 Radar images of2014 SR339 taken by theArecibo Observatory on 9 February 2018 | |
| Discovery[1] | |
|---|---|
| Discovered by | WISE |
| Discovery site | Earth orbit |
| Discovery date | 30 September 2014 |
| Designations | |
| (505657)2014 SR339 | |
| 2014 SR339 | |
| Apollo · NEO · PHA[1][2] | |
| Orbital characteristics[2] | |
| Epoch 23 March 2018 (JD 2458200.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 3.41yr (1,245 d) |
| Aphelion | 1.6948AU |
| Perihelion | 0.9046 AU |
| 1.2997 AU | |
| Eccentricity | 0.3040 |
| 1.48 yr (541 d) | |
| 60.524° | |
| 0° 39m 54.72s / day | |
| Inclination | 29.790° |
| 138.78° | |
| 299.60° | |
| Earth MOID | 0.0354 AU (13.8 LD) |
| Physical characteristics | |
| Dimensions | (>1.5 km × ? km)[3] |
| 0.971±0.367 km[4] | |
| 8–9 h[5] 8.729 h[3][a] | |
| 0.068±0.074[4] | |
| C(assumed on albeo) | |
| 18.6[2] | |
(505657) 2014 SR339, provisional designation2014 SR339, is a dark and elongatedasteroid, classified asnear-Earth object andpotentially hazardous asteroid of theApollo group, approximately 970 meters (3,200 feet) in diameter. It was discovered on 30 September 2014, by NASA'sWide-field Infrared Survey Explorer telescope (WISE) in Earth's orbit.[1] Closely observed atGoldstone andArecibo in February 2018, it has a rotation period of 8.7 hours.[5]
2014 SR339 is a member of theApollo asteroids, whichcross the orbit of Earth. Apollo's are the largest group ofnear-Earth objects with nearly 10 thousand known objects. It orbits the Sun at a distance of 0.90–1.70 AU once every 18 months (541 days;semi-major axis of 1.30 AU). Its orbit has aneccentricity of 0.30 and aninclination of 30° with respect to theecliptic.[2] With anaphelion of 1.70 AU, it is also aMars-crosser, as it crosses the orbit of the Red Planet at 1.666 AU. The body'sobservation arc begins with its official discovery observation by WISE in September 2014.[1]
As apotentially hazardous asteroid,2014 SR339 has aminimum orbital intersection distance (MOID) with Earth of less than 0.05 AU and a diameter of greater than 150 meters. The Earth-MOID is currently 0.0354 AU (5,300,000 km), which translates into 13.8lunar distances (LD).[2]
On 7 February 2018 it passed 0.054 AU (21 LD) from the Earth when itsapparent magnitude brightened to 14.[3]Goldstone observed it until the following day.[6] While this was an 8.1-million kilometer flyby, the next close flyby of 6.3 million km will occur on 5 February 2058, and another 7.6 million km on 8 February 2095. It will also have a 3.2 million km flyby of Mars on 26 September 2048.[7]
The asteroid'sspectral type is unknown. Due to its unusually low albedo(see below) it is likely a carbonaceousC-type asteroid.[2]
On 9 February, radiometric observations by theArecibo Observatory revealed that the asteroid has an elongated, lumpy shape.[3] The radar images also gave it arotational period between 8 and 9 hours.[5] A refined period of 8.7 hour agrees with (photometric)lightcurve observations by American photometristBrian Warner at the Center for Solar System Studies (U82) during 9–11 February 2018, who obtained a period of 8.729 hours with a high brightness amplitude of 0.93magnitude, which also indicates a non-spheroidal shape (U=3-).[3][a]
According to the survey carried out by theNEOWISE mission of NASA's WISE telescope,2014 SR339 measures 0.971 kilometers in diameter and its surface has analbedo of 0.068.[4] During its close approach in February 2018, radiometric observations by Arecibo Observatory determined that the object is at least 1.5 kilometers (0.93 miles) wide.[3] Data from theArecibo Telescope released in 2022 showed an unusually high radar albedo, possibly indicating rich metal content.[8]
Thisminor planet was numbered by theMinor Planet Center on 4 November 2017 (M.P.C. 107069).[9] As of 2018, it has not beennamed.[1]
Recent radar images of near-Earth asteroid (505657) 2014 SR339 from @NAICobservatory show a lumpy, elongated body at least 1.5 km long and rotating once every 8 to 9 hours!
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