Precision Measurement of Stellar Sizes and Circumstellar Material with 10 micron Interferometry and Narrow Frequency Bandwidths

University Of California-Berkeley, Berkeley CA

Investigators

Abstract

Townes, Charles " Precision Measurement of Stellar Sizes and Circumstellar Material with 10 Micron Interferometry and Narrow Frequency Bandwidths" AST- 0097994 Berkeley's unique Infrared Spatial Interferometer will be used for several types of high-resolution measurements. These include interferometric measurement of the diameters of old stars in narrow spectral regions of the mid-infrared (10 micron) region chosen to avoid spectral lines due to gases in the atmospheres of stars and to include only continuum radiation. Measurements on the spectral lines themselves can be used to determine the spatial distribution of the circumstellar gas. Recently enlarged baselines on the interferometer allow accurate measurement of stellar sizes. In particular, changes in the diameter of the brightest Mira variables can be measured and these should lead to information about departures from the sphericity of these stars. One particular advantage of working at such long wavelengths is that the uncertainties due to limb darkening are much smaller.