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(505657) 2014 SR339

(505657) 2014 SR339, provisional designation 2014 SR339, is a dark and elongated asteroid, classified as near-Earth object and potentially hazardous asteroid of the Apollo group, approximately 970 meters (3,200 feet) in diameter. It was discovered on 30 September 2014, by NASA's Wide-field Infrared Survey Explorer telescope (WISE) in Earth's orbit.[1] Closely observed at Goldstone and Arecibo in February 2018, it has a rotation period of 8.7 hours.[5]

(505657) 2014 SR339
Radar images of 2014 SR339 taken by the Arecibo Observatory on 9 February 2018
Discovery[1]
Discovered byWISE
Discovery siteEarth orbit
Discovery date30 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 arc3.41 yr (1,245 d)
Aphelion1.6948 AU
Perihelion0.9046 AU
1.2997 AU
Eccentricity0.3040
1.48 yr (541 d)
60.524°
0° 39m 54.72s / day
Inclination29.790°
138.78°
299.60°
Earth MOID0.0354 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]

Orbit and classification

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2014 SR339 is a member of the Apollo asteroids, which cross the orbit of Earth. Apollo's are the largest group of near-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 an eccentricity of 0.30 and an inclination of 30° with respect to the ecliptic.[2] With an aphelion of 1.70 AU, it is also a Mars-crosser, as it crosses the orbit of the Red Planet at 1.666 AU. The body's observation arc begins with its official discovery observation by WISE in September 2014.[1]

Close approaches

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As a potentially hazardous asteroid, 2014 SR339 has a minimum 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 13.8 lunar distances (LD).[2]

2018 flyby

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On 7 February 2018 it passed 0.054 AU (21 LD) from the Earth when its apparent 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]

Physical characteristics

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The asteroid's spectral type is unknown. Due to its unusually low albedo (see below) it is likely a carbonaceous C-type asteroid.[2]

Rotation period

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On 9 February, radiometric observations by the Arecibo Observatory revealed that the asteroid has an elongated, lumpy shape.[3] The radar images also gave it a rotational period between 8 and 9 hours.[5] A refined period of 8.7 hour agrees with (photometric) lightcurve observations by American photometrist Brian 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 0.93 magnitude, which also indicates a non-spheroidal shape (U=3-).[3][a]

Diameter and albedo

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According to the survey carried out by the NEOWISE mission of NASA's WISE telescope, 2014 SR339 measures 0.971 kilometers in diameter and its surface has an albedo 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 the Arecibo Telescope released in 2022 showed an unusually high radar albedo, possibly indicating rich metal content.[8]

Numbering and naming

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This minor planet was numbered by the Minor Planet Center on 4 November 2017 (M.P.C. 107069).[9] As of 2018, it has not been named.[1]

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  •  
    Daily motion of asteroid across sky
  •  
    View of flyby above the earth and moon

Notes

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  1. ^ a b lightcurve plot of (505657) 2014 SR339: rotation period 8.729±0.002 hours with a brightness amplitude of 0.93 mag. Quality code of 3-. Summary figures at the Center for Solar System Studies (CS3)

References

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  1. ^ a b c d e "505657 (2014 SR339)". Minor Planet Center. Retrieved 5 March 2018.
  2. ^ a b c d e f "JPL Small-Body Database Browser: 505657 (2014 SR339)" (2018-02-26 last obs.). Jet Propulsion Laboratory. Retrieved 5 March 2018.
  3. ^ a b c d e f "Near-Earth asteroid (505657) 2014 SR339". Arecibo Observatory – NASA/JPL. 14 February 2018. Retrieved 5 March 2018.
  4. ^ a b c Nugent, C. R.; Mainzer, A.; Masiero, J.; Bauer, J.; Cutri, R. M.; Grav, T.; et al. (December 2015). "NEOWISE Reactivation Mission Year One: Preliminary Asteroid Diameters and Albedos". The Astrophysical Journal. 814 (2): 13. arXiv:1509.02522. Bibcode:2015ApJ...814..117N. doi:10.1088/0004-637X/814/2/117. S2CID 9341381.
  5. ^ a b c "Recent radar images of (505657) 2014 SR339". Twitter. Retrieved 5 March 2018. 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!
  6. ^ "Goldstone Radar Observations Planning: Asteroids 2002 AJ129, 2014 SR339, 2015 BN509, and 2018 CB". Lance Benner – NASA/JPL. Retrieved 5 March 2018.
  7. ^ "Asteroid 505657 2014 SR339". asteroidsnear.com. Retrieved 5 March 2018.
  8. ^ Colin Stuart (1 November 2022), "ARECIBO LEGACY: NEW DATA ON NEAR-EARTH ASTEROIDS", Sky & Telescope
  9. ^ "MPC/MPO/MPS Archive". Minor Planet Center. Retrieved 5 March 2018.
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