outer disk
• Chemistry During the Gas-rich Stage of Planet Formation
• HCO+ Detection of Dust-Depleted Gas in the Inner Hole of the LkCa 15 Pre-Transitional Disk
• The role of OH in the chemical evolution of protoplanetary disks II. Gas-rich environments
• Continuing to Hide Signatures of Gravitational Instability in Protoplanetary Discs with Planets
• First Detection of HC5N in a Class II Disk around TW Hya