J. A. Eisner et al 2007 ApJ 654 L77 doi:10.1086/510717
J. A. Eisner1,2, J. R. Graham1, R. L. Akeson3, E. R. Ligon4, M. M. Colavita4, G. Basri1, K. Summers5, S. Ragland5 and A. Booth4
Show affiliationsUsing a new grism at the Keck Interferometer, we obtained spectrally dispersed (R ~ 230) interferometric measurements of the Mira star R Vir. These data show that the measured radius of the emission varies substantially from 2.0 to 2.4 μm. Simple models can reproduce these wavelength-dependent variations using extended molecular layers, which absorb stellar radiation and reemit it at longer wavelengths. Because we observe spectral regions with and without substantial molecular opacity, we determine the stellar photospheric radius, uncontaminated by molecular emission. We infer that most of the molecular opacity arises at approximately twice the radius of the stellar photosphere.
circumstellar matter; instrumentation: interferometers; stars: AGB and post-AGB; stars: individual (R Virginis); techniques: interferometric; techniques: spectroscopic
Issue 1 (2007 January 1)
Received 2006 October 9, accepted for publication 2006 November 8
Published 2006 December 7
J. A. Eisner et al 2007 ApJ 654 L77
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