| Discovery[1] | |
|---|---|
| Discovered by | K. Endate K. Watanabe |
| Discovery site | Kitami Obs. |
| Discovery date | 16 May 1990 |
| Designations | |
| (4585) Ainonai | |
Named after | Ainonai, nearKitami (Japanese town)[2] |
| 1990 KQ · 1972 LU 1978 WL12 · 1981 LC | |
| Orbital characteristics[3] | |
| Epoch 31 May 2020 (JD 2459000.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 47.87yr (17,486 d) |
| Aphelion | 3.3818AU |
| Perihelion | 2.0894 AU |
| 2.7356 AU | |
| Eccentricity | 0.2362 |
| 4.52 yr (1,653 d) | |
| 220.84° | |
| 0° 13m 4.08s / day | |
| Inclination | 10.549° |
| 82.966° | |
| 184.23° | |
| Physical characteristics | |
| 10.920±0.122 km[7] | |
| 38.31±0.05 h[8] | |
| 0.112±0.011[7] | |
| C(family-based)[9][10] | |
4585 Ainonai (prov. designation:1990 KQ) is a darkChloris asteroid, approximately 11 kilometers (6.8 miles) in diameter, located in the central region of theasteroid belt. It was discovered on 16 May 1990, by Japanese amateur astronomersKin Endate andKazuro Watanabe at theKitami Observatory in eastern Hokkaidō, Japan.[1] The presumed carbonaceousC-type asteroid has a longer than averagerotation period of 38.3 hours. It was named for the Japanese town of Ainonai, located near the discovering observatory.[2]
When applying thehierarchical clustering method to itsproper orbital elements,Ainonai is a core member of theChloris family (509),[4][5][6] a smallerfamily of carbonaceous main-belt asteroids, named after its parent body410 Chloris.[10] It orbits the Sun in thecentral asteroid belt at a distance of 2.1–3.4 AU once every 4 years and 6 months (1,653 days;semi-major axis of 2.74 AU). Its orbit has aneccentricity of 0.24 and aninclination of 11° with respect to theecliptic.[3] The body'sobservation arc begins with its first observation as1972 LU atCrimea–Nauchnij on 9 June 1972, or 18 years prior to its official discovery observation at Kitami.[1]
Thisminor planet was named after Ainonai, a small Japanese town located nearKitami in easternHokkaidō. Asteroids3785 Kitami and3720 Hokkaido are named after these two places.[2] Theofficial naming citation was published by theMinor Planet Center on 21 November 1991 (M.P.C. 19338).[11]
Ainonai is an assumed carbonaceousC-type asteroid.[9] This agrees with the overallspectral type of theChloris family.[10]: 23
In June 2008, a rotationallightcurve ofAinonai was obtained fromphotometric observations by James W. Brinsfield at the Via Capote Observatory (G69) in California. Lightcurve analysis gave arotation period of (38.31±0.05) hours with a brightness variation of (0.30±0.02)magnitude (U=3–).[8]
According to observations from theNEOWISE mission of NASA's space-basedWide-field Infrared Survey Explorer,Ainonai measures (10.920±0.122) kilometers in diameter and its surface has analbedo of (0.112±0.011).[7] TheCollaborative Asteroid Lightcurve Link assumes a standard albedo for acarbonaceous asteroid of 0.057 and calculates a diameter of 14.64 kilometers based on anabsolute magnitude of 12.9.[9]
