CHEMISTRY IN DISKS. VII. FIRST DETECTION OF HC{sub 3}N IN PROTOPLANETARY DISKS
- Institute of Astronomy and Astrophysics, Academia Sinica, P.O. Box 23-141, Taipei 106, Taiwan (China)
- LAB, Universite de Bordeaux, UMR 5804, 2 rue de l'observatoire, F-33270 Floirac (France)
Molecular line emission from protoplanetary disks is a powerful tool to constrain their physical and chemical structure. Nevertheless, only a few molecules have been detected in disks so far. We take advantage of the enhanced capabilities of the IRAM 30 m telescope by using the new broadband correlator (fast Fourier Transform Spectrometer) to search for so far undetected molecules in the protoplanetary disks surrounding the T Tauri stars DM Tau, GO Tau, LkCa 15, and the Herbig Ae star MWC 480. We report the first detection of HC{sub 3}N at 5{sigma} in the GO Tau and MWC 480 disks with the IRAM 30 m, and in the LkCa 15 disk (5{sigma}), using the IRAM array, with derived column densities of the order of 10{sup 12} cm{sup -2}. We also obtain stringent upper limits on CCS (N < 1.5 Multiplication-Sign 10{sup 12} cm{sup -3}). We discuss the observational results by comparing them to column densities derived from existing chemical disk models (computed using the chemical code Nautilus) and based on previous nitrogen- and sulfur-bearing molecule observations. The observed column densities of HC{sub 3}N are typically two orders of magnitude lower than the existing predictions and appear to be lower in the presence of strong UV flux, suggesting that the molecular chemistry is sensitive to the UV penetration through the disk. The CCS upper limits reinforce our model with low elemental abundance of sulfur derived from other sulfur-bearing molecules (CS, H{sub 2}S, and SO).
- OSTI ID:
- 22092463
- Journal Information:
- Astrophysical Journal, Vol. 756, Issue 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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