| Discovery[1] | |
|---|---|
| Discovered by | Spacewatch |
| Discovery site | Kitt Peak National Obs. |
| Discovery date | 10 January 1997 |
| Designations | |
| (162058) 1997 AE12 | |
| 1997 AE12 | |
| Orbital characteristics[1] | |
| Epoch 4 September 2017 (JD 2458000.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 22.50 yr (8,218 days) |
| Aphelion | 3.6785 AU |
| Perihelion | 1.0554 AU |
| 2.3670 AU | |
| Eccentricity | 0.5541 |
| 3.64 yr (1,330 days) | |
| 296.49° | |
| 0° 16m 14.52s / day | |
| Inclination | 4.8519° |
| 304.82° | |
| 60.820° | |
| Earth MOID | 0.0881 AU (34.3 LD) |
| Physical characteristics | |
| Dimensions | |
| 1880±595h[a] | |
(162058) 1997 AE12 is a stony, sub-kilometerasteroid and likely theslowest rotator known to exist. It is classified asnear-Earth object of theAmor group and measures approximately 800 meters in diameter. The asteroid was discovered on 10 January 1997 by theSpacewatch survey atKitt Peak National Observatory nearTucson, Arizona[2].
1997 AE12 is anAmor asteroid, a group ofnear-Earth object that approach the orbit of Earth from beyond, but do not cross it. It orbits the Sun at a distance of 1.1–3.7 AU once every 3 years and 8 months (1,330 days). Its orbit has aneccentricity of 0.55 and aninclination of 5° with respect to theecliptic.[1]
Published by theDigitized Sky Survey, a firstprecovery was taken at the AustralianSiding Spring Observatory in July 1992, extending the body'sobservation arc by more than 4 years prior to its official discovery observation at Kitt Peak.[2]
1997 AE12 occasionally makes close approaches toEarth andMars. It has an Earthminimum orbital intersection distance of 0.0881 AU (13,200,000 km), which is about 34.3lunar distances.[1]
Its closest recorded approach to Earth took place on 30 August 2003, when the asteroid came within 0.1238 AU (18,500,000 km) from Earth. It will come closer still on 8 October 2145, when it will be within 0.1042 AU (15,590,000 km) from Earth. The asteroid will make its closest approach to Mars on 29 December 2054 when it will come within 0.0376 AU (5,620,000 km) from the planet.[1]
1997 AE12 is a rareQ-type asteroid with a very dark surface, reflecting only about 7% of the light it receives.[5][failed verification] It has also been described a common stonyS-type asteroid.[3]
The most unusual feature of1997 AE12, however, is its exceptionally slowrotation period of1880±595 hours, or approximately 11 weeks (U=2).[a] It holds the record for being theslowest-rotating asteroid discovered so far. Its precise period with a smaller error margin still needs to be determined. Thelightcurve also showed a high brightness variation of at least 0.6magnitude, which is indicative for a non-spherical shape.[3][a] The asteroid may also be in a tumbling motion, but observations are not sufficient to determine any non-principal axis rotation.[6]
Like other slowly-rotating asteroids such as912 Maritima, it is possible that the extremely long period of this asteroid is caused byYORP radiation pressure slowing down the asteroid's rotation.[7] This is especially likely considering that1997 AE12 has a very low albedo, which would allow it to absorb moreradiant energy from the Sun. Furthermore, the YORP effect has also been observed on other Q-type asteroids such as1862 Apollo.[8]
According to the survey carried out by theNEOWISE mission of NASA'sWide-field Infrared Survey Explorer,1997 AE12 measures 0.847 kilometers in diameter and its surface has analbedo of 0.186.[4] TheCollaborative Asteroid Lightcurve Link assumes a standard albedo forstony asteroids of 0.20 and calculates a diameter of 0.782 kilometers based on anabsolute magnitude of 17.9.[3]
As of 2017, this asteroid remainsunnamed.[2]
