Chemistry in Disks. III. -- Photochemistry and X-ray driven chemistry probed by the ethynyl radical (CCH) in DM Tau, LkCa 15, and MWC 480
arXiv:1003.5793 · doi:10.1088/0004-637X/714/2/1511
Abstract
We studied several representative circumstellar disks surrounding the Herbig Ae star MWC 480 and the T Tauri stars LkCa 15 and DM Tau at (sub-)millimeter wavelengths in lines of CCH. Our aim is to characterize photochemistry in the heavily UV-irradiated MWC 480 disk and compare the results to the disks around cooler T Tauri stars. We detected and mapped CCH in these disks with the IRAM Plateau de Bure Interferome- ter in the C- and D-configurations in the (1-0) and (2-1) transitions. Using an iterative minimization technique, the CCH column densities and excitation conditions are con- strained. Very low excitation temperatures are derived for the T Tauri stars. These values are compared with the results of advanced chemical modeling, which is based on a steady-state flared disk structure with a vertical temperature gradient, and a gas- grain chemical network with surface reactions. Both model and observations suggest that CCH is a sensitive tracer of the X-ray and UV irradiation. The predicted radial dependency and source to source variations of CCH column densities qualitatively agree with the observed values, but the predicted column densities are too low by a factor of several. The chemical model fails to reproduce high concentrations of CCH in very cold disk midplane as derived from the observed low excitation condition for both the (1-0) and (2-1) transitions.
23 pages, 9 figures, 3 tables, accepted for publication in ApJ
References in corpus (14)
- Formation of methyl formate and other organic species in the warm-up phase of hot molecular cores
- Coagulation, fragmentation and radial motion of solid particles in protoplanetary disks
- X-Ray Spectroscopy of Stars
- H2O and OH gas in the terrestrial planet-forming zones of protoplanetary disks
- Dust retention in protoplanetary disks
- Resolving the chemistry in the disk of TW Hydrae I. Deuterated species
- Cold CO in circumstellar disks: On the effects of photodesorption and vertical mixing
- A break in the gas and dust surface density of the disc around the T Tauri star IM Lup
- Gas-phase CO in protoplanetary disks: a challenge for turbulent mixing
- Chemistry in Protoplanetary Disks: A Sensitivity Analysis
- Chemistry and line emission from evolving Herbig Ae disks
- Turbulence driven diffusion in protoplanetary disks - chemical effects in the outer disk
- Protoplanetary Disk Evolution around the Triggered Star Forming Region Cepheus B
- Chemistry in Disks. II. -- Poor molecular content of the AB Aur disk
Cited by in corpus (67)
- Protoplanetary Disks and Their Evolution
- 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
- Molecules with ALMA at Planet-forming Scales (MAPS) I: Program Overview and Highlights
- Complex organic molecules in protoplanetary disks
- Chemistry in Disks. IV. Benchmarking gas-grain chemical models with surface reactions
- Chemical Processes in Protoplanetary Disks
- Chemical evolution of turbulent protoplanetary disks and the Solar nebula
- Hydrocarbon emission rings in protoplanetary disks induced by dust evolution
- Measuring turbulent motion in planet-forming disks with ALMA: A detection around DM Tau and non-detections around MWC 480 and V4046 Sgr
- Disk Imaging Survey of Chemistry with SMA: II. Southern Sky Protoplanetary Disk Data and Full Sample Statistics
- Imaging of a Transitional Disk Gap in Reflected Light: Indications of Planet Formation Around the Young Solar Analog LkCa 15
- DIGIT survey of far-infrared lines from protoplanetary disks I
- Sulfur chemistry in protoplanetary disks: CS and H2CS
- Systematic Variations of CO Gas Abundance with Radius in Gas-rich Protoplanetary Disks
- Bright C2H emission in protoplanetary disks in Lupus: high volatile C/O>1 ratios
- Cometary ices in forming protoplanetary disc midplanes
- Consistent dust and gas models for protoplanetary disks III. Models for selected objects from the FP7 DIANA project
- Protoplanetary Disk Structure With Grain Evolution: the ANDES Model
- X-ray impact on the protoplanetary disks around T Tauri stars
- Chemistry in disks. XI. Sulfur-bearing species as tracers of protoplanetary disk physics and chemistry: the DM Tau case
- Chemistry in Disks VIII: the CS molecule as an analytic tracer of turbulence in disks
- First detection of c-C3H2 in a circumstellar disk
- Chemistry in Disks X: The Molecular Content of Proto-planetary Disks in Taurus
- CID: Chemistry in disks VI.sulfur-bearing molecules in the protoplanetary disks surrounding LkCa15, MWC480, DM Tau, and GO Tau
- Chemistry in Disks. IX. Observations and modeling of HCO+ and DCO+ in DM Tau
- Detection of CH+ emission from the disc around HD100546
- Chemistry in Disks. V: CN and HCN in proto-planetary disks
- Impact of grain evolution on the chemical structure of protoplanetary disks
- The chemistry of disks around T Tauri and Herbig Ae/Be stars
- Chemistry in a gravitationally unstable protoplanetary disc
- Molecular line emission from a protoplanetary disk irradiated externally by a nearby massive star
- Unbiased mm-wave Line Surveys of TW Hya and V4046 Sgr: The Enhanced C2H and CN Abundances of Evolved Protoplanetary Disks
- Carbon-Chain Chemistry in the Interstellar Medium
- A novel way of measuring the gas disk mass of protoplanetary disks using N2H+ and C18O
- A Subarcsecond ALMA Molecular Line Imaging Survey of the Circumbinary, Protoplanetary Disk Orbiting V4046 Sgr
- The role of C/O in nitrile astrochemistry in PDRs and planet-forming disks
- A Ring of C2H in the Molecular Disk Orbiting TW Hya
- Exploring organic chemistry in planet-forming zones
- AB Aur, a Rosetta stone for studies of planet formation (I): chemical study of a planet-forming disk
- X-ray induced chemistry of water and related molecules in low-mass protostellar envelopes
- Herbig Stars: A Quarter Century of Progress
- Chemical Feedbacks of Pebble Growth: Impacts on CO depletion and C/O ratios
- Molecular content of the circumstellar disk in AB Aur: First detection of SO in a circumstellar disk
- Chemical Evolution in a Protoplanetary Disk within Planet Carved Gaps and Dust Rings
- Continuum and line modeling of disks around young stars II. Line diagnostics for GASPS from the DENT grid
- New constraints on the dust and gas distribution in the LkCa 15 disk from ALMA
- Measuring elemental abundance ratios in protoplanetary disks at millimeter wavelengths
- A deep search for H2D+ in protoplanetary disks
- Protoplanetary disks: Sensitivity of the chemical composition to various model parameters
- Dissociative photoionization of polycyclic aromatic hydrocarbon molecules carrying an ethynyl group
- A large, massive, rotating disk around an isolated young stellar object
- An Unbiased 1.3 mm Emission Line Survey of the Protoplanetary Disk Orbiting LkCa 15
- A Combined Spitzer and Herschel Infrared Study of Gas and Dust in the Circumbinary Disk Orbiting V4046 Sgr
- Recollimation boundary layers as X-ray sources in young stellar jets
- Probing UV-Sensitive Pathways for CN and HCN Formation in Protoplanetary Disks with the Hubble Space Telescope
- Physical conditions for dust grain alignment in Class 0 protostellar cores I. Observations of dust polarization and molecular irradiation tracers
- An SMA Survey of Chemistry in Disks around Herbig AeBe Stars
- HCO+ Detection of Dust-Depleted Gas in the Inner Hole of the LkCa 15 Pre-Transitional Disk
- PRODIGE -- Planet-forming disks in Taurus with NOEMA. I. Overview and first results for 12CO, 13CO, and C18O
- X-ray induced deuterium enrichment on N-rich organics in protoplanetary disks: an experimental investigation using synchrotron light
- Circumplanetary Disk Candidate in the Disk of HD 163296 Traced by Localized Emission from Simple Organics
- Molecules with ALMA at Planet-forming Scales (MAPS) VIII: CO Gap in AS 209--Gas Depletion or Chemical Processing?
- Chemical evolution of a protoplanetary disk
- Protoplanetary Disk Chemistry
- Chemistry in protoplanetary disks (short review in Russian)