| 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 | 81.52 yr (29,777 d) |
| Aphelion | 3.5198 AU |
| 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 designation 1989 AU) is a background asteroid from the central regions of the asteroid belt, approximately 17 kilometers (11 miles) in diameter. It was discovered on 4 January 1989 by Japanese astronomers Seiji Ueda and Hiroshi Kaneda at the Kushiro Observatory on Hokkaido, Japan. [1] The likely elongated asteroid has a brightness variation of 0.45 magnitude [11] and occulted a star in the constellation Cetus in November 2014. [12] It was named for the Japanese town of Yoichi. [1]
Yoichi is a non-family asteroid from the main belt's background population. [3] It orbits the Sun in the central 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 an eccentricity of 0.31 and an inclination of 8° concerning the ecliptic. [2]
The body's observation arc begins with its first observations as 1935 YH at Johannesburg Observatory in December 1935, or 53 years before its official discovery observation at Kushiro. [1]
Yoichi is an assumed S-type asteroid, while the body's albedo indicates a carbonaceous C-type asteroid (see below). [5]
In November 2015, astronomers took photometric data of Yoichi at the Oakley Southern Sky Observatory in Australia. However, no rotational lightcurve could be constructed. The asteroid's brightness amplitude was 0.42 magnitude ( U=n.a. ), indicative of an elongated shape. [11] As of 2018, the body's rotation period, pole, and shape remain unknown. [5]
According to the surveys carried out by the Infrared Astronomical Satellite IRAS, the Japanese Akari satellite, and the NEOWISE mission of NASA's Wide-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]
The Collaborative Asteroid Lightcurve Link derives an albedo of 0.0777 and a diameter of 16.54 kilometers based on an absolute magnitude of 12.3. [5]
On 2 November 2014, Yoichi occulted an 8.4 magnitude star HIP 14421 in the constellation 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 approximately 6.8 km/s . An approximate diameter of 20 kilometers was assumed for the asteroid. [12]
This minor planet was named after the Japanese town of Yoichi, Hokkaido, where the Kushiro Observatory was discovered. [1] The Minor Planet Center published the official naming citation on 4 August 2001 ( M.P.C. 43189). [13]
