Creech-Eakman, M. J. and Chiang, E. I. and Joung, R. M. K. and Blake, G. A. and van Dishoeck, E. F. (2002) ISO LWS Spectra of T Tauri and Herbig AeBe stars. Astronomy and Astrophysics, 385 (2). pp. 546-562. ISSN 0004-6361. http://resolver.caltech.edu/CaltechAUTHORS:20120928-111509087
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We present an analysis of ISO-LWS spectra of eight T Tauri and Herbig AeBe young stellar objects. Some of the objects are in the embedded phase of star-formation, whereas others have cleared their environs but are still surrounded by a circumstellar disk. Fine-structure lines of [OI] and [CII] are most likely excited by far-ultraviolet photons in the circumstellar environment rather than high-velocity outflows, based on comparisons of observed line strengths with predictions of photon-dominated and shock chemistry models. A subset of our stars and their ISO spectra are adequately explained by models constructed by Chiang & Goldreich (1997) and Chiang et al. (2001) of isolated, passively heated, flared circumstellar disks. For these sources, the bulk of the LWS flux at wavelengths longward of 55 µm arises from the disk interior which is heated diffusively by reprocessed radiation from the disk surface. At 45 µm, water ice emission bands appear in spectra of two of the coolest stars, and are thought to arise from icy grains irradiated by central starlight in optically thin disk surface layers.
|Additional Information:||© 2002 ESO. Received 29 August 2001; Accepted 24 January 2002. Based in part on observations with ISO, an ESA project with instruments funded by ESA Member States (especially the PI countries: France, Germany, The Netherlands, and the United Kingdom) and with participation of ISAS and NASA. We would like to graciously acknowledge the ESA, NASA and the ISO-LWS instrument team and reduction software groups in Vilspa and Pasadena for all their work and generous support of the ISO Mission. M.J.C-E. in particular gratefully acknowledges the assistance of T. Lim, S. Molinari and S. Lord in reduction and quality control of the ISO data. We would also like to thank T. Prusti for useful and insightful comments, particularly with regard to the background contributions to the dataset. G.A.B. acknowledges support from the ISO block grant program and NASA grant NAG5-4303. E.F.vD. acknowledges support from NWO grant 614.41.003. E.I.C. acknowledges support from NASA through grant NAG5-7008 and a Hubble Fellowship grant awarded by the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., for NASA under contract NAS 5-26555. We also wish to thank M. van den Ancker, R. Waters, J. Bouwman and D. Lorenzetti for useful discussions and communicating their results prior to publication. We have made use of the COBE and IRAS databases maintained through GSFC and IPAC at Caltech as part of this study. We have also made use of the SIMBAD database created and maintained by the CDS, Strasbourg and ADS Abstract Service created and maintained by the CFA, Harvard in preparation of this manuscript.|
|Subject Keywords:||stars: pre-main sequence - infrared: stars - line: identification - stars: formation|
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|Deposited By:||Tony Diaz|
|Deposited On:||28 Sep 2012 18:39|
|Last Modified:||27 Dec 2012 02:45|
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