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A 7 micron dust emission feature in oxygen-rich circumstellar shells

1994; IOP Publishing; Volume: 430; Linguagem: Inglês

10.1086/174406

1538-4357

J. H. Goebel, J. D. Bregman, F. C. Witteborn,

Astrophysics and Star Formation Studies

view Abstract Citations (13) References (46) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS A 7 Micron Dust Emission Feature in Oxygen-rich Circumstellar Shells Goebel, J. H. ; Bregman, J. D. ; Witteborn, F. C. Abstract New 4 to 8 micron infrared spectroscopic observations of two oxygen-rich stars are presented and combined with IRAS LRS data to span the 4 to 24 micron wavelength range. In the 4 to 8 micron wavelength range, we observe a 7.15 micron (1400/cm) emission feature. The new feature at 7.15 microns is not uniquely correlated with any of the sharply defined 10, 11, 13.1, and 19.7 micron emission features that are known to be present in this class of circumstellar shells, but it does not appear to be correlated with the spectrally broad dust emission in the 10 to 20 micron spectral region. The feature has not been reported previously in any other astronomical environment. A reinterpretation of prior 4 to 8 micron spectroscopy of alpha Ori and R Cas reveals the presence of the 7.15 micron emission in alpha Ori and possibly in R Cas. The spectrally narrow 19.7 micron emission, that is distinctly diffeent than the relatively broad silicate 18 micron emmision feature in oxygen-rich dust shells, is also observed to be present in the LRS spectrum of SAO 197549. The implication of these observations is that a universal astronomical silicate does not exist in oxygen-rich circumstellar shells. This variety is analogous to that observed in interplanetary dust particles and may indicate an intimate relation between the classes of condensates. Publication: The Astrophysical Journal Pub Date: July 1994 DOI: 10.1086/174406 Bibcode: 1994ApJ...430..317G Keywords: Cosmic Dust; Infrared Astronomy; Infrared Stars; Interstellar Extinction; Oxygen; Stellar Composition; Stellar Envelopes; Stellar Spectra; Astronomical Spectroscopy; Emission Spectra; Infrared Astronomy Satellite; Spaceborne Astronomy; Astronomy; STARS: CIRCUMSTELLAR MATTER; ISM: DUST; EXTINCTION; INFRARED: STARS; STARS: INDIVIDUAL CONSTELLATION NAME: ALPHA ORIONIS; STARS: INDIVIDUAL CONSTELLATION NAME: R CASSIOPEIAE full text sources ADS | data products SIMBAD (4)