View source for Astronomy:(391211) 2006 HZ51

{{DISPLAYTITLE:{{mp|(391211) 2006 HZ|51}}}}
{{Infobox planet
 | minorplanet     = yes
 | name            = {{mp|(391211) 2006 HZ|51}}
 | background      = #FFC2E0
 | image           = 
 | image_size      = 
 | caption         = 
 | discovery_ref   = <ref name="jpldata" />
 | discoverer      = [[Astronomy:Catalina Sky Survey|Catalina Sky Srvy.]]
 | discovery_site  = [[Astronomy:Mount Lemmon Observatory|Mount Lemmon Obs.]]
 | discovered      = 27 April 2006
 | mpc_name        = (391211) {{mp|2006 HZ|51}}
 | alt_names       = {{mp|2006 HZ|51}}
 | pronounced      = 
 | named_after     = <!--xafter<br />{{small|(description)}}<ref MPC-object" />-->
 | mp_category     = {{nowrap|[[Astronomy:Amor asteroid|Amor]]{{·}}[[Astronomy:Near-Earth object|NEO]]{{·}}[[Astronomy:Potentially hazardous object|PHA]]<ref name="jpldata" /><ref name="MPC-object" />}}
 | orbit_ref       = <ref name="jpldata" />
 | epoch           = 4 September 2017 ([[Astronomy:Julian day|JD]] 2458000.5)
 | uncertainty     = 0
 | observation_arc = 16.10 yr (5,882 days)
 | aphelion        = 2.7511 [[Astronomy:Astronomical unit|AU]]
 | perihelion      = 1.0438 AU
 | semimajor       = 1.8974 AU
 | eccentricity    = 0.4499
 | period          = 2.61 [[Astronomy:Julian year|yr]] (955 days)
 | mean_anomaly    = 86.571[[Degree (angle)|°]]
 | mean_motion     = {{Deg2DMS|0.3771|sup=ms}} / day
 | inclination     = 12.412°
 | asc_node        = 84.291°
 | arg_peri        = 193.34°
 | moid            = 0.0354 AU (13.8 [[Astronomy:Lunar distance|LD]])
 | mean_diameter   = {{val|0.412|0.089}} km<ref name="Nugent-2015" /><br />0.8 km {{small|(estimate)}}<ref name="NewScientist" />
 | rotation        = 
 | albedo          = {{val|0.415|0.233}}<ref name="Nugent-2015" />
 | spectral_type   = 
 | abs_magnitude   = 18.5<ref name="jpldata" />
}}

'''{{mp|(391211) 2006 HZ|51}}''' is a bright, sub-kilometer [[Astronomy:Asteroid|asteroid]] on an eccentric orbit, classified as a [[Astronomy:Near-Earth object|near-Earth object]] and a [[Astronomy:Potentially hazardous asteroid|potentially hazardous asteroid]] of the [[Astronomy:Amor asteroid|Amor group]]. It was discovered on 27 April 2006, by astronomers of the [[Astronomy:Catalina Sky Survey|Catalina Sky Survey]] conducted at [[Astronomy:Mount Lemmon Observatory|Mount Lemmon Observatory]], Arizona, {{wipe|United States}}.<ref name="MPC-object" /> During preliminary observations, it was thought to have a small chance of [[Astronomy:Impact event|impacting Earth]] in 2008.<ref name="NewScientist"/>  The asteroid measures approximately half a kilometer in diameter and has an exceptionally high [[Astronomy:Astronomical albedo|albedo]].<ref name="Nugent-2015" />

== Orbit and classification ==

{{mp|2006 HZ|51}} is an [[Astronomy:Amor asteroid|Amor asteroid]] – a subgroup of [[Astronomy:Near-Earth asteroid|near-Earth asteroid]]s that approach the orbit of Earth from beyond, but do not cross it.<ref name="jpldata" /><ref name="MPC-object" />

It orbits the Sun at a distance of 1.04–2.75&nbsp;[[Astronomy:Astronomical unit|AU]] once every 2 years and 7 months (955 days; semi-major axis of 1.90&nbsp;AU). Its orbit has an [[Astronomy:Orbital eccentricity|eccentricity]] of 0.45 and an [[Astronomy:Orbital inclination|inclination]] of 12[[Degree (angle)|°]] with respect to the [[Astronomy:Ecliptic|ecliptic]].<ref name="jpldata" /> The body's [[Astronomy:Observation arc|observation arc]] begins with a [[Astronomy:Precovery|precovery]] taken by [[Organization:Near-Earth Asteroid Tracking|NEAT]] at [[Organization:Palomar Observatory|Palomar Observatory]] in October 2001.<ref name="MPC-object" /> With an aphelion of 2.75&nbsp;AU, and typical for members of the Amor group, this asteroid is also a [[Astronomy:Mars-crosser|Mars-crosser]], crossing the orbit of the Red Planet at 1.666&nbsp;AU.

=== Close approaches ===

{{mp|2006 HZ|51}} has a minimum orbital intersection distance (MOID) with Earth of {{convert |0.035385 |AU |km |abbr=on |lk=off |sigfig=3 |order=flip}}, which translates into 13.8 [[Astronomy:Lunar distance|lunar distances]].<ref name="jpldata" />

This makes it a [[Astronomy:Potentially hazardous asteroid|potentially hazardous asteroid]], a body with a threatening close approach to the Earth, due to its low MOID and large size ([[Astronomy:Absolute magnitude|absolute magnitude]] of 18.5). Such asteroids are defined to have an absolute magnitude of 22 or brighter – which generically corresponds to a diameter of approximately 140 meters – and a MOID that is smaller than 0.05&nbsp;AU or 19.5&nbsp;LD.

Based on a short [[Astronomy:Observation arc|observation arc]] of only 1.1 days, it was originally thought to have a 1 in 6 million chance of hitting Earth on 21 June 2008.<ref name="NewScientist"/> Further refinement of the [[Physics:Orbit|orbit]] quickly eliminated the risk. The preliminary 2-day orbit solution on 28 April 2006 was at first thought to have a period of 7 years and a perihelion of approximately 1.1&nbsp;AU (MPEC 2006-H58).

== Physical characteristics ==

=== Diameter and albedo ===

According to the survey carried out by the [[Astronomy:NEOWISE|NEOWISE]] mission of NASA's [[Astronomy:Wide-field Infrared Survey Explorer|Wide-field Infrared Survey Explorer]], {{mp|2006 HZ|51}} measures 412 meters in diameter and its surface has an exceptionally high [[Astronomy:Astronomical albedo|albedo]] of 0.415.<ref name="Nugent-2015" /> Other source give an estimated diameter of 800 meters.<ref name="NewScientist" />

=== Rotation period ===

As of 2018, n rotational [[Astronomy:Lightcurve|lightcurve]] of {{mp|2006 HZ|51}} has been obtained from photometric observations. The body's [[Rotation period|rotation period]], [[Astronomy:Poles of astronomical bodies|pole]] and shape remains unknown.<ref name="jpldata" /><ref name="lcdb" />

== Naming ==

This [[Astronomy:Minor planet|minor planet]] has not yet been named.<ref name="MPC-object" />

== References ==
{{reflist|30em|refs=

<ref name="jpldata">{{cite web
  |type       = 2017-11-21 last obs.
  |title      = JPL Small-Body Database Browser: 391211 (2006 HZ51)
  |url        = https://ssd.jpl.nasa.gov/sbdb.cgi?sstr=2391211
  |publisher  = [[Organization:Jet Propulsion Laboratory|Jet Propulsion Laboratory]]
  |accessdate = 30 January 2018}}</ref>

<ref name="Nugent-2015">{{cite journal
  |display-authors = 6
  |first1     = C. R. |last1 = Nugent
  |first2     = A. |last2 = Mainzer
  |first3     = J. |last3 = Masiero
  |first4     = J. |last4 = Bauer
  |first5     = R. M. |last5 = Cutri
  |first6     = T. |last6 = Grav
  |first7     = E. |last7 = Kramer
  |first8     = S. |last8 = Sonnett
  |first9     = R. |last9 = Stevenson
  |first10    = E. L. |last10 = Wright
  |date       = December 2015
  |title      = NEOWISE Reactivation Mission Year One: Preliminary Asteroid Diameters and Albedos
  |url        = http://adsabs.harvard.edu/cgi-bin/bib_query?bibcode=2015ApJ...814..117N
  |journal    = The Astrophysical Journal
  |volume     = 814
  |issue      = 2
  |page       = 13
  |bibcode    = 2015ApJ...814..117N
  |doi        = 10.1088/0004-637X/814/2/117
  |arxiv      = 1509.02522
  |s2cid = 9341381 |access-date= 30 January 2018}}</ref>

<ref name="MPC-object">{{cite web
  |title      = 391211 (2006 HZ51)
  |work       = [[Organization:Minor Planet Center|Minor Planet Center]]
  |url        = https://www.minorplanetcenter.net/db_search/show_object?object_id=391211
  |accessdate = 30 January 2018}}</ref>

<ref name="NewScientist">{{cite web
  |title      = Big new asteroid has slim chance of hitting Earth
  |work       = New Scientist
  |date       = 2 May 2006
  |url        = https://www.newscientist.com/article/dn9095-big-new-asteroid-has-slim-chance-of-hitting-earth
  |accessdate = 30 January 2018}}</ref>

<ref name="lcdb">{{cite web
  |title      = LCDB Data for (391211) 
  |publisher  = Asteroid Lightcurve Database (LCDB)
  |url        = http://www.minorplanet.info/PHP/generateOneAsteroidInfo.php?AstInfo=391211%7C
  |accessdate = 30 January 2018}}</ref>

}} <!-- end of reflist -->

== External links ==
* [http://www.minorplanet.info/PHP/lcdbsummaryquery.php Asteroid Lightcurve Database (LCDB)], query form ([http://www.minorplanet.info/lightcurvedatabase.html info] {{Webarchive|url=https://web.archive.org/web/20171216050541/http://www.minorplanet.info/lightcurvedatabase.html |date=16 December 2017 }})
* [http://obswww.unige.ch/~behrend/page_cou.html Asteroids and comets rotation curves, CdR] – Observatoire de Genève, Raoul Behrend
* {{NeoDys|391211}}
* {{ESA-SSA|391211|2006HZ51}}
* {{JPL small body}}

{{Minor planets navigator | |number=391211 |PageName={{mp|(391211) 2006 HZ|51}} | }}
{{Small Solar System bodies}}

{{DEFAULTSORT:2006 HZ51}}
[[Category:Amor asteroids|391211]]
[[Category:Potentially hazardous asteroids|391211]]

{{Sourceattribution|(391211) 2006 HZ51}}