View source for 52 Europa

{{Short description|Large asteroid in the asteroid belt}}
{{for-multi|the moon of [[Jupiter]]|Europa (moon)|other uses|Europa (disambiguation)}}
{{Use dmy dates|date=January 2020}}
{{Infobox planet
| minorplanet=yes
| background=#D6D6D6
| name=52 Europa
| symbol =
| image = 52 Europa VLT (2021), deconvolved.pdf
| image_size = 
| caption = 
| discoverer=[[Hermann Mayer Salomon Goldschmidt|H. Goldschmidt]]
| discovered=4 February 1858
| mpc_name=(52) Europa
| alt_names=1948 LA
| pronounced ={{IPAc-en|j|ʊ|ˈ|r|oʊ|p|ə}}<ref>Noah Webster (1884) ''A Practical Dictionary of the English Language''</ref>
| adjective = Europan, Europian
| named_after = [[Europa (mythology)|Europa]]
| mp_category=[[Asteroid belt|Main belt]]
| orbit_ref = <ref name=JPL>[https://ssd.jpl.nasa.gov/sbdb.cgi?sstr=Europa JPL data] Retrieved 2021-09-29</ref>
| epoch=July 01, 2021 <br />([[Julian day|JD]] 2459396.5, heliocentric)
| semimajor=3.095 AU (460 Gm)
| perihelion=2.75 AU (420 Gm)
| aphelion=3.444 [[Astronomical unit|AU]] (510 Gm)
| eccentricity=0.111
| period=5.45 [[Julian year (astronomy)|yr]] (1989 d)
| inclination=7.48°
| asc_node=129°
| arg_peri=343°
| mean_anomaly=21°
| dimensions = (379±16)×(330±8)×(249±10) km<ref name="Merline" />
| flattening = 0.33{{efn|1=Flattening derived from the maximum aspect ratio (c/a): <math>f=1-\frac{c}{a}</math>, where (c/a) = {{val|.67|.04}}.<ref name=VLT/>}}
| mean_diameter={{val|319|4|u=km}}<ref name=VLT>P. Vernazza et al. (2021) VLT/SPHERE imaging survey of the largest main-belt asteroids: Final results and synthesis. ''Astronomy & Astrophysics'' 54, A56</ref><br />{{val|315|7|u=km}}<ref name="Merline" />
| mass={{val|24|4|e=18|u=kg}}<ref name=VLT/><br />{{val|22.6|1.6|e=18|u=kg}}{{refn|group=lower-alpha|(11.39 ± 0.79) × 10<sup>−12</sup> {{Solar mass}}}}<ref name="Baer2011">James Baer, Steven Chesley & Robert Matson (2011) "Astrometric masses of 26 asteroids and observations on asteroid porosity." ''The Astronomical Journal'', Volume 141, Number 5</ref>
| density={{val|1.41|.23|u=g/cm3}}<ref name=VLT/><br />{{val|1.5|0.4|u=g/cm3}}<ref name=Merline />
| rotation=5.6304 h<ref name=JPL/>
| spectral_type=[[C-type asteroid|C]]/[[CF-type asteroid|CF]]<ref name=JPL/>
| abs_magnitude=6.66<ref name=JPL/>
| albedo={{val|0.057|.007}} geometric ({{val|0.679|0.017}} BV, {{val|0.338|0.028}} UB)<ref name=JPL/>
| single_temperature=~173 [[kelvin|K]]<br />''max:'' 258K (−15&nbsp;°C)<ref>{{cite journal |last1=Dotto |first1=E. |last2=Müller |first2=T. G. |last3=Barucci |first3=M. A. |last4=Encrenaz |first4=Th. |last5=Knacke |first5=R. F. |last6=Lellouch |first6=E. |last7=Doressoundiram |first7=A. |last8=Crovisier |first8=J. |last9=Brucato |first9=J. R. |last10=Colangeli |first10=L. |last11=Mennella |first11=V. |author-link3=Maria A. Barucci|author-link4=Thérèse Encrenaz|author-link7=Alain Doressoundiram|author-link8=Crovisier|title=ISO results on bright Main Belt asteroids: PHT-S observations |journal=[[Astronomy and Astrophysics]] |date=2000 |volume=358 |page=1134 |url=https://ui.adsabs.harvard.edu/abs/2000A%26A...358.1133D/abstract |bibcode=2000A&A...358.1133D|access-date=23 February 2024}}</ref>
}}

'''52 Europa''' is the [[List of exceptional asteroids|sixth largest]] [[asteroid]] in the [[asteroid belt]], having a diameter of over 300&nbsp;km, though it is not correspondingly massive. It is not round but is shaped like an ellipsoid of approximately 380×330×250&nbsp;km.<ref name="Merline">{{Cite journal|last=Merline|first=W.J.|author-link=W.J. Merline|date=2013|title=The Resolved Asteroid Program – Size, shape, and pole of (52) Europa|journal=Icarus|volume=225|issue=1|pages=794–805|arxiv=1301.5101|bibcode=2013Icar..225..794M|doi=10.1016/j.icarus.2013.01.010|s2cid=119286695}}</ref> It was discovered on 4 February 1858, by [[Hermann Goldschmidt]] from his balcony in [[Paris]]. It is named after [[Europa (mythology)|Europa]], one of [[Zeus]]'s conquests in [[Greek mythology]], a name it shares with [[Jupiter]]'s moon [[Europa (moon)|Europa]].

==Physical characteristics==
[[file: 52 Europa Lightcurve Inversion.png|thumb|left|3D model of ''Europa'' based on [[lightcurve]] modeling]]
Europa is approximately the sixth largest asteroid by volume. Most likely it has a density of around 1.5 g/cm<sup>3</sup>, typical of C-type asteroids.<ref name=Merline/> In 2007, James Baer and Steven R. Chesley estimated Europa to have a mass of {{val|1.9|0.4|e=19}}&nbsp;kg.<ref name="Baer2007">{{cite journal
  |first=James |last=Baer |author-link=James Baer
  |author2=Steven R. Chesley
  |author2-link=Steven R. Chesley
  |title=Astrometric masses of 21 asteroids, and an integrated asteroid ephemeris
  |journal=Celestial Mechanics and Dynamical Astronomy
  |volume=100 |issue=2008 |pages=27–42
  |publisher=Springer Science+Business Media B.V. 2007
|doi=10.1007/s10569-007-9103-8
  |date=2007 |bibcode = 2008CeMDA.100...27B |doi-access=free}}</ref> A more recent estimate by Baer suggests it has a mass of 3.27{{e|19}} kg.<ref name=Baer>
{{cite web
  |date=2008
  |title=Recent Asteroid Mass Determinations
  |publisher=Personal Website
  |first=James
  |last=Baer
  |url=http://home.earthlink.net/~jimbaer1/astmass.txt
  |access-date=29 November 2008
  |archive-url=https://web.archive.org/web/20130702212735/http://home.earthlink.net/~jimbaer1/astmass.txt
  |archive-date=2 July 2013
  |url-status=dead
  }}
</ref>

Europa is a very dark carbonaceous [[C-type asteroid|C-type]], and is the second largest of this group. Spectroscopic studies have found evidence of [[olivine]]s and [[pyroxene]]s on the surface,<ref name=Dotto00 /> and there is some indication that there may be compositional differences between different regions.<ref>{{cite journal|title=A High-Resolution CCD Spectroscopic Survey of Low-Albedo Main Belt Asteroids.|first=Scott Raleigh|last=Sawyer|date=1 January 1991|journal=PhD Thesis|via=NASA ADS|bibcode=1991PhDT.......105S}}</ref> It orbits close to the [[Hygiea family|Hygiea asteroid family]], but is not a member.

[[Lightcurve]] data for Europa have been particularly tricky to interpret, so much so that for a long time its period of rotation was in dispute (ranging from {{frac|5|1|2}} hours to 11 hours), despite numerous observations.<ref name=Zappala83 /> It has now been determined that Europa is a [[Retrograde motion|prograde]] rotator, but the exact direction in which its pole points remains ambiguous. The most detailed analysis indicates that it points either towards about [[ecliptic coordinate system|ecliptic coordinates]] (β, λ) = (70°, 55°) or (40°, 255°) with a 10° uncertainty.<ref name=Michalowski04 /> This gives an [[axial tilt]] of about 14° or 54°, respectively.

In 1988 a search for satellites or dust orbiting this asteroid was performed using the [[UH88]] telescope at the [[Mauna Kea Observatories]], but the effort came up empty.<ref name="Gradie1988">{{Citation
 | last1     = Gradie
 | first1    = J.
 | last2     = Flynn
 | first2    = L.
 | title     = A Search for Satellites and Dust Belts Around Asteroids: Negative Results
 | work      = Abstracts of the Lunar and Planetary Science Conference
 | volume    = 19
 | pages     = 405–406
 |date=March 1988
 | bibcode   = 1988LPI....19..405G
 | postscript= .
}}</ref>

==Observations==
It has been found that the reputed [[cataclysmic variable]] star [[CV Aquarii]], discovered in 1934, was actually a misidentification of 52 Europa.<ref>{{cite web|url=http://www.aavso.org/publications/ejaavso/v28n2/103.pdf |title=CV Aquarii identified with (52) Europa|access-date=29 April 2006 |url-status=dead |archive-url=https://web.archive.org/web/20060214091638/http://www.aavso.org/publications/ejaavso/v28n2/103.pdf |archive-date=14 February 2006 }}</ref>
[[File:Animation of 52 Europa orbit 2000-2020.gif|thumb|left|Animation of 52 Europa{{'s}} orbit 2000–2020<br />{{legend2| yellow| Sun}}{{legend2| RoyalBlue| Earth}}{{·}}{{legend2| Gold| Mars}}{{·}}{{legend2| Lime|Jupiter}}{{·}}{{legend2| Magenta| 52 Europa}}]]
{{clear}}

== Notes ==
{{notelist}}

== References ==
{{reflist|refs=

<!-- Not in use
<ref name=IRAS>{{cite journal
  |title = The Supplemental IRAS Minor Planet Survey
  |last1 = Tedesco
  |first1 = Edward F.
  |last2 = Noah
  |first2 = Paul V.
  |last3 = Noah
  |first3 = Meg
  |last4 = Price
  |first4 = Stephan D.
  |journal = [[The Astronomical Journal]]
  |publisher = [[The American Astronomical Society]]
  |issn = 1538-3881
  |volume = 123
  |issue = 2
  |year = 2002
  |pages = 1056–85
  |doi = 10.1086/338320
|bibcode = 2002AJ....123.1056T |doi-access = free
  }}</ref>
Not in use-->

<ref name=Michalowski04>{{cite journal |last1=Michałowski |first1=T |url=http://www.rni.helsinki.fi/~mjk/Micha.pdf  |title=Photometry and models of selected main belt asteroids I. 52 Europa, 115 Thyra, and 382 Dodona | journal=Astronomy & Astrophysics |volume=416 |pages=353–366 |year=2004|bibcode = 2004A&A...416..353M |doi = 10.1051/0004-6361:20031706 |doi-access=free }}</ref>

<ref name=Dotto00>{{cite journal |last1=Dotto |first1=E. |url=http://aa.springer.de/papers/0358003/2301133.pdf |title=ISO results on bright Main Belt asteroids: PHT–S observations |journal=Astronomy & Astrophysics |volume=358 |page=1133 |year=2000 |bibcode=2000A&A...358.1133D |access-date=29 April 2006 |archive-url=https://web.archive.org/web/20050514163258/http://aa.springer.de/papers/0358003/2301133.pdf |archive-date=14 May 2005 |url-status=dead }}</ref>

<ref name=Zappala83>{{cite journal |last1=Zappalà |first1=V. |first2=M. |last2=di Martino |first3=S |last3=Cacciatori |title=On the ambiguity of rotational periods of asteroids: The peculiar case of 52 Europa |journal=Icarus |volume=56 |issue=2 |pages=319–324 |year=1983|bibcode = 1983Icar...56..319Z |doi = 10.1016/0019-1035(83)90041-6 }}</ref>

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

== Bibliography ==
* [https://archive.today/20060614093519/http://www.psi.edu/pds/archive/lc.html PDS lightcurve data]
* {{cite thesis |last1=Sawyer |first1=S. R. |title=A High-Resolution CCD Spectroscopic Survey of Low-Albedo Main Belt Asteroids PhD thesis |publisher=The University of Texas |year=1991|bibcode=1991PhDT.......105S }}
* Schmeer, P., and M. L. Hazen, ''[https://web.archive.org/web/20060214091638/http://www.aavso.org/publications/ejaavso/v28n2/103.pdf CV Aquarii identified with (52) Europa]'', Journal of the American Association of Variable Star Observers, Vol. 28, p.&nbsp;103 (2000).

== External links ==
* {{cite web | title=Elements and Ephemeris for (52) Europa | url=http://scully.cfa.harvard.edu/cgi-bin/returnprepeph.cgi?d=b2011&o=00052 | access-date=26 May 2011 | url-status=dead | archive-url=https://web.archive.org/web/20160304051741/http://scully.cfa.harvard.edu/cgi-bin/returnprepeph.cgi?d=b2011&o=00052 | archive-date=4 March 2016 }}
* [http://www.rni.helsinki.fi/~mjk/Micha.pdf shape model deduced from lightcurve]
* {{AstDys|52}}
* {{JPL small body}}

{{Minor planets navigator |51 Nemausa |number=52 |53 Kalypso}}
{{Large asteroids}}
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{{DEFAULTSORT:000052}}
[[Category:Discoveries by Hermann Goldschmidt|Europa]]
[[Category:Named minor planets|Europa]]
[[Category:CF-type asteroids (Tholen)]]
[[Category:C-type asteroids (SMASS)]]
[[Category:Astronomical objects discovered in 1858|18580204]]