54 Alexandra

{{Short description|Main-belt asteroid}} {{Use dmy dates|date=July 2018}} {{Infobox planet | minorplanet = yes | background = #D6D6D6 | name = 54 Alexandra | image = 54 Alexandra.png | image_scale = | caption = A three-dimensional model of 54 Alexandra based on its light curve (top) and images of the asteroid (bottom) | discovery_ref = <ref name=jpldata/> | discoverer = H. Goldschmidt | discovered = 10 September 1858 | mpc_name = (54) Alexandra | alt_names = | pronounced = {{IPAc-en|ˌ|æ|l|ᵻ|g|'|z|æ|n|d|r|ə|,_|-|'|z|ɑː|n|-}} {{respell|AL|ig|ZA(H)N|drə}}<ref>{{Cite encyclopedia |url=http://www.lexico.com/definition/Alexandra |archive-url=https://web.archive.org/web/20200322182812/https://www.lexico.com/definition/alexandra |url-status=dead |archive-date=22 March 2020 |title=Alexandra |dictionary=Lexico UK English Dictionary |publisher=Oxford University Press}}<br />{{dict.com|Alexandra}}</ref> | adjective = Alexandrian | named_after = {{nowrap|Alexander von Humboldt}}<br />{{small|(German explorer)}} | mp_category = Main belt | epoch = December 31, 2006 (JD 2454100.5) | semimajor = {{nowrap|405.763 million km (2.712 AU)}} | perihelion = {{nowrap|326.043 million km (2.179 AU)}} | aphelion = {{nowrap|485.483 million km (3.245 AU)}} | eccentricity = 0.196 | period = {{Convert|1631.620|day|year|sigfig=3|abbr=on|lk=out}} | inclination = 11.804° | asc_node = 313.446° | arg_peri = 345.594° | pole_ecliptic_lat = {{Val|17|4|u=°}}<ref name=Hanus2017/> | pole_ecliptic_lon = {{Val|155|3|u=°}}<ref name=Hanus2017/> | mean_anomaly = 103.809° | dimensions = 160 × 135 km (± 1 km) | mean_diameter = 154.137 km<ref name=jpldata/> | mass = {{val|6.16|3.50|e=18|u=kg}}<ref name="Carry2012"/> | density = {{val|3.50|2.11|u=g/cm3}}<ref name="Carry2012"/> | rotation = 18.14 h<ref name="Belskaya1993"/> | spectral_type = Tholen {{=}} C<ref name=jpldata/><br />SMASS {{=}} C<ref name=jpldata/> | abs_magnitude = 7.66<ref name=jpldata/> | albedo = 0.056<ref name=jpldata/><ref>{{Cite web |url=http://www.psi.edu/pds/resource/albedo.html |title=Asteroid Data Sets |access-date=12 January 2007 |archive-date=17 December 2009 |archive-url=https://web.archive.org/web/20091217104722/http://www.psi.edu/pds/resource/albedo.html |url-status=dead }}</ref> }}

'''54 Alexandra''' is a carbonaceous asteroid from the intermediate asteroid belt, approximately 155 kilometers in diameter. It was discovered by German-French astronomer Hermann Goldschmidt on 10 September 1858, and named after the German explorer Alexander von Humboldt; it was the first asteroid to be named after a male.<ref name="Schmadel2003"/>

== Description ==

On May 17, 2005, this asteroid occulted a faint star (magnitude 8.5) and the event was observed and timed in a number of locations within the U.S. and Mexico. As a result, a silhouette profile was produced, yielding a roughly oval cross-section with dimensions of 160 × 135 km (± 1 km).<ref>D.W. Dunham, "Upcoming Asteroid Occultations", ''Sky & Telescope'', June, 2006, p. 63.</ref> The mass of the asteroid can be estimated based upon the mutually perturbing effects of other bodies, yielding an estimate of {{Val|6.16|3.50|e=18|u=kg}}.<ref name="Carry2012"/>

Photometric observations of this asteroid during 1990–92 gave a light curve with a period of 18.14 ± 0.04 hours and a brightness variation of 0.10 in magnitude.<ref name="Belskaya1993"/> Alexandra has been studied by radar.<ref name="detected"/> It was the namesake and largest member of the former Alexandra asteroid family; a dynamic group of C-type asteroids that share similar orbital elements. Other members included 70 Panopaea and 145 Adeona.<ref name="Williams1988"/> 145 Adeona was subsequently assigned to the Adeona family, with Alexandra and Panopaea being dropped.<ref name="Zappala1990"/>

==In popular culture==

In the Swedish film ''Aniara'', 54 Alexandra is the closest celestial body which the off-course and out-of-control spacecraft will approach before it leaves the Solar System.

==References== {{Reflist|refs=

<ref name=jpldata>{{cite web | first1 = Donald K. | last1 = Yeomans | title = 54 Alexandra | work = JPL Small-Body Database Browser | publisher = NASA Jet Propulsion Laboratory | url = https://ssd.jpl.nasa.gov/sbdb.cgi?sstr=54 | access-date= 2013-04-07 }}</ref>

<ref name=Hanus2017>{{citation | postscript=. | title=Volumes and bulk densities of forty asteroids from ADAM shape modeling | last1=Hanuš | first1=J. | last2=Viikinkoski | first2=M. | last3=Marchis | first3=F. | last4=Ďurech | first4=J. | last5=Kaasalainen | first5=M. | last6=Delbo' | first6=M. | last7=Herald | first7=D. | last8=Frappa | first8=E. | last9=Hayamizu | first9=T. | last10=Kerr | first10=S. | last11=Preston | first11=S. | last12=Timerson | first12=B. | last13=Dunham | first13=D. | last14=Talbot | first14=J. | journal=Astronomy & Astrophysics | display-authors=1 | volume=601 | id=A114 | pages=41 | date=May 2017 | doi=10.1051/0004-6361/201629956 | bibcode=2017A&A...601A.114H | arxiv=1702.01996}}</ref>

<ref name="Schmadel2003">{{Citation | first1 = Lutz D. | last1 = Schmadel | title = Dictionary of Minor Planet Names | publisher = Springer | edition = 5th | page = 20 | date = 2003 | isbn = 3642297188 | url = https://books.google.com/books?id=KWrB1jPCa8AC&pg=PA20 | postscript= .}}</ref>

<ref name="Carry2012">{{Citation | first1 = B. | last1 = Carry | title = Density of asteroids | work = Planetary and Space Science | volume = 73 | pages = 98–118 |date=December 2012 | doi = 10.1016/j.pss.2012.03.009 | bibcode = 2012P&SS...73...98C | postscript= . |arxiv = 1203.4336 }} See Table 1.</ref>

<ref name="Belskaya1993">{{Citation | last1 = Belskaya | first1 = I. N. | last2 = Dovgopol | first2 = A. N. | last3 = Erikson | first3 = A. | last4 = Lagerkvist | first4 = C.-I. | last5 = Oja | first5 = T. | display-authors = 1 | title = Physical Studies of Asteroids. Part XXVII. Photoelectric Photometry of Asteroids 14 Irene, 54 Alexandra and 56 Melete | work = Astronomy and Astrophysics Supplement | volume = 101 | issue = 3 | pages = 507–511 |date=November 1993 | bibcode = 1993A&AS..101..507B | postscript= .}}</ref>

<ref name="Williams1988">{{Citation | first1 = J. G. | last1 = Williams | title = The Unusual Alexandra Family | work = Abstracts of the Lunar and Planetary Science Conference | volume = 19 | pages = 1277–1278 |date=March 1988 | bibcode = 1988LPI....19.1277W | postscript= .}}</ref>

<ref name="Zappala1990">{{Citation | last1 = Zappala | first1 = Vincenzo | last2 = Cellino | first2 = Alberto | last3 = Farinella | first3 = Paolo | last4 = Knezevic | first4 = Zoran | display-authors = 1 | title = Asteroid families. I - Identification by hierarchical clustering and reliability assessment | work = Astronomical Journal | volume = 100 | pages = 2030–2046, 2045 |date=December 1990 | doi = 10.1086/115658 | bibcode = 1990AJ....100.2030Z | postscript= . | doi-access= free }} See p. 2045 and family 44.</ref>

<ref name="detected">{{cite web | title=Radar-Detected Asteroids and Comets | publisher=NASA/JPL Asteroid Radar Research | url=http://echo.jpl.nasa.gov/asteroids/ | access-date=2011-10-30}}</ref>

}}

== External links == * {{usurped|1=[https://web.archive.org/web/20170321170056/http://www.minorplanetobserver.com/pdolc/A54_2008.HTM Lightcurve plot of 54 Alexandra]}}, Palmer Divide Observatory, ''B. D. Warner'' (2008) * [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 }}) * [https://books.google.com/books?id=aeAg1X7afOoC&pg Dictionary of Minor Planet Names], Google books * [http://obswww.unige.ch/~behrend/page_cou.html Asteroids and comets rotation curves, CdR] – Observatoire de Genève, Raoul Behrend * [https://www.minorplanetcenter.net/iau/lists/NumberedMPs000001.html Discovery Circumstances: Numbered Minor Planets (1)-(5000)] – Minor Planet Center * {{AstDys|54}} * {{JPL small body}}

{{DEFAULTSORT:Alexandra}} 000054 Category:Discoveries by Hermann Goldschmidt Category:Named minor planets 000054 000054 18580910