1 August 1990 Visibility curves at 10 um wavelength for stars with dust shells
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Abstract
With the Infrared Spatial Interferometer, a two-element heterodyne interferometer operating at Mt. Wilson, California, in the atmospheric window near 10 microns, a total of 19 infrared sources have been observed. Visibility curves of about 5 percent fractional accuracy and a preliminary analysis of the data for the late-type stars Alpha Orionis, IRC + 10216, and O micron Ceti. For IRC + 10216, the data imply that the dust must be closer to the star (not farther than 2.5 stellar radii) and hotter (about 1400 K) than previously thought. Also observed are changes as large as about 60 percent in the visibility of IRC + 10216 with the phase of the stellar pulsation cycle, which imply that, as the star cools, the dust at larger radii cools off and could be as close to the star as about 1.7 stellar radii. The optical depth of the dust at 11 microns must be close to unity. The data for Omicron Ceti show similar behavior implying the presence of dust also at approximately 2.5 stellar radii and as hot as 1770 K, with an optical depth of 0.05. The visibility curve for Alpha Orionis is much simpler and is consistent with the 63 percent of the flux coming from the star, with very little dust inside a radius of 0.8 arcsec.
© (1990) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
William C. Danchi, Manfred Bester, Cuno G. Degiacomi, Peter R. McCullough, Charles H. Townes, "Visibility curves at 10 um wavelength for stars with dust shells", Proc. SPIE 1237, Amplitude and Intensity Spatial Interferometry, (1 August 1990); doi: 10.1117/12.19344; https://doi.org/10.1117/12.19344
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