Discovered by A. Kopff Discovered 17 October 1906 Asteroid group Asteroid belt | Discovery date 17 October 1906 Minor planet category main-belt · Vestian Orbits Sun | |
Alternative names A906 UB · 1954 SZ1958 VP · 1969 TM2 Discovery site Landessternwarte Heidelberg-Königstuhl Similar Asteroid belt, 306 Unitas, Sun, 621 Werdandi, 614 Pia | ||
1781 Van Biesbroeck, provisional designation A906 UB, is a dynamical Vestian asteroid from the inner regions of the asteroid belt, approximately 8.5 kilometers in diameter. It was discovered on 17 October 1906, by German astronomer August Kopff at Heidelberg Observatory in southern Germany.
Van Biesbroeck orbits the Sun at a distance of 2.1–2.7 AU once every 3 years and 9 months (1,353 days). Its orbit has an eccentricity of 0.11 and an inclination of 7° with respect to the ecliptic. It is not known whether the member of the Vesta family of asteroids is in fact a V/J-type, or if it is an unrelated interloper, as currently assumed to be more likely. The asteroid's observation arc begins with its official discovery observation, as no precoveries and no previous identifications were made.
According to the survey carried out by NASA's Wide-field Infrared Survey Explorer with its subsequent NEOWISE mission, Van Biesbroeck measures 8.5 kilometers in diameter, and its surface has an albedo of 0.203. A generic absolute magnitude-to-diameter conversion gives an inferred diameter between 8 and 14 kilometers, assuming an albedo in the range of 0.05 to 0.25 and an absolute magnitude of 12.8. As of 2016, Van Biesbroeck's composition, rotation period and shape remain unknown.
The minor planet was named after renowned Belgian–born observational astronomer George Van Biesbroeck, who naturalized as U.S. citizens in 1922. He specialized in the observation of double stars, variable stars, comets and asteroids, of which he discovered sixteen at the U.S. Yerkes Observatory in Williams Bay, Wisconsin, between 1922 and 1939. Naming citation was published before November 1977 (M.P.C. 3569). In 1961, he published the Van Biesbroeck's star catalog of low-mass, low-luminosity stars. The mountain Van Biesbroeck near the McDonald Observatory, the lunar crater Van Biesbroeck, and most notably the red dwarf Van Biesbroeck's Star, were also named in his honour. (There are very few stars named after people). The George Van Biesbroeck Prize, awarded by the American Astronomical Society for achievements in astronomy, also bears his name.