A CO survey in planet-forming disks: Characterizing the gas content in the epoch of planet formation
- Atacama Large Millimeter/Submillimeter Array, Joint ALMA Observatory, Alonso de Córdova 3107, Vitacura 763-0355 Santiago (Chile)
- Department of Astrophysics, Centre for Astrobiology (CAB, CSIC-INTA), ESAC Campus, P.O. Box 78, E-28691 Villanueva de la Cañada, Madrid (Spain)
- Departamento de Astronomía, Universidad de Chile, Camino El Observatorio 1515, Las Condes, Santiago (Chile)
- UMI-FCA, CNRS/INSU, France (UMI 3386) (France)
- Departamento de Física Teórica, Facultad de Ciencias, Universidad Autónoma de Madrid, Cantoblanco, E-28049 Madrid (Spain)
- Department of Astronomy, University of California, Berkeley, CA 94720 (United States)
- Institut de Ciéncies de l'Espai (CSIC-IEEC), Campus UAB-Facultat de Ciéncies, Torre C5-parell 2, E-08193 Bellaterra, Catalunya (Spain)
- Institut de Ciències de l'Espai (CSIC-IEEC) and Institut de Ciències del Cosmos (UB-IEEC), Martí i Franquès 1, E-08028 Barcelona (Spain)
We carried out a {sup 12}CO(3-2) survey of 52 southern stars with a wide range of IR excesses (L {sub IR}/L {sub *}) using the single-dish telescopes APEX and ASTE. The main aims were (1) to characterize the evolution of molecular gas in circumstellar disks using L {sub IR}/L {sub *} values as a proxy of disk dust evolution, and (2) to identify new gas-rich disk systems suitable for detailed study with ALMA. About 60% of the sample (31 systems) have L {sub IR}/L {sub *} > 0.01, typical of T Tauri or Herbig AeBe stars, and the rest (21 systems) have L {sub IR}/L {sub *} < 0.01, typical of debris disks. We detect CO(3-2) emission from 20 systems, and 18 (90%) of these have L {sub IR}/L {sub *} > 0.01. However, the spectra of only four of the newly detected systems appear free of contamination from background or foreground emission from molecular clouds. These include the early-type stars HD 104237 (A4/5V, 116 pc) and HD 98922 (A2 III, 507 pc, as determined in this work), where our observations reveal the presence of CO-rich circumstellar disks for the first time. Of the other detected sources, many could harbor gaseous circumstellar disks, but our data are inconclusive. For these two newly discovered gas-rich disks, we present radiative transfer models that simultaneously reproduce their spectral energy distributions and the {sup 12}CO(3-2) line profiles. For both of these systems, the data are fit well by geometrically flat disks, placing them in the small class of non-flaring disks with significant molecular gas reservoirs.
- OSTI ID:
- 22342265
- Journal Information:
- Astronomical Journal (New York, N.Y. Online), Vol. 148, Issue 3; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 1538-3881
- Country of Publication:
- United States
- Language:
- English
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