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تسجيل

Intensity interferometry

المؤلف:  James Binney and Michael Merrifield

المصدر:  GALACTIC ASTRONOMY

الجزء والصفحة:  p-83

2026-09-08

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Brown & Twiss (1956) developed a new interferometric technique that exploits the fact that the fluctuations in the intensities of the signals received from a star by two instruments separated by distance D are correlated in a way that depends on D and the angular diameter of the star. In intensity interferometry, phase coherence is not required, and it becomes possible to use separate telescopes and large baselines (Brown 1968). An interferometer consisting of two 6.5 m mosaic "light-buckets" separated by baselines of length 10 to 190 m operated for several years at Narrabri, Australia, and produced angular-diameter measurements for about thirty stars (Brown et al. 1974b, Brown et al. 1974a).

Angular diameters as small as 0.5 mas have been measured with this technique. However, the method is restricted to hot stars, which (with the Narrabri interferometer) must be brighter than V  2.5. The list of such stars observable from the southern hemisphere has already been exhausted, and new results will emerge only from northern-hemisphere observations, or from the use of a larger instrument that will reach fainter stars.