A single-dish survey of the HCO+, HCN, and CN emission toward the T Tauri disk population in Taurus

Abstract

(Abridged) As the stellar X-ray and UV light penetration of a protoplanetary disk depends sensitively on the dust properties, trace molecular species like HCO+, HCN, and CN are expected to show marked differences from photoprocessing effects as the dust content in the disk evolves. We investigate the evolution of the UV irradiation of the molecular gas in a sample of classical T Tauri stars in Taurus that exhibit a wide range in grain growth and dust settling properties. We obtained HCO+ (J=3-2), HCN (J=3-2), and CN (J=2-1) observations of 13 sources with the JCMT. Our sample has 1.3mm fluxes in excess of 75mJy, indicating the presence of significant dust reservoirs; a range of dust settling as traced through their spectral slopes between 6, 13, and 25 microns; and varying degrees of grain growth as extrapolated from the strength of their 10-micron silicate emission features. We compare the emission line strengths with the sources' continuum flux and infrared features, and use detailed modeling based on two different model prescriptions to compare typical disk abundances for HCO+, HCN, and CN with the gas-line observations for our sample. We detected HCO+ (3-2) toward 6 disks, HCN (3-2) from 0 disks, and CN (2-1) toward 4 disks. For the complete sample, there is no correlation between the gas-line strengths or their ratios and either the sources' dust continuum flux or infrared slopes.

Accepted for publication in A&A, 19 pages, 13 figures

References in corpus (14)

• The Disk Population of the Taurus Star-Forming Region
• UV excess measures of accretion onto young very low-mass stars and brown dwarfs
• The XMM-Newton Extended Survey of the Taurus Molecular Cloud (XEST)
• Structure and evolution of pre-main sequence circumstellar disks
• The Taurus Spitzer Survey: New Candidate Taurus Members Selected Using Sensitive Mid-Infrared Photometry
• Gas and Dust Emission at the Outer Edge of Protoplanetary Disks
• Disks around CQ Tau and MWC 758: dense PDR or gas dispersal?
• Discovery of a bipolar X-ray jet from the T Tauri star DG Tau
• Relation between the luminosity of young stellar objects and their circumstellar environment
• Molecules in the disk orbiting the twin young suns of V4046 Sgr
• Chemistry in Disks. II. -- Poor molecular content of the AB Aur disk
• Searching for Gas-Rich Disks around T Tauri Stars in Lupus
• X-rays from young stars - a summary of highlights from the XMM-Newton Extended Survey of the Taurus Molecular Cloud (XEST)
• Molecules in the Circumstellar Disk Orbiting BP Piscium

Cited by in corpus (12)

• A sensitive survey for 13CO, CN, H2CO and SO in the disks of T Tauri and Herbig Ae stars
• CN rings in full protoplanetary disks around young stars as probes of disk structure
• Nitrogen isotope fractionation in protoplanetary disks
• Chemistry in Disks X: The Molecular Content of Proto-planetary Disks in Taurus
• Molecules with ALMA at Planet-forming Scales (MAPS) XI: CN and HCN as Tracers of Photochemistry in Disks
• Unbiased mm-wave Line Surveys of TW Hya and V4046 Sgr: The Enhanced C2H and CN Abundances of Evolved Protoplanetary Disks
• X-ray radiative transfer in protoplanetary disks - The role of dust and X-ray background fields
• The ALMA Lupus protoplanetary disk survey: evidence for compact gas disks and molecular rings from CN
• The Flared Gas Structure of the Transitional Disk around Sz 91
• Molecules in the transition disk orbiting T Cha
• An Unbiased 1.3 mm Emission Line Survey of the Protoplanetary Disk Orbiting LkCa 15
• Thermochemical modelling of brown dwarf discs