First Surface-resolved Results with the Infrared Optical Telescope Array Imaging Interferometer: Detection of Asymmetries in Asymptotic Giant Branch Stars

S. Ragland, W. A. Traub, J.-P. Berger, W. C. Danchi, J. D. Monnier, L. A. Willson, N. P. Carleton, M. G. Lacasse, R. Millan-Gabet, E. Pedretti, F. P. Schloerb, W. D. Cotton, C. H. Townes, M. Brewer, P. Haguenauer, P. Kern, P. Labeye, F. Malbet, D. Malin, M. Pearlman & 3 others K. Perraut, K. Souccar, G. Wallace

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Abstract

We have measured nonzero closure phases for about 29% of our sample of 56 nearby asymptotic giant branch (AGB) stars, using the three-telescope Infrared Optical Telescope Array (IOTA) interferometer at near-infrared wavelengths (H band) and with angular resolutions in the range 5-10 mas. These nonzero closure phases can only be generated by asymmetric brightness distributions of the target stars or their surroundings. We discuss how these results were obtained and how they might be interpreted in terms of structures on or near the target stars. We also report measured angular sizes and hypothesize that most Mira stars would show detectable asymmetry if observed with adequate angular resolution.
Original languageEnglish
Pages (from-to)650-660
Number of pages11
JournalThe Astrophysical Journal
Volume652
Issue number1
Publication statusPublished - 1 Nov 2006

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Ragland, S., Traub, W. A., Berger, J-P., Danchi, W. C., Monnier, J. D., Willson, L. A., ... Wallace, G. (2006). First Surface-resolved Results with the Infrared Optical Telescope Array Imaging Interferometer: Detection of Asymmetries in Asymptotic Giant Branch Stars. The Astrophysical Journal, 652(1), 650-660.