| 词条 | 20461 Dioretsa |
| 释义 |
| minorplanet = yes | name = 20461 Dioretsa | background = #C7FF8F | image = | image_size = | caption = | discovery_ref = [1] | discoverer = LINEAR | discovery_site = Lincoln Lab ETS | discovered = 8 June 1999 | mpc_name = (20461) Dioretsa | alt_names = {{mp|1999 LD|31}} | pronounced = {{nowrap|{{IPAc-en|d|aɪ|.|ə|ˈ|r|ɛ|t|s|ə}} {{respell|dy-ə|RET|sə}}}} | named_after = Asteroid [2] {{small|(spelled backwards)}} | mp_category = centaur{{·}}damocloid [4] unusual [5]{{·}}distant [1] | orbit_ref = | epoch = 27 April 2019 (JD 2458600.5) | uncertainty = 2 | observation_arc = 2.54 yr (927 d) | aphelion = 45.404 AU | perihelion = 2.4021 AU | semimajor = 23.903 AU | eccentricity = 0.8995 | period = 116.87 yr (42,686 d) | mean_anomaly = 59.873° | mean_motion = {{Deg2DMS|0.0084|sup=ms}} / day | inclination = 160.43° | asc_node = 297.77° | arg_peri = 103.13° | jupiter_moid = 0.1907 AU | tisserand = -1.5470 | mean_diameter = {{val|14|3|ul=km}}[4][9] | rotation = | albedo = {{val|0.03|0.01}}[4][9] | spectral_type = | abs_magnitude = 13.8[1] }}20461 Dioretsa ({{IPAc-en|d|aɪ|.|ə|ˈ|r|ɛ|t|s|ə}} {{respell|dy-ə|RET|sə}}), provisional designation {{mp|1999 LD|31}}, is a centaur and damocloid on a retrograde, cometary-like orbit from the outer Solar System. It was discovered on 8 June 1999, by members of the LINEAR team at the Lincoln Laboratory Experimental Test Site near Socorro, New Mexico, United States.[1] The highly eccentric unusual object measures approximately {{convert|14|km|mi|abbr=off|sigfig=2|sp=us}} in diameter.[4][9] It was named Dioretsa, the word "asteroid" spelled backwards.[1] Classification and orbitDioretsa is a member of the damocloids,[4] with a retrograde orbit and a negative TJupiter of −1.547. It is also a centaur, as its orbit has a semi-major axis in between that of Jupiter (5.5 AU) Neptune (30.1 AU). The Minor Planet Center lists it as a critical object and (other) unusual minor planet due to an orbital eccentricity of more than 0.5.[5]It orbits the Sun at a distance of 2.4–45.4 AU once every 116 years and 10 months (42,686 days; semi-major axis of 23.9 AU). Its orbit has an eccentricity of 0.90 and an inclination of 160° with respect to the ecliptic. Its observation arc begins 12 months prior to its official discovery observation, with a precovery taken by Spacewatch at Steward Observatory in June 1998.[1] Currently, its orbit still has an uncertainty of 2. Retrograde orbitAn inclination of greater than 90° means that a body moves in a retrograde orbit. Dioretsa{{'}}s orbit is otherwise similar to that of a comet. This has led to speculation that Dioretsa was originally an object from the Oort cloud.{{citation needed|date=June 2017}} NamingThe minor planet's name "Dioretsa" is the word "asteroid" spelled backwards, and is the first numbered of currently 99 known minor planets with a retrograde motion in the Solar System.[2] The approved naming citation was published by the Minor Planet Center on 1 May 2003 ({{small|M.P.C. 48396}}).[25] Physical characteristicsAccording to observations made with the 10-meter Keck Telescope, Dioretsa measures 14 kilometers in diameter and its surface has a low albedo of 0.03.[9] It has an absolute magnitude of 13.8. As of 2018, Dioretsa{{'}}s spectral type as well as its rotation period and shape remain unknown.[29] References1. ^1 2 {{cite book |title = Dictionary of Minor Planet Names – (20461) Dioretsa, Addendum to Fifth Edition: 2003–2005 |last = Schmadel | first = Lutz D. |publisher = Springer Berlin Heidelberg |page = 152 |date = 2006 |isbn = 978-3-540-34360-8 |doi = 10.1007/978-3-540-34361-5_1728 |chapter = (20461) Dioretsa [24.4, 0.90, 160.2] }} [1][2][3][4][5][6][7]2. ^1 2 3 4 5 6 {{cite web |title = 20461 Dioretsa (1999 LD31) |work = Minor Planet Center |url = https://www.minorplanetcenter.net/db_search/show_object?object_id=20461 |accessdate = 20 November 2018}} 3. ^1 {{cite web |title = MPC/MPO/MPS Archive |work = Minor Planet Center |url = https://www.minorplanetcenter.net/iau/ECS/MPCArchive/MPCArchive_TBL.html |accessdate = 20 November 2018}} 4. ^1 2 {{cite web |title = List Of Other Unusual Objects |work = Minor Planet Center |date = 14 November 2018 |url = https://www.minorplanetcenter.net/iau/lists/t_others.html |accessdate = 20 November 2018}} 5. ^1 2 3 4 5 {{cite web |title = List of Known Trans-Neptunian Objects |work = Johnston's Archive |date = 7 October 2018 |last = Johnston |first= Wm. Robert |url = http://www.johnstonsarchive.net/astro/tnoslist.html |accessdate = 20 January 2018}} 6. ^1 2 3 4 {{cite journal |display-authors = 6 |first1 = Alan W. |last1 = Harris |first2 = Marco |last2 = Delbó |first3 = Richard P. |last3 = Binzel |first4 = John K. |last4 = Davies |first5 = Julie |last5 = Roberts |first6 = David J. |last6 = Tholen |first7 = Robert J. |last7 = Whiteley |date = October 2001 |title = Visible to Thermal-Infrared Spectrophotometry of a Possible Inactive Cometary Nucleus |url = http://adsabs.harvard.edu/cgi-bin/bib_query?bibcode=2001Icar..153..332H |journal = Icarus |volume = 153 |issue = 2 |pages = 332–337 |bibcode = 2001Icar..153..332H |doi = 10.1006/icar.2001.6687 |access-date= 4 April 2016}} 7. ^1 {{cite web |title = LCDB Data for (20461) Dioretsa |publisher = Asteroid Lightcurve Database (LCDB) |url = http://www.minorplanet.info/PHP/GenerateALCDEFPage_Local.php?AstInfo=20461%7CDioretsa |accessdate = 27 June 2017}} }} External links
6 : Centaurs (minor planets)|Damocloids|Unusual minor planets|Discoveries by LINEAR|Named minor planets|Astronomical objects discovered in 1999 |
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