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The dusty AGB star RS CrB: first mid-infrared interferometric observations with the Keck Telescopes

B. Mennesson·C. Koresko·M. J. Creech-Eakman·E. Serabyn·M. M. Colavita
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Abstract

We report interferometric observations of the semi-regular 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 microns. The interferometric observations allow a non-ambiguous 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 microns (tau ~ 0.06), characteristic of Mg-rich silicate dust particles.

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B. Mennesson, C. Koresko, M. J. Creech-Eakman, E. Serabyn, M. M. Colavita. 2005-11-15. The dusty AGB star RS CrB: first mid-infrared interferometric observations with the Keck Telescopes. https://doi.org/10.1086/498864

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