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Radio Astronomy

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Author Topic: Radio Astronomy  (Read 104 times)
Jennie McGrath
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Posts: 4348

« Reply #15 on: August 16, 2007, 11:19:10 pm »

Other modern developments

Between 1950 and 1972, Robert Hanbury Brown and Richard Q. Twiss used optical intensity interferometers to measure the diameters of a large number of stars at visible wavelengths.

Impressive results were obtained in the 1990s, with the Mark III interferometer measuring diameters of 100 of stars and many accurate stellar positions and ISI measuring stars in the mid-infrared for the first time. Additional results include direct measurements of the sizes of and distances to Cepheid variable stars, and young stellar objects.

In the early 2000s single-baseline interferometry became possible with large telescopes, allowing the first measurements of extra-galactic targets. Very primitive imaging has now become technically feasible using large telescopes (using a maximum of 3 VLT telescopes with the AMBER instrument), and it is hoped that by 2008 a useful imaging capability will be available even for extragalactic sources (using e.g. 6 telescopes of the Magdalena Ridge Observatory Interferometer).

Projects are now beginning that will use interferometers to search for extrasolar planets, either by astrometric measurements of the reciprocal motion of the star (as used by the Palomar Testbed Interferometer and the VLTI) or through the use of nulling (as will be used by the Keck Interferometer and Darwin).
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