2007/07/20 by D. P. K. Banerjee, D. Banerjee, K. A. Misselt +4
Physics and Astronomy · #Astrophysical Phenomena and Observations #Astrophysics and Star Formation Studies #Galaxies: Formation, Evolution, Phenomena #astro-ph
paper · pdf · doi:10.1086/521528
4 pages, 2 figures in ApJ style; to be published in ApJ Letters
arxiv created 2007/07/20 · openalex publication_date 2007/08/16 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/31
We present broadband 24, 70, and 160 μm photometry and 5-35 and 55-90 μm spectra of the eruptive variable V4332 Sgr from Spitzer observations. The distinguishing feature of the 5-35 μm spectrum is an unusually broad absorption feature near 10 μm at the position generally associated with silicate-rich dust. Through radiative transfer modeling, we show that this broad feature cannot arise from silicates alone but requires the inclusion of alumina (Al 2 O 3 ) as a dust condensate. The case for including Al 2 O 3 is further strengthened by the presence of the AlO radical, a potentially important molecule in forming Al 2 O 3 . The present detection indicates that porous alumina manifests itself through a broadening of the 9.7 μm silicate feature and additionally displays, on the shoulder of the silicate feature, a component at ~11.5 μm. We discuss how further observations of V4332 Sgr may have the potential of verifying some general predictions of the dust condensation process.