HERSCHEL OBSERVATIONS OF GAS AND DUST IN THE UNUSUAL 49 Ceti DEBRIS DISK
- Exoplanets and Stellar Astrophysics Laboratory, NASA Goddard Space Flight Center, Code 667, Greenbelt, MD 20771 (United States)
- Kapteyn Astronomical Institute, University of Groningen, 9700 AV Groningen (Netherlands)
- Departamento de Astrofisica, Centro de Astrobiologia (INTA-CSIC), ESAC Campus, PO Box 78, E-28691 Villanueva de la Canada, Madrid (Spain)
- ALMA, Avda Apoquindo 3846, Piso 19, Edificio Alsacia, Las Condes, Santiago (Chile)
- Departmento Fisica Teorica, Facultad de Ciencias, Universidad Autonoma de Madrid, Cantoblanco, E-28049 Madrid (Spain)
- Department of Astronomy, University of Maryland, College Park, MD 20742 (United States)
- Max Planck Institute for Astronomy, Koenigstuhl 17, D-69117, Heidelberg (Germany)
- Konkoly Observatory of the Hungarian Academy of Sciences, P.O. Box 67, H-1525 Budapest (Hungary)
- UJF-Grenoble 1/CNRS-INSU, Institut de Planetologie et d'Astrophysique de Grenoble, UMR 5274, F-38041, Grenoble (France)
- SOFIA-USRA, NASA Ames Research Center, Building N232, PO Box 1, Moffett Field, CA 94035 (United States)
- NASA Herschel Science Center, California Institute of Technology, 1200 E. California Blvd., Mail Stop 220-6, Pasadena, CA 91125 (United States)
We present far-IR/sub-mm imaging and spectroscopy of 49 Ceti, an unusual circumstellar disk around a nearby young A1V star. The system is famous for showing the dust properties of a debris disk, but the gas properties of a low-mass protoplanetary disk. The data were acquired with the Herschel Space Observatory PACS and SPIRE instruments, largely as part of the ''Gas in Protoplanetary Systems'' (GASPS) Open Time Key Programme. Disk dust emission is detected in images at 70, 160, 250, 350, and 500 {mu}m; 49 Cet is significantly extended in the 70 {mu}m image, spatially resolving the outer dust disk for the first time. Spectra covering small wavelength ranges centered on eight atomic and molecular emission lines were obtained, including [O I] 63 {mu}m and [C II] 158 {mu}m. The C II line was detected at the 5{sigma} level-the first detection of atomic emission from the disk. No other emission lines were seen, despite the fact that the O I line is the brightest one observed in Herschel protoplanetary disk spectra. We present an estimate of the amount of circumstellar atomic gas implied by the C II emission. The new far-IR/sub-mm data fills in a large gap in the previous spectral energy distribution (SED) of 49 Cet. A simple model of the new SED confirms the two-component structure of the disk: warm inner dust and cold outer dust that produces most of the observed excess. Finally, we discuss preliminary thermochemical modeling of the 49 Cet gas/dust disk and our attempts to match several observational results simultaneously. Although we are not yet successful in doing so, our investigations shed light on the evolutionary status of the 49 Cet gas, which might not be primordial gas but rather secondary gas coming from comets.
- OSTI ID:
- 22140196
- Journal Information:
- Astrophysical Journal, Vol. 771, 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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