The Dusty AGB Star RS CrB: First Mid-Infrared Interferometric Observations with the Keck Telescopes

December 2005 • 2005ApJ...634L.169M

Authors • Mennesson, B. • Koresko, C. • Creech-Eakman, M. J. • Serabyn, E. • Colavita, M. M. • Akeson, R. • Appleby, E. • Bell, J. • Booth, A. • Crawford, S. • Dahl, W. • Fanson, J. • Felizardo, C. • Garcia, J. • Gathright, J. • Herstein, J. • Hovland, E. • Hrynevych, M. • Johansson, E. • Le Mignant, D. • Ligon, R. • Millan-Gabet, R. • Moore, J. • Neyman, C. • Palmer, D. • Panteleeva, T. • Paine, C. • Ragland, S. • Reder, L. • Rudeen, A. • Saloga, T. • Shao, M. • Smythe, R. • Summers, K. • Swain, M. • Tsubota, K. • Tyau, C. • Vasisht, G. • Wizinowich, P. • Woillez, J.

Abstract • We report interferometric observations of the semiregular variable star RS CrB, a red giant with strong silicate emission features. The data were among the first long-baseline mid-infrared stellar fringes obtained between the Keck telescopes, using parts of the new nulling beam combiner. The light was dispersed by a low-resolution spectrometer, allowing simultaneous measurement of the source visibility and intensity spectra from 8 to 12 μm. The interferometric observations allow a nonambiguous determination of the dust shell spatial scale and relative flux contribution. Using a simple spherically symmetric model, in which a geometrically thin shell surrounds the stellar photosphere, we find that ~30% to ~70% of the overall mid-infrared flux-depending on the wavelength-originates from 7-8 stellar radii. The derived shell opacity profile shows a broad peak around 11 μm (τ~=0.06), characteristic of Mg-rich silicate dust particles.

Links

• SIMBAD http://simbad.u-strasbg.fr/simbo.pl?bibcode=2005ApJ...634L.169M
• PREPRINT http://arxiv.org/abs/astro-ph/0511425
• ELECTR https://doi.org/10.1086%2F498864
• SPIRES http://inspirehep.net/search?p=find+eprint+astro-ph/0511425