| Discovery[1] | |
|---|---|
| Discovered by | S. Ueda H. Kaneda |
| Discovery site | Kushiro Obs. |
| Discovery date | 4 January 1989 |
| Designations | |
| (5176) Yoichi | |
Named after | Yoichi[1](Japanese town) |
| 1989 AU · 1935 YH 1948 VS · 1948 WS 1952 OH1 · 1961 TK1 | |
| main-belt[1][2] · (middle) background[3] | |
| Orbital characteristics[2] | |
| Epoch 23 March 2018 (JD 2458200.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 81.52yr (29,777 d) |
| Aphelion | 3.5198AU |
| Perihelion | 1.8546 AU |
| 2.6872 AU | |
| Eccentricity | 0.3098 |
| 4.41 yr (1,609 d) | |
| 295.85° | |
| 0° 13m 25.32s / day | |
| Inclination | 7.7043° |
| 93.615° | |
| 269.81° | |
| Physical characteristics | |
| 15.68±1.57 km[4] 16.54 km(derived)[5] 16.56±0.7 km[6] 16.74±4.79 km[7] 18.92±5.20 km[8] 19.49±1.15 km[9] | |
| 0.05±0.03[7] 0.054±0.048[8] 0.06±0.03[4] 0.061±0.008[9] 0.0777(derived)[5] 0.0849±0.007[6] | |
| S(assumed)[5] | |
| 12.20[7][9] 12.3[2][5] 12.36±0.26[10] 12.40[8] 12.57[4] | |
5176 Yoichi (provisional designation1989 AU) is a backgroundasteroid from the central regions of theasteroid belt, approximately 17 kilometers (11 miles) in diameter. It was discovered on 4 January 1989 by Japanese astronomersSeiji Ueda andHiroshi Kaneda at theKushiro Observatory on Hokkaido, Japan.[1] The likely elongated asteroid has a brightness variation of 0.45magnitude[11] andocculted a star in the constellationCetus in November 2014.[12] It was named for the Japanese town ofYoichi.[1]
Yoichi is a non-family asteroid from the main belt'sbackground population.[3] It orbits the Sun in thecentral main-belt at a distance of 1.9–3.5 AU once every 4 years and 5 months (1,609 days;semi-major axis of 2.69 AU). Its orbit has aneccentricity of 0.31 and aninclination of 8° concerning theecliptic.[2]
The body'sobservation arc begins with its first observations as1935 YH atJohannesburg Observatory in December 1935, or 53 years before its official discovery observation at Kushiro.[1]
Yoichi is an assumedS-type asteroid, while the body'salbedo indicates a carbonaceousC-type asteroid(see below).[5]
In November 2015, astronomers tookphotometric data of Yoichi at theOakley Southern Sky Observatory in Australia. However, no rotationallightcurve could be constructed. The asteroid's brightness amplitude was 0.42magnitude (U=n.a.), indicative of an elongated shape.[11] As of 2018, the body'srotation period,pole, and shape remain unknown.[5]
According to the surveys carried out by the Infrared Astronomical SatelliteIRAS, the JapaneseAkari satellite, and theNEOWISE mission of NASA'sWide-field Infrared Survey Explorer, Yoichi measures between 15.68 and 19.49 kilometers in diameter, and its surface has an albedo between 0.05 and 0.0849.[4][6][7][8][9]
TheCollaborative Asteroid Lightcurve Link derives an albedo of 0.0777 and a diameter of 16.54 kilometers based on anabsolute magnitude of 12.3.[5]
On 2 November 2014, Yoichiocculted an 8.4 magnitude starHIP 14421 in theconstellation Cetus, causing a magnitude drop from 8.4 to 14.1 during 2.8 seconds. The occultation was visible over Southern Japan, Eastern China, and Southern California to North Florida. The asteroid's 23-kilometer-wide shadow had a speed of approximately6.8 km/s. An approximate diameter of 20 kilometers was assumed for the asteroid.[12]
Thisminor planet was named after the Japanese town ofYoichi,Hokkaido, where theKushiro Observatory was discovered.[1] TheMinor Planet Center published the official naming citation on 4 August 2001 (M.P.C. 43189).[13]
