(343158) 2009 HC82

(343158) 2009 HC82 is an asteroid on a retrograde orbit, classified as near-Earth object of the Apollo group. The estimated 2-kilometer sized asteroid makes many close approaches to Earth, Venus, and Mars at a very high relative velocity. It may be an extinct comet or damocloid asteroid.

(343158) 2009 HC82
Discovery[1]
Discovered byCatalina Sky Survey
Discovery siteMount Lemmon Obs.
Discovery date29 April 2009
Designations
(343158) 2009 HC82
Apollo · NEO [2]
Retrograde
Orbital characteristics[2]
Epoch 13 January 2016 (JD 2457400.5)
Uncertainty parameter 1
Observation arc4394 days (12.03 yr)
Aphelion4.5665 AU (683.14 Gm)
Perihelion0.48904 AU (73.159 Gm)
2.5278 AU (378.15 Gm)
Eccentricity0.80653
4.02 yr (1467.9 d)
284.23°
0° 14m 42.864s / day (n)
Inclination154.40°
295.20°
298.71°
Earth MOID0.146217 AU (21.8738 Gm)
Physical characteristics
Mean diameter
1.7 km (est. at 0.22)[3]
3.5 km (est. at 0.05)[3]
~20[1]
16.2[2]

    Description

    2009 HC82 was initially listed as a potentially hazardous asteroid.[1] It was removed from the Sentry Risk Table on 6 May 2009.[4]

    Velocity

    2009 HC82 has a retrograde orbit and thus orbits the Sun in the opposite direction of other objects. Therefore, close approaches to this object can have very high relative velocities. As of 2012, it had the highest relative velocity to Earth of objects that come within 0.5 AU of Earth.[5]

    Close approaches

    On 11 November 2024, 2009 HC82 will pass about 0.485 AU (72,600,000 km; 45,100,000 mi) from Earth, but with a record high relative velocity of about 283,000 km/h (78.66 km/s).[6] Both Halley's Comet (254,000 km/h)[7] and 55P/Tempel-Tuttle (252,800 km/h)[8] have slightly lower relative velocities to Earth. Note however that when the asteroid is one astronomical unit from the sun (as it would be if it ever hit the earth), its relative speed will be less. On 2 February 2053, 2009 HC82 will pass about 0.08 AU from Venus.[6] On 22 October 2060, it may pass about 0.004 AU (600,000 km; 370,000 mi) from Mars.[6]

    Possible damocloid

    The multiple planet crossing and retrograde orbit suggests that this object may be an extinct comet or damocloid asteroid similar to 5335 Damocles, 2008 KV42, and 20461 Dioretsa.[9]

    Diameter

    Based on a generic magnitude-to-diameter conversion, 2009 HC82 measures approximately 1.7 to 3.5 kilometers in diameter, for an absolute magnitude of 16.2 and an assumed albedo between 0.22 and 0.05. Since the true albedo is unknown and it has an absolute magnitude (H) of 16.1,[2] it is about 1.6 to 3.6 km in diameter.[3]

    References
    1. "MPEC 2009-J04 : 2009 HC82". IAU Minor Planet Center. 1 May 2009. Retrieved 8 February 2011.
    2. "JPL Small-Body Database Browser: (2009 HC82)" (last observation: 2010-04-04). Retrieved 8 April 2016.
    3. "Asteroid Size Estimator". CNEOS NASA/JPL. Retrieved 26 January 2018.
    4. "Date/Time Removed". NASA/JPL Near-Earth Object Program Office. Retrieved 19 March 2012.
    5. "NEO Close-Approaches (Between 1900 and 2200)". NASA/JPL Near-Earth Object Program. Retrieved 22 June 2012. (sorted by descending relative velocity, dist<0.5AU = "215,221 close-Earth approaches")
    6. "JPL Close-Approach Data: (2009 HC82)" (last observation: 2010-04-04). Retrieved 9 February 2011.
    7. "JPL Close-Approach Data: 1P/Halley" (last observation: 1994-01-11). Retrieved 9 February 2011.
    8. "JPL Close-Approach Data: 55P/Tempel-Tuttle" (last observation: 1998-07-05). Retrieved 9 February 2011.
    9. Akimasa Nakamura and bas (2 May 2009). "List of Damocloids (Oort cloud asteroids)". Lowell Observatory. Retrieved 9 February 2011.
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