| 词条 | (343158) 2009 HC82 |
| 释义 |
| minorplanet = yes | background = #FFC2E0 | name = {{mp|(343158) 2009 HC|82}} | image = | caption = | discovery_ref = [1] | discoverer = Catalina Sky Survey | discovery_site = Mount Lemmon Obs. | discovered = 29 April 2009 | mpc_name = {{mp|(343158) 2009 HC|82}} | mp_category = Apollo{{·}}NEO [2] Retrograde | orbit_ref = [2] | epoch = 13 January 2016 (JD 2457400.5) | aphelion = {{Convert|4.5665|AU|Gm|abbr=on|lk=on}} | perihelion = {{Convert|0.48904|AU|Gm|abbr=on}} | semimajor = {{Convert|2.5278|AU|Gm|abbr=on}} | eccentricity = 0.80653 | period = 4.02 yr (1467.9 d) | inclination = 154.40° | asc_node = 295.20° | mean_anomaly = 284.23° | arg_peri = 298.71° | mean_diameter = 1.7 km {{small|(est. at 0.22)}} 3.5 km {{small|(est. at 0.05)}} | rotation = | albedo = | spectral_type = | magnitude = ~20[1] | abs_magnitude = 16.2[2] | mean_motion = {{Deg2DMS|0.24524|sup=ms}} / day (n) | observation_arc = 4394 days (12.03 yr) | uncertainty = 1 | moid = {{Convert|0.146217|AU|Gm|abbr=on}} }} {{mp|(343158) 2009 HC|82}} 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. Description{{mp|2009 HC|82}} was initially listed as a potentially hazardous asteroid.[1] It was removed from the Sentry Risk Table on 6 May 2009.[9]Velocity{{mp|2009 HC|82}} 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.[10]Close approachesOn 11 November 2024, {{mp|2009 HC|82}} will pass about {{convert|0.485|AU|km mi|abbr=on|lk=on}} from Earth, but with a record high relative velocity of about 283,000 km/h (78.66 km/s).[3] Both Halley's Comet (254,000 km/h)[4] and 55P/Tempel-Tuttle (252,800 km/h)[5] 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, {{mp|2009 HC|82}} will pass about 0.08 AU from Venus.[3] On 22 October 2060, it may pass about {{convert|0.004|AU|km mi|abbr=on|lk=on}} from Mars.[3] Possible damocloidThe multiple planet crossing and retrograde orbit suggests that this object may be an extinct comet or damocloid asteroid similar to 5335 Damocles, {{mpl|2008 KV|42}}, and 20461 Dioretsa.[16] DiameterBased on a generic magnitude-to-diameter conversion, {{mp|2009 HC|82}} 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. References1. ^1 2 {{Cite web |title=MPEC 2009-J04 : 2009 HC82 |publisher=IAU Minor Planet Center |date=2009-05-01 |url=http://www.minorplanetcenter.org/mpec/K09/K09J04.html |accessdate=2011-02-08}} [6][7][8]2. ^1 2 3 {{Cite web |type=last observation: 2010-04-04 |title=JPL Small-Body Database Browser: (2009 HC82) |url=http://ssd.jpl.nasa.gov/sbdb.cgi?sstr=2009HC82 |accessdate=8 April 2016}} 3. ^1 2 {{cite web |type=last observation: 2010-04-04 |title=JPL Close-Approach Data: (2009 HC82) |url=http://ssd.jpl.nasa.gov/sbdb.cgi?sstr=2009HC82;cad=1#cad |accessdate=2011-02-09}} 4. ^{{cite web |type=last observation: 1994-01-11 |title=JPL Close-Approach Data: 1P/Halley |url=http://ssd.jpl.nasa.gov/sbdb.cgi?sstr=1P;cad=1#cad |accessdate=2011-02-09}} 5. ^{{cite web |type=last observation: 1998-07-05 |title=JPL Close-Approach Data: 55P/Tempel-Tuttle |url=http://ssd.jpl.nasa.gov/sbdb.cgi?sstr=55P;cad=1#cad |accessdate=2011-02-09}} 6. ^1 {{cite web |title=Date/Time Removed |publisher=NASA/JPL Near-Earth Object Program Office |url=http://neo.jpl.nasa.gov/risk/removed.html |accessdate=2012-03-19}} 7. ^1 {{Cite web |title=NEO Close-Approaches (Between 1900 and 2200) |publisher=NASA/JPL Near-Earth Object Program |url=http://neo.jpl.nasa.gov/cgi-bin/neo_ca?type=NEO&hmax=all&sort=v_rel&sdir=DESC&tlim=all&dmax=0.5AU&max_rows=50&action=Display+Table&show=1 |accessdate=2012-06-22}} (sorted by descending relative velocity, dist<0.5AU = "215,221 close-Earth approaches") 8. ^1 {{cite web |date=2009-05-02 |title=List of Damocloids (Oort cloud asteroids) |publisher=Lowell Observatory |author=Akimasa Nakamura and bas |url=ftp://ftp.lowell.edu/pub/bas/damocloid |accessdate=2011-02-09}} }} External links
5 : Apollo asteroids|Discoveries by CSS|Damocloids|Asteroids removed from the Sentry Risk Table|Astronomical objects discovered in 2009 |
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