(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 by	Catalina Sky Survey
Discovery site	Mount Lemmon Obs.
Discovery date	29 April 2009
Designations
MPC designation	(343158) 2009 HC82
Minor planet category	Apollo · NEO [2] Retrograde
Orbital characteristics[2]
Epoch 13 January 2016 (JD 2457400.5)
Uncertainty parameter 1
Observation arc	4394 days (12.03 yr)
Aphelion	4.5665 AU (683.14 Gm)
Perihelion	0.48904 AU (73.159 Gm)
Semi-major axis	2.5278 AU (378.15 Gm)
Eccentricity	0.80653
Orbital period	4.02 yr (1467.9 d)
Mean anomaly	284.23°
Mean motion	0° 14^m 42.864^s / day (n)
Inclination	154.40°
Longitude of ascending node	295.20°
Argument of perihelion	298.71°
Earth MOID	0.146217 AU (21.8738 Gm)
Physical characteristics
Mean diameter	1.7 km (est. at 0.22)[3] 3.5 km (est. at 0.05)[3]
Apparent magnitude	~20[1]
Absolute magnitude (H)	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. 2009-05-01. Retrieved 2011-02-08.
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 2012-03-19.
5. "NEO Close-Approaches (Between 1900 and 2200)". NASA/JPL Near-Earth Object Program. Retrieved 2012-06-22. (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 2011-02-09.
7. "JPL Close-Approach Data: 1P/Halley" (last observation: 1994-01-11). Retrieved 2011-02-09.
8. "JPL Close-Approach Data: 55P/Tempel-Tuttle" (last observation: 1998-07-05). Retrieved 2011-02-09.
9. Akimasa Nakamura and bas (2009-05-02). "List of Damocloids (Oort cloud asteroids)". Lowell Observatory. Retrieved 2011-02-09.

External links

• 2009 news images (HohmannTransfer.com)
• (343158) 2009 HC82 at the JPL Small-Body Database
  • Close approach · Discovery · Ephemeris · Orbit diagram · Orbital elements · Physical parameters