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J. Weiner, D. D. S. Hale, C. H. Townes (Space Sciences Laboratory, UC Berkeley), J. H. Lacy (University of Texas)
A straight-forward measurement of the diameters of giant stars is, in general, difficult. The diffuse nature of the surrounding stellar atmosphere and the presence of spectral lines as well as circumstellar dust can cause the apparent diameters to differ substantially from the actual photospheric diameter. Using the two-telescope ISI interferometer, with its narrow band heterodyne detection system, we were able to measure stellar diameters at 11.15um, avoiding strong spectral lines and minimizing the errors due to limb darkening. In addition, the mid-infrared spectrum of these stars was observed so that any change in the measured diameter due to spectral lines could be estimated. This change, typically, will be less than 2
The author(s) of this abstract have provided an email address for comments about the abstract: johnw@ssl.berkeley.edu