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Maria
and Eric Muhlmann Award
Harold A. McAlister
Georgia State University & the CHARA Array Project
Although
optical astronomers operate at wavelengths four to five orders of
magnitude shorter than those used by radio astronomers, and although
the diameters of optical telescopes are approaching those of some
radio telescopes, the highest resolution available to astronomers
has generally been in the radio regime. The reason is simple: radio
astronomers can use the technique of interferometry, combining signals
received from several reflectors to produce images with a resolution
set by the size of the array of reflectors, not the aperture of
an individual one.
Optical
astronomers are making rapid strides in introducing interferometric
techniques to the near infrared and optical. A leader in this effort
is Harold McAlister, this year's recipient of the Maria and Eric
Muhlmann Award presented each year for "significant observational
results made possible by innovative advances in astronomical instrumentation."
Harold McAlister led the Center for High Angular Resolution Astronomy
(CHARA) team that designed, built and is now operating an array
of 1-meter telescopes that form the most powerful optical interferometer
now available. This has helped bring milli-arcsec resolution to
optical astronomy, rivaling the best resolutions obtainable at radio
wavelengths. The CHARA array has directly measured the diameters
not just of giant and supergiant stars but also of much smaller
M dwarfs. It has also enabled astronomers to measures the shapes
of both rotationally distorted stars and close binary systems, leading
to accurate stellar masses. These same interferometric techniques
will form the basis of advanced, satellite missions to study planets
orbiting other stars.
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