Discovered by K. Reinmuth MPC designation 2391 Tomita Observation arc 87.04 yr (31,792 days) Orbits Sun Asteroid family Nysa family | Discovery date 9 January 1957 Minor planet category main-belt · Nysa Discovered 9 January 1957 Discoverer Karl Wilhelm Reinmuth | |
Alternative names 1957 AA · 1929 VX
1938 BF · 1942 DF
1957 BA · 1977 KM
1978 PA4 · 1980 DC6 Named after Kōichirō Tomita (astronomer) Discovery site Heidelberg-Königstuhl State Observatory Similar 1862 Apollo, Sun, 1419 Danzig, 1056 Azalea, 1635 Bohrmann | ||
2391 Tomita, provisional designation 1957 AA, is a Nysian asteroid from the inner regions of the asteroid belt, approximately 10–20 kilometers in diameter. It was discovered on 9 January 1957, by German astronomer Karl Reinmuth at Heidelberg Observatory in southern Germany.
The asteroid is a member of the Nysa family, which is named after its most massive member 44 Nysa. While the Collaborative Asteroid Lightcurve Link (CALL) classifies this body as a stony S-type asteroid, it is considered to be a carbonaceous C-type asteroid by Pan-STARRS large-scale survey. It orbits the Sun at a distance of 2.1–2.8 AU once every 3 years and 10 months (1,393 days). Its orbit has an eccentricity of 0.13 and an inclination of 3° with respect to the ecliptic. The first precovery was taken at Lowell Observatory in 1929, extending the asteroid's observation arc by 28 years prior to its discovery.
According to the surveys carried out by NASA's Wide-field Infrared Survey Explorer with its subsequent NEOWISE mission, the asteroid measures between 16.6 and 19.4 kilometers in diameter and its surface has a low albedo between 0.03 and 0.07, respectively. As CALL considers the body to be of a stony composition, it assumes a much higher albedo of 0.21 and calculates a diameter of 9.2 kilometers, as the higher the asteroid's reflectivity (albedo), the shorter its diameter at a constant absolute magnitude (brightness).
In December 2013, two rotational light-curves were obtained for this asteroid from photometric observations. They gave a rotation period of 7000795330000000000♠7.9533±0.0005 and 7000843500000000000♠8.435±0.079 hours with a brightness variation of 0.14 and 0.15 in magnitude, respectively. (U=3/n.a.).
The minor planet was named in honor of Japanese astronomer Kōichirō Tomita (1925–2006), long-time observer at the Tokyo Astronomical Observatory, and a discoverer of minor planets and comets himself. Tomita was also known as one of Japan's principal popularizer of astronomy. Naming citation was published before November 1977 (M.P.C. 2391).