_Aci.png) Shape model ofAci from itslightcurve | |
| Discovery[1] | |
|---|---|
| Discovered by | E. F. Helin |
| Discovery site | Palomar Obs. |
| Discovery date | 9 July 1991 |
| Designations | |
| (6522) Aci | |
| Pronunciation | Italian:[ˈaːtʃi] |
Named after | ItalianJaci river atAcireale (Acis and Galatea)[2] |
| 1991 NQ · 1990 BH4 | |
| main-belt[1][3] · Phocaea[4][5] | |
| Orbital characteristics[3] | |
| Epoch 4 September 2017 (JD 2458000.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 27.36 yr (9,995 days) |
| Aphelion | 2.8595AU |
| Perihelion | 1.9107 AU |
| 2.3851 AU | |
| Eccentricity | 0.1989 |
| 3.68yr (1,345 days) | |
| 68.743° | |
| 0° 16m 3.36s / day | |
| Inclination | 22.109° |
| 294.45° | |
| 314.18° | |
| Physical characteristics | |
| 5.65 km(calculated)[4] 6.125±0.119 km km[6][7] | |
| 7.6921±0.0017 h[8] | |
| 0.23(assumed)[4] 0.392±0.029[6][7] | |
| S(family-based)[5][4] | |
| 12.7[6] · 13.0[3] · 13.003±0.005(R)[8] · 13.1[1] · 13.45[4] | |
6522 Aci (prov. designation:1991 NQ) is an elongatedPhocaea asteroid from the inner regions of theasteroid belt. It was discovered on 9 July 1991, by American astronomerEleanor Helin atPalomar Observatory in California, United States.[1] The likely stonyS-type asteroid has arotation period of 5.65 hours and measures approximately 6 kilometers (3.7 miles) in diameter. It was named for theJaci river atAcireale in Italy, and refers to the myth ofAcis and Galatea.
Aci is a member of thePhocaea family (701),[5] a relatively small group ofstony asteroids with similar orbital characteristics. It orbits the Sun in theinner main-belt at a distance of 1.9–2.9 AU once every 3 years and 8 months (1,345 days). Its orbit has aneccentricity of 0.20 and aninclination of 22° with respect to theecliptic.[3] In January 1990, the asteroid was first observed as1990 BH4 at the GermanKarl Schwarzschild Observatory, extending the body'sobservation arc by 17 months prior to its official discovery observation at Palomar.[1]
Thisminor planet was named for theJaci river nearAcireale, southeast of Mount Etna inSicily, Italy. Other towns and villages along the river, such asAci Castello,Aci Trezza, andAci Sant'Antonio, were also honored.[2] The river's name refers to the mythAcis and Galatea fromGreek mythology, which is about a young Sicilian shepherd, who was killed by the jealous cyclopsPolyphemus, because of his love for the sea nymph Galatea. The minor planet74 Galatea is named after thisNereid.[2] Theapproved naming citation was published by theMinor Planet Center on 26 October 1996(M.P.C. 28090).[9]
In September 2010, a rotationallightcurve ofAci was obtained fromphotometric observations taken at thePalomar Transient Factory in California. Lightcurve analysis gave arotation period of7.6921 hours with a brightness variation of 0.68magnitude (U=2).[8]
According to theNEOWISE mission of NASA'sWide-field Infrared Survey Explorer,Aci measures 6.1 kilometers in diameter and its surface has a highalbedo of 0.39,[6][7] while theCollaborative Asteroid Lightcurve Link assumes an albedo of 0.23 – which derives from25 Phocaea, namesake and largest member of this orbital family – and calculates a diameter of 5.7 kilometers with anabsolute magnitude of 13.45.[4]
