2478 Tokai
Stony Florian asteroid and binary system
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2478 Tokai, provisionally designated 1981 JC, is a stony Florian asteroid and binary system from the inner regions of the asteroid belt, approximately 10 kilometers in diameter. It was discovered on 4 May 1981, by Japanese astronomer Toshimasa Furuta at Tōkai Observatory (879), Japan.[14] The asteroid was named after the city of Tōkai.[2]
| Discovery[1] | |
|---|---|
| Discovered by | T. Furuta |
| Discovery site | Tōkai Obs. (879) |
| Discovery date | 4 May 1981 |
| Designations | |
| Pronunciation | /ˈtoʊkaɪ/ Japanese: [toːkai] |
Named after | Tōkai (Japanese city)[2] |
| 1981 JC · 1931 HH 1932 SE · 1934 ED 1939 VH · 1951 JP 1955 OE · 1955 QV 1957 BD · 1972 RS 1978 NU2 · 1979 XR 1981 JT | |
| main-belt · Flora[3] | |
| Orbital characteristics[1] | |
| Epoch 4 September 2017 (JD 2458000.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 84.68 yr (30,929 days) |
| Aphelion | 2.3781 AU |
| Perihelion | 2.0740 AU |
| 2.2261 AU | |
| Eccentricity | 0.0683 |
| 3.32 yr (1,213 days) | |
| 103.28° | |
| 0° 17m 48.48s / day | |
| Inclination | 4.1389° |
| 228.80° | |
| 233.85° | |
| Known satellites | 1[3][4][5] |
| Physical characteristics | |
| Dimensions | 9.238±0.112 km[6] 9.36±1.51 km[7] 9.71±0.49 km[8] 9.982±0.031 km[9] 10.087 km[10] 10.09 km (taken)[3] |
| 25.88±0.01 h[a] 25.885±0.007 h[11] 25.8913 h[b] 25.97±0.11 h[12] | |
| 0.144±0.015[8] 0.1957[10] 0.2084±0.0371[9] 0.252±0.045[6] 0.33±0.20[7] | |
| SMASS = S[1] · S[3] | |
| 11.88±0.03 (R)[b] · 12.00[7] · 12.15±0.04[13] · 12.2[1] · 12.33[9] · 12.37±0.058[3][10] · 12.80[8] | |
Orbit and classification
Tokai is a member of the Flora family, one of the largest groups of stony asteroids in the main-belt. It orbits the Sun in the inner main-belt at a distance of 2.1–2.4 AU once every 3 years and 4 months (1,213 days). Its orbit has an eccentricity of 0.07 and an inclination of 4° with respect to the ecliptic.[1]
Physical characteristics
In the SMASS classification, Tokai is a common S-type asteroid.[1]
Diameter and albedo
According to the surveys carried out by the Japanese Akari satellite, and NASA's Wide-field Infrared Survey Explorer (WISE) with its subsequent NEOWISE mission, Tokai measures between 9.238 and 9.982 kilometers in diameter and its surface has an albedo between 0.144 and 0.33.[6][7][8][9] The Collaborative Asteroid Lightcurve Link agrees with Petr Pravec's revised WISE-data, that is, an albedo of 0.1957 and a diameter of 10.09 kilometers with an absolute magnitude of 12.37.[3]
Satellite
Photometric observations in 2007, revealed a minor-planet moon in orbit of Tokai. It measures approximately 6 kilometers in diameter (lower limit diameter ratio of 0.72) and has an orbital period of 25.88 hours.[3][4][5]
Naming
This minor planet was named after the city of Tōkai, Japan, where the discoverer lives and the discovering observatory is located.[2] The approved naming citation was published by the Minor Planet Center on 8 February 1982 (M.P.C. 6650).[15]
Notes
- Oey (2011) web: rotation period 25.88 hours with a brightness amplitude of mag. Summary figures for (2478) Tokai at Collaborative Asteroid Lightcurve Link (CALL)
- Pravec (2007) web: rotation period 25.8913 hours with a brightness amplitude of 0.41 mag. Q=3. Summary figures for (2478) Tokai at Collaborative Asteroid Lightcurve Link (CALL)
