| Discovery[1] | |
|---|---|
| Discovered by | A. Nakamura |
| Discovery site | Kuma Kogen Obs. |
| Discovery date | 24 February 1995 |
| Designations | |
| (8306) Shoko | |
Named after | Shoko Sawada[1] (Japanese singer) |
| 1995 DY1 · 1986 QA6 | |
| main-belt[1][2] · (inner) Flora[3][4] | |
| Orbital characteristics[2] | |
| Epoch 23 March 2018 (JD 2458200.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 31.41yr (11,474 d) |
| Aphelion | 2.7366AU |
| Perihelion | 1.7455 AU |
| 2.2411 AU | |
| Eccentricity | 0.2211 |
| 3.35 yr (1,225 d) | |
| 126.86° | |
| 0° 17m 37.68s / day | |
| Inclination | 4.7821° |
| 208.66° | |
| 143.48° | |
| Knownsatellites | 1(D:1.28 kmP:36.20 h)[5][6] |
| Physical characteristics | |
| 2.38 km(calculated)[3] 3.21 km(estimate)[5] | |
| 3.3503±0.0002 h[6] 3.604±0.002 h[7] | |
| 0.24(assumed)[3] | |
| S(assumed)[3] | |
| 14.83±0.07(R)[6] 14.9[2] 15.28[3][8] | |
8306 Shoko, provisional designation1995 DY1, is a Florianasteroid and a synchronousbinary system from the inner regions of theasteroid belt, approximately 3 kilometers (2 miles) in diameter. It was discovered on 24 February 1995, by Japanese astronomerAkimasa Nakamura at theKuma Kogen Astronomical Observatory in southern Japan, who named it after Japanese singer-songwriterShoko Sawada.[1] The likelyS-type asteroid has arotation period of 3.35 hours.[3] The discovery of its 1.3-kilometerminor-planet moon was announced in December 2013.[6]
Shoko is a member of theFlora family (402),[3][4] a giantasteroid family and the largest family of stony asteroids in the main-belt.[9] It orbits the Sun in theinner asteroid belt at a distance of 1.7–2.7 AU once every 3 years and 4 months (1,225 days;semi-major axis of 2.24 AU). Its orbit has aneccentricity of 0.22 and aninclination of 5° with respect to theecliptic.[2] The body'sobservation arc begins with its first observation as1986 QA6 at theSiding Spring Observatory in August 1986, nearly 9 years prior to its official discovery observation at Kuma Kogen.[1]
Shoko is an assumed, stonyS-type asteroid,[3] which is also the overallspectral type of the Florian asteroids.[9]: 23 It has anabsolute magnitude between 14.83 and 15.28.[2][3]
In September and October 2013, two rotationallightcurves ofShoko were obtained fromphotometric observations by astronomersPetr Pravec andDavid Polishook.[6][7] Lightcurve analysis gave a well-definedrotation period of 3.3503 and 3.604 hours with a low brightness amplitude of 0.11 and 0.10magnitude, respectively (U=3/3).[3]
TheCollaborative Asteroid Lightcurve Link assumes analbedo of 0.24 – derived from8 Flora, the parent body of the Flora family – and calculates a diameter of 2.38 kilometers based on anabsolute magnitude of 15.28,[3] while the Johnston's Archive estimates a diameter 3.21.[5]
In October 2013, photometric observations byPetr Pravec and a large international collaboration, revealed, thatShoko is an synchronousbinary asteroid with aminor-planet moon orbiting it every 36.20 hours (1.508 days) at an estimated average distance of9.4 km.[5] The discovery was announced in December 2013.[6] The mutualoccultation events suggest the presence of a satellite with a diameter1.28 km or more than 40% the size of its primary.[5] The discoverers also suspect that there might be a possible third body,[6] which would make it a raretriple asteroid. As of 2018, no follow-up observations have been conducted.[3]
Thisminor planet was named by the discoverer after Japanese singer-songwriter of ballads and pop songs,Shoko Sawada (born 1962), who has recorded a large number of studio albums since her debut in 1979.[1] The official naming citation was published by theMinor Planet Center on 10 June 1998 (M.P.C. 32095).[10]
