Sensitive survey for 13CO, CN, H2CO, and SO in the disks of T Tauri and Herbig Ae stars II: Stars in $\rho$ Oph and upper Scorpius

Abstract

We attempt to determine the molecular composition of disks around young low-mass stars in the $\rho$ Oph region and to compare our results with a similar study performed in the Taurus-Auriga region. We used the IRAM 30 m telescope to perform a sensitive search for CN N=2-1 in 29 T Tauri stars located in the $\rho$ Oph and upper Scorpius regions. ${}^{13}$CO J=2-1 is observed simultaneously to provide an indication of the level of confusion with the surrounding molecular cloud. The bandpass also contains two transitions of ortho-H${}_2$CO, one of SO, and the C${}^{17}$O J=2-1 line, which provides complementary information on the nature of the emission. Contamination by molecular cloud in ${}^{13}$CO and even C${}^{17}$O is ubiquitous. The CN detection rate appears to be lower than for the Taurus region, with only four sources being detected (three are attributable to disks). H${}_2$CO emission is found more frequently, but appears in general to be due to the surrounding cloud. The weaker emission than in Taurus may suggest that the average disk size in the $\rho$ Oph region is smaller than in the Taurus cloud. Chemical modeling shows that the somewhat higher expected disk temperatures in $\rho$ Oph play a direct role in decreasing the CN abundance. Warmer dust temperatures contribute to convert CN into less volatile forms. In such a young region, CN is no longer a simple, sensitive tracer of disks, and observations with other tracers and at high enough resolution with ALMA are required to probe the gas disk population.

arXiv comment18 pages, 5 figures, accepted for publication in A&A

References in corpus (22)

• Embedded Clusters in Molecular Clouds
• A Census of the Young Cluster IC 348
• Protoplanetary Disk Structures in Ophiuchus II: Extension to Fainter Sources
• A dual-frequency sub-arcsecond study of proto-planetary disks at mm wavelengths: First evidence for radial variations of the dust properties
• ISOCAM observations of the rho Ophiuchi cloud: Luminosity and mass functions of the pre-main sequence embedded cluster
• A Parametric Modeling Approach to Measuring the Gas Masses of Circumstellar Disks
• Low-Mass Star Formation and the Initial Mass Function in the Rho Ophiuchi Cloud Core
• Dust grain growth in rho-Ophiuchi protoplanetary disks
• Chemistry in Disks. IV. Benchmarking gas-grain chemical models with surface reactions
• Ices in the edge-on disk CRBR 2422.8-3423: Spitzer spectroscopy and Monte Carlo radiative transfer modeling
• Disk Imaging Survey of Chemistry with SMA: II. Southern Sky Protoplanetary Disk Data and Full Sample Statistics
• ALMA Observations of the Orion Proplyds
• A sensitive survey for 13CO, CN, H2CO and SO in the disks of T Tauri and Herbig Ae stars
• Molecular ions in the protostellar shock L1157-B1
• Cold CO in circumstellar disks: On the effects of photodesorption and vertical mixing
• Single peaked CO emission line profiles from the inner regions of protoplanetary disks
• CO J=6-5 observations of TW Hya with the SMA
• HST/NICMOS Imaging Survey of the Ophiuchus (Lynds 1688) Cluster
• Chemistry in Disks. V: CN and HCN in proto-planetary disks
• Grain Surface Reactions in Molecular Clouds: The Effect of Cosmic Rays and Quantum Tunneling
• Spatial study with the VLT of a new resolved edge-on circumstellar dust disk discovered at the periphery of the rho Ophiuchi dark cloud
• VLBA determinations of the distances to nearby star-forming regions

Cited by in corpus (15)

• ALMA Observations of Circumstellar Disks in the Upper Scorpius OB Association
• The many-faceted light curves of young disk-bearing stars in Upper Sco and $\rho$ Oph observed by $K2$ Campaign 2
• Chemistry in Disks X: The Molecular Content of Proto-planetary Disks in Taurus
• A high binary fraction for the most massive close-in giant planets and brown dwarf desert members
• The Flying Saucer: Tomography of the thermal and density gas structure of an edge-on protoplanetary disk
• Dynamical Masses of Low Mass Stars in the Taurus and Ophiuchus Star Forming Regions
• The hybrid disks: a search and study to better understand evolution of disks
• The shadow of the Flying Saucer: A very low temperature for large dust grains
• The ALMA Lupus protoplanetary disk survey: evidence for compact gas disks and molecular rings from CN
• Sulfur-Bearing Species Tracing the Disk/Envelope System in the Class I Protostellar Source Elias 29
• An ALMA Survey of Chemistry in Disks around M4-M5 Stars
• Vertically extended and asymmetric CN emission in the Elias 2-27 protoplanetary disk
• Ionization-Driven Depletion and Redistribution of CO in Protoplanetary Disks
• Tracing Molecular Stratification within an Edge-on Protoplanetary Disk
• A multiwavelength analysis of the spiral arms in the protoplanetary disk around WaOph 6