Charles H. Townes#


Professor in the Graduate School
Astrophysics Experiment

Ph.D., California Institute of Technology, 1939, Professor at Berkeley since 1967; member National Academy of Sciences; Nobel Prize in Physics, 1964.

Research Interests

I am interested in astrophysics broadly. My primary research at present involves very high angular resolution astronomy in the mid-infrared (10 micron wavelength region) by use of interferometric techniques. Three 1.65 meter telescopes mounted in trailers have been constructed so that interferometry can be carried out at various baselines. They are installed on Mt. Wilson, and are obtaining good results. The first two represented the first time that very high angular resolution was made available on a regular basis in the mid-infrared region. Construction of the third similar telescope provides three baselines simultaneously rather than our previous single one between the two telescopes, which allows two-dimensional imaging and management of asymmetries. Scientific objectives include: 1) the angular resolution, proper motions, and study of protostars or unusual stars hidden in the dust clouds of their origin; 2) angular resolution of late-type stars, the molecules and solids formed from their emissions, and their dynamics; 3) high resolution determination of where and how molecules are formed around stars; and 4) high resolution mapping of other important infrared objects.

Current Projects

Examples of our work include demonstration that old stars throw off substantial material episodically on time scales of 10-100 years, discovery of a recent episode in which Betelgeuse suddenly emitted a large amount of gas, measurement of Betelgeuse's diameter, and discovery that it is not circular. These represent the first measurement of a stellar size at mid-IR wavelengths, giving a much more reliable (and somewhat larger) size because of the non-uniform brightness in the visible region, including darkening at the edges of the star due to its atmosphere. The variable star Mira has recently been measured and shown to be appreciably larger than previously thought, as well as to throw off dust shells somewhat irregularly. We have also measured its change in size over its yearly period. We see motion of material around a number of stars. And spatial interferometry on spectral lines has been carried out. This allows study of the formation and conditions of molecular material in stellar atmospheres and surroundings.

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