(410777) 2009 FD

(410777) 2009 FD is a carbonaceous sub-kilometer asteroid and binary system,[6][3] classified as near-Earth object and potentially hazardous asteroid of the Apollo group, discovered on 24 February 2009 by astronomers of the Spacewatch program at Kitt Peak National Observatory near Tucson, Arizona, in the United States.[2]

(410777) 2009 FD
Arecibo Observatory radar images of 2009 FD
Discovery[1]
Discovered bySpacewatch
Discovery siteKitt Peak National Obs.
Discovery date24 February 2009
Designations
(410777) 2009 FD
2009 FD
Orbital characteristics[1]
Epoch 3 July 2013 (JD 2456476.5)
Uncertainty parameter 0
Observation arc6.77 yr (2,471 days)
Aphelion1.7361 AU
Perihelion0.5896 AU
1.1629 AU
Eccentricity0.4929
1.25 yr (458 days)
98.579°
0° 47m 9.6s / day
Inclination3.1366°
9.5523°
281.24°
Known satellites1[3]
Earth MOID0.0025 AU (1 LD)
Physical characteristics
Mean diameter
Mass8.3×1010 kg (assumed)[7]
22.1[1][4]

    Until 2019, the asteroid's modelled orbit placed it at risk of a possible future collision with Earth in 2185. With a Palermo Technical Impact Hazard Scale rating of -0.44, it had the fifth highest impact threat[lower-alpha 2] of all known asteroids based on its estimated diameter, kinetic yield, impact probability, and time interval.[12] Observations to 2019 extended the observation arc by four years and detected a favourable Yarkovsky effect, which ruled out impact in 2185.[13] Using observations from 16 November 2020, the asteroid was removed from the Sentry risk table on 19 November 2020.

    Discovery
    2009 FD imaged by the Very Large Telescope in November 2013

    2009 FD was initially announced as discovered on 16 March 2009 by La Sagra Sky Survey.[14] Because there were previous observations found in images taken by the Spacewatch survey some 3 weeks prior, on 24 February 2009, the Minor Planet Center assigned the discovery credit to Spacewatch under the discovery assignment rules.[15][2] 2009 FD made a close pass to Earth on 27 March 2009 at a distance of 0.004172 AU (624,100 km; 387,800 mi)[16][17] and another on 24 October 2010 at 0.0702 AU.[16] 2009 FD was recovered at apparent magnitude 23[lower-alpha 3] on 30 November 2013 by Cerro Paranal Observatory,[2] several months before the close approach of April 2014 when it passed 0.1 AU from Earth.[16] It brightened to roughly apparent magnitude 19.3 around mid-March 2014.[18] One radar Doppler observation of 2009 FD was made in 2014.[1] The October–November 2015 Earth approach was studied by the Goldstone Deep Space Network.[19]

    Binary

    NASA's Near Earth Program originally estimated its size to be 130 metres in diameter based on an assumed albedo of 0.15.[20] This gave it an estimated mass of around 2,800,000 tonnes.[20] But work by Amy Mainzer using NEOWISE data in 2014 showed that it could be as large as 472 metres with an albedo as low as 0.01.[1][5] Because 2009 FD (K09F00D) was only detected in two (W1+W2) of the four wavelengths the suspected NEOWISE diameter is more of an upper limit.[5] Radar observations in 2015 showed it to be a binary asteroid.[6] The primary is 120–180 meters in diameter and the secondary is 60–120 meters in diameter.[6]

    Future approaches

    The JPL Small-Body Database shows that 2009 FD will make two very close approaches in the late 22nd century, in 2185 and 2190. As of 2016, the approach of 29 March 2185 had a 1 in 710 chance of impacting Earth.[7] The nominal 2185 Earth approach distance was 0.009 AU (1,300,000 km; 840,000 mi).[16] Orbit determination for 2190 is complicated by the 2185 close approach.[16] The precise distance that it will pass from Earth and the Moon on 29 March 2185 will determine the 30 March 2190 distance. 2009 FD should pass closer to the Moon than Earth on 29 March 2185.[16] An impact by 2009 FD would cause severe devastation to a large region or tsunamis of significant size.[21]

    Past Earth-impact estimates

    In January 2011, near-Earth asteroid 2009 FD (with observations through 7 December 2010) was listed on the JPL Sentry Risk Table with a 1 in 435 chance of impacting Earth on 29 March 2185.[20] In 2014 (with observations through 5 February 2014, creating an observation arc of 1807 days) the potential 2185 impact was ruled out.[22] Using the 2014 observations, the Yarkovsky effect has become more significant than the position uncertainties.[23][11][24] The Yarkovsky effect has resulted in the 2185 virtual impactor returning. While 2009 FD was estimated to be 470 meters in diameter, it was rated −0.40 on the Palermo Scale, placing it higher on the Sentry Risk Table than any other known object at the time.[12]

    On 14 June 2019, Alessio Del Vigna and colleagues published a new analysis, which incorporates astrometry taken in 2019. Using both JPL's Sentry as well as NEODyS's CLOMON-2 system, the new data allowed a 4-sigma detection of the Yarkovsky effect at (+3.6±0.9)×10−3 AU/Myr. The 2019 observations extended the observation arc from six years to ten years. This ruled out the 2185 impact possibility, leaving the potential impact in 2190 as the only theoretically possible impact until 2250, at a very low probability of 1 in 100 million.[13] On 19 November 2020, the asteroid was finally completely removed from the sentry risk table as all possible impacts, including 2190 and 2250, were ruled out.

    See also

    Notes
    1. Naidu, S. (2015) from observations taken in November 2015: Per private communication with the LCDB. Rotation period of at least 2.5 hours. Diameter estimate of 0.150 kilometers. Summary figures for (410777) at the LCDB
    2. Behind: 99942 Apophis @ 1.10, (89959) 2002 NT7 @ 0.18, (29075) 1950 DA @ 0.17, (144898) 2004 VD17 @ -0.25
    3. At an apparent magnitude of 23, 2009 FD was roughly 4 million times fainter than can be seen with the naked eye.
      Math:

    References
    1. "JPL Small-Body Database Browser: 410777 (2009 FD)" (2015-12-01 last obs.). Jet Propulsion Laboratory. Archived from the original on 16 December 2019. Retrieved 30 January 2018.
    2. "410777 (2009 FD)". Minor Planet Center. Retrieved 30 January 2018.
    3. Johnston, Wm. Robert (27 November 2015). "Asteroids with Satellites Database – (410777) 2009 FD". Johnston's Archive. Retrieved 30 January 2018.
    4. "LCDB Data for (410777)". Asteroid Lightcurve Database (LCDB). Retrieved 30 January 2018.
    5. Mainzer, A.; Bauer, J.; Grav, T.; Masiero, J.; Cutri, R. M.; Wright, E.; et al. (April 2014). "The Population of Tiny Near-Earth Objects Observed by NEOWISE". The Astrophysical Journal. 784 (2): 27. arXiv:1310.2980. Bibcode:2014ApJ...784..110M. doi:10.1088/0004-637X/784/2/110. S2CID 45559179. (listed as K09F00D)
    6. "(410777) 2009 FD". Central Bureau for Astronomical Telegrams. 19 November 2015. Archived from the original on 4 March 2016. Retrieved 9 July 2017.
    7. "Earth Impact Risk Summary: 2009 FD". NASA/JPL Near-Earth Object Program Office. Archived from the original on 18 January 2016. Retrieved 1 May 2014.
    8. Behrend, Raoul. "Asteroids and comets rotation curves – (410777) 2009 FD". Geneva Observatory. Retrieved 30 January 2018.
    9. Carbognani, Albino (January 2011). "Lightcurves and Periods of Eighteen NEAs and MBAs". The Minor Planet Bulletin. 38 (1): 57–63. Bibcode:2011MPBu...38...57C. ISSN 1052-8091.
    10. Koehn, Bruce W.; Bowell, Edward G.; Skiff, Brian A.; Sanborn, Jason J.; McLelland, Kyle P.; Pravec, Petr; et al. (October 2014). "Lowell Observatory Near-Earth Asteroid Photometric Survey (NEAPS) - 2009 January through 2009 June". The Minor Planet Bulletin. 41 (4): 286–300. Bibcode:2014MPBu...41..286K. ISSN 1052-8091.
    11. Spoto, F.; Milani, A.; Farnocchia, D.; Chesley, S. R.; Micheli; Valsecchi; Perna; Hainaut (2014). "Non-gravitational Perturbations and Virtual Impactors: the case of asteroid 2009 FD". Astronomy & Astrophysics. 572: A100. arXiv:1408.0736. Bibcode:2014A&A...572A.100S. doi:10.1051/0004-6361/201424743. S2CID 55524612.
    12. "Sentry Risk Table". NASA Near-Earth Object Program. Archived from the original on 21 January 2016. Retrieved 8 June 2012.
    13. Del Vigna, A.; Roa, J.; Farnocchia, D.; Micheli, M.; Guerra, F.; Spoto, F.; Valsecchi, G. B. (14 June 2019), "Yarkovsky effect detection and updated impact hazard assessment for near-Earth asteroid (410777) 2009 FD", Astronomy & Astrophysics, 627: L11, arXiv:1906.05696, Bibcode:2019A&A...627L..11D, doi:10.1051/0004-6361/201936075, S2CID 189762523
    14. "MPEC 2009-F09 : 2009 FD". IAU Minor Planet Center. 17 March 2009. Retrieved 9 January 2013. (K09F00D)
    15. "MPEC 2010-U20 : Editorial Notice". IAU Minor Planet Center. 19 October 2010. Retrieved 29 December 2014.
    16. "JPL Close-Approach Data: (2009 FD)" (last observation: 2014-04-07; arc: 5.11 years). Archived from the original on 19 December 2013. Retrieved 1 May 2014.
    17. Near Earth Asteroid 2009 FD - whilst you were sleeping! (ice in space)
    18. "2009 FD Ephemerides for 1 April 2014". NEODyS (Near Earth Objects – Dynamic Site). Retrieved 17 December 2013.
    19. Dr. Lance A. M. Benner (17 March 2014). "Goldstone Asteroid Schedule". NASA/JPL Asteroid Radar Research. Archived from the original on 19 November 1996. Retrieved 21 March 2014.
    20. "Earth Impact Risk Summary: 2009 FD (arc=650 days)" (2011-01-11 computed on 14 December 2010). Wayback Machine: JPL. Archived from the original on 11 January 2011. Retrieved 14 February 2014. (2.3e-03 = 1 in 435 chance)
    21. Chapman, Clark R. (9 January 2003). "How a Near-Earth Object Impact Might Affect Society" (PDF). OECD. Archived from the original (PDF) on 17 February 2005. Retrieved 14 November 2018.
    22. "Earth Impact Risk Summary: 2009 FD (arc=1807 days)" (2014-02-10 computed on 7 February 2014). Wayback Machine: JPL. Archived from the original on 10 February 2014. Retrieved 1 May 2014.
    23. "(410777) 2009FD". NEODyS (Near Earth Objects – Dynamic Site). Retrieved 1 May 2014. (2.64e-3 = 1 in 379 chance)
    24. "Sentry Notes". NASA/JPL Near-Earth Object Program Office. Archived from the original on 16 February 2011. Retrieved 1 May 2014.
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