Stellar Interferometer

stellar interferometer

[′stel·ər ‚in·tər·fə′räm·əd·ər]
(optics)
An optical interferometer for measuring angular diameters of stars; it is attached to a telescope and measures interference rings at the telescope's focus.

Interferometer, Stellar

 

an astronomical optical instrument for the measurement of extremely small angular separations (tenths or hundredths of a second of arc) by using the phenomenon of interference of light. It is principally used to measure the angular separation between the components of close binary stars (components that are close in brightness) and the angular diameters of stars.

A distinction is made between simple and periscopic stellar interferometers. The first is an ordinary telescope with an opaque screen placed on the objective; the screen has two openings that are identical in form, for example, parallel slits. In this case interference fringes are observed on a star’s image; their appearance changes as the distance between the openings in the screen is changed and, in the case of binary stars, as a result of the mutual orientations of the line joining the components of the binary star and the openings in the screen. The simple stellar interferometer permits the resolving power of a telescope to be approximately doubled.

In the periscopic stellar interferometer, proposed by A. A. Michelson (USA), an optical system of two pairs of plane mirrors is mounted in front of the telescope’s objective, permitting two widely separated light rays from the source being measured to be directed into the telescope’s objective. This system increases the resolving power of the telescope in proportion to the distance between the outer mirrors. The angular diameters of several stars were measured for the first time in 1920–21 with the help of a periscopic stellar interferometer.

REFERENCE

Martynov, D. la. Kurs prakticheskoi astrofiziki, 2nd ed. Moscow, 1967.

E. S. KULAGIN

References in periodicals archive ?
Sirius's Diameter "A novel type of stellar interferometer has been tested by successful measurement of the angular diameter of the star Sirius....
In November 1986 the Australian governmentgranted $500,000 to the University of Sydney for construction of a stellar interferometer with a 640-meter baseline (distance between receivers).
To understand how a stellar interferometer works, imagine a wave of light coming from a star.
German-American physicist Albert Michelson and American astronomer Francis Pease begin constructing a stellar interferometer with a 6-meter (20-foot) beam to be mounted to the front of the Mount Wilson 100-inch telescope.
Michelson led to the stellar interferometer that was mounted on the 100-inch Mount Wilson reflector and used in 1920 for the first true measurements of star diameters.