A SOFIA FORCAST Grism Study of the Mineralogy of Dust in the Winds of Proto-planetary Nebulae: RV Tauri Stars and SRd Variables
- Minnesota Institute for Astrophysics, School of Physics and Astronomy, University of Minnesota, 106 Pleasant Street S.E., Minneapolis, MN 55455 (United States)
- USRA-SOFIA Science Center, NASA Ames Research Center, Moffett Field, CA 94035 (United States)
- Astrophysics Group, Lennard Jones Laboratory, Keele University, Keele, Staffordshire ST5 5BG (United Kingdom)
- Department of Physics and Astronomy, 264 Center for Natural Sciences, Ithaca College, Ithaca, NY 14850 (United States)
- National Optical Astronomy Observatory, P.O. Box 26732, Tucson, AZ 85726 (United States)
- Department of Physics and Astronomy, University of California, Los Angeles, CA 90095 (United States)
- Institute for Astrophysics (IfA), University of Vienna, Türkenschanzstrasse 17, A-1180 Vienna (Austria)
- Solar System Exploration Branch, Space Department, Johns Hopkins University Applied Physics Laboratory, Laurel, MD 20723 (United States)
- Astronomical Institute of the Romanian Academy, Str. Cutitul de Argint 5, Bucharest, 040557 (Romania)
We present a SOFIA FORCAST grism spectroscopic survey to examine the mineralogy of the circumstellar dust in a sample of post-asymptotic giant branch (post-AGB) yellow supergiants that are believed to be the precursors of planetary nebulae. Our mineralogical model of each star indicates the presence of both carbon-rich and oxygen-rich dust species—contrary to simple dredge-up models—with a majority of the dust in the form of amorphous carbon and graphite. The oxygen-rich dust is primarily in the form of amorphous silicates. The spectra do not exhibit any prominent crystalline silicate emission features. For most of the systems, our analysis suggests that the grains are relatively large and have undergone significant processing, supporting the hypothesis that the dust is confined to a Keplerian disk and that we are viewing the heavily processed, central regions of the disk from a nearly face-on orientation. These results help to determine the physical properties of the post-AGB circumstellar environment and to constrain models of post-AGB mass loss and planetary nebula formation.
- OSTI ID:
- 22663438
- Journal Information:
- Astrophysical Journal, Vol. 843, 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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