2391 Tomita
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| Discovery[1] | |
|---|---|
| Discovered by | K. Reinmuth |
| Discovery site | Heidelberg Obs. |
| Discovery date | 9 January 1957 |
| Designations | |
| (2391) Tomita | |
Named after | Kōichirō Tomita (Japanese astronomer)[2] |
| 1957 AA · 1929 VX 1938 BF · 1942 DF 1957 BA · 1977 KM 1978 PA4 · 1980 DC6 | |
| main-belt · Nysa[3] | |
| Orbital characteristics[1] | |
| Epoch 4 September 2017 (JD 2458000.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 87.07 yr (31,804 days) |
| Aphelion | 2.7676 AU |
| Perihelion | 2.1141 AU |
| 2.4408 AU | |
| Eccentricity | 0.1339 |
| 3.81 yr (1,393 days) | |
| 345.07° | |
| 0° 15m 30.6s / day | |
| Inclination | 3.0111° |
| 163.32° | |
| 282.65° | |
| Physical characteristics | |
| Dimensions | 9.17 km (calculated)[3] 15.07±4.33 km[4] 15.20±3.74 km[5] 16.62±0.23 km[6] 17.941±0.129[7] 19.412±0.175 km[8] |
| 7.9533±0.0005 h[a] 8.435±0.079 h[b] | |
| 0.0321±0.0044[8] 0.06±0.03[5] 0.070±0.004[6] 0.07±0.07[4][7] 0.21 (assumed)[3] | |
| S[3] · C[9] | |
| 12.4[4][6][8] · 12.5[1][3] · 12.66[5] · 12.74±0.28[9] | |
2391 Tomita, provisional designation 1957 AA, is a Nysian asteroid from the inner regions of the asteroid belt, approximately 15 kilometers in diameter. The asteroid was discovered on 9 January 1957, by German astronomer Karl Reinmuth at Heidelberg Observatory in southern Germany.[10] It was named after Japanese astronomer Kōichirō Tomita.[2]
Tomita is a member of the Nysa family, which is named after its most massive member 44 Nysa. It orbits the Sun in the inner main-belt 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.[1]
A first precovery was taken at Lowell Observatory in 1929, extending the body's observation arc by 28 years prior to its official discovery observation at Heidelberg.[10]
Physical characteristics
Tomita has been characterized as a stony S-type asteroid by the Collaborative Asteroid Lightcurve Link (CALL), and as a carbonaceous C-type asteroid by Pan-STARRS' photometric survey.[3][9]
Diameter and albedo
According to the surveys carried out by NASA's Wide-field Infrared Survey Explorer with its subsequent NEOWISE mission, the asteroid measures between 15.07 and 19.4 kilometers in diameter and its surface has a low albedo between 0.03 and 0.07, respectively.[4][5][6][7][8]
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).[3]
Rotation period
In December 2013, two rotational lightcurves were obtained for this asteroid from photometric observations. They gave a rotation period of 7.9533±0.0005 and 8.435±0.079 hours with a brightness variation of 0.14 and 0.15 in magnitude, respectively. (U=3/n.a.).[a][b]
Naming
This 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.[2] The official naming citation was published by the Minor Planet Center on 14 April 1987 (M.P.C. 11748).[11]
