52 Europa

For the moon of Jupiter, see Europa (moon).
For other uses, see Europa (disambiguation).
52 Europa

3D model of Europa based on lightcurve modeling
Discovery
Discovered by H. Goldschmidt
Discovery date February 4, 1858
Designations
Pronunciation /jʊˈroʊpə/ ew-ROH-pə
Named after
 Europa
1948 LA
Main belt
Orbital characteristics
Epoch November 26, 2005 (JD 2453700.5)
Aphelion 3.417 AU (511.201 Gm)
Perihelion 2.785 AU (416.621 Gm)
3.101 AU (463.911 Gm)
Eccentricity 0.102
5.46 yr (1994.629 d)
16.87 km/s
70.730°
Inclination 7.466°
128.992°
343.553°
Physical characteristics
Dimensions (379±16)×(330±8)×(249±10) km
(mean: 315±7 km)[1]
360×315×240 km[2][3]
Mass 3.27×1019 kg[4]
Mean density
 1.5 ± 0.4 g/cm³[1]
~0.14 m/s²
~0.2 km/s
0.2347 d[5]
Albedo 0.058[6]
Temperature ~173 K
max: 258K (−15 °C)[7]
Spectral type
 C-type asteroid
6.31

    52 Europa is the 6th-largest asteroid in the asteroid belt, having an average diameter of around 315 km. It is not round but is shaped like a triaxial ellipsoid of approximately 380x330x250 km.[1] It was discovered on February 4, 1858, by Hermann Goldschmidt from his balcony in Paris. It is named after Europa, one of Zeus's conquests in Greek mythology, a name it shares with Jupiter's moon Europa.

    Physical characteristics

    Europa is approximately the sixth largest asteroid by volume. Most likely it has a density of around 1.5 g/cm³, typical of C-type asteroids.[1] In 2007, James Baer and Steven R. Chesley estimated Europa to have a mass of (1.9±0.4)×1019 kg.[2] A more recent estimate by Baer suggests it has a mass of 3.27×1019 kg.[4]

    Europa is a very dark carbonaceous C-type, and is the second largest of this group. Spectroscopic studies have found evidence of olivines and pyroxenes on the surface,[8] and there is some indication that there may be compositional differences between different regions[9] It orbits close to the 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 5 and a half hours to 11 hours), despite numerous observations.[10] It has now been determined that Europa is a 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 coordinates (β, λ) = (70°, 55°) or (40°, 255°) with a 10° uncertainty.[11] 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.[12]

    Observations

    It has been found that the reputed cataclysmic variable star CV Aquarii, discovered in 1934, was actually a misidentification of 52 Europa.[13]

    References

    1. 1 2 3 4 Merline, W.J. (2013). "The Resolved Asteroid Program - Size, shape, and pole of (52) Europa". arXiv:1301.5101.
    2. 1 2 Baer, James; Steven R. Chesley (2007). "Astrometric masses of 21 asteroids, and an integrated asteroid ephemeris" (PDF). Celestial Mechanics and Dynamical Astronomy (Springer Science+Business Media B.V. 2007) 100 (2008): 27–42. Bibcode:2008CeMDA.100...27B. doi:10.1007/s10569-007-9103-8. Retrieved 2008-11-15.
    3. ↑ http://www.rni.helsinki.fi/~mjk/Micha.pdf
    4. 1 2 Baer, James (2008). "Recent Asteroid Mass Determinations". Personal Website. Retrieved 2008-11-29.
    5. ↑ http://www.psi.edu/pds/archive/lc.html
    6. ↑ Tedesco, Edward F.; Noah, Paul V.; Noah, Meg; Price, Stephan D. (2002). "The Supplemental IRAS Minor Planet Survey". The Astronomical Journal (The American Astronomical Society) 123 (2): 1056–85. Bibcode:2002AJ....123.1056T. doi:10.1086/338320. ISSN 1538-3881.
    7. ↑ http://aa.springer.de/papers/0358003/2301133.pdf
    8. ↑ Dotto, E. (2000). "ISO results on bright Main Belt asteroids: PHT–S observations" (PDF). Astronomy & Astrophysics 358: 1133. Bibcode:2000A&A...358.1133D.
    9. ↑ http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=1991PhDT.......105S&db_key=AST&data_type=HTML&format=&high=444b66a47d24766
    10. ↑ Zappalà, V.; di Martino, M.; Cacciatori, S (1983). "On the ambiguity of rotational periods of asteroids: The peculiar case of 52 Europa". Icarus 56: 319–324. Bibcode:1983Icar...56..319Z. doi:10.1016/0019-1035(83)90041-6.
    11. ↑ Michałowski, T (2004). "Photometry and models of selected main belt asteroids I. 52 Europa, 115 Thyra, and 382 Dodona" (PDF). Astronomy & Astrophysics 416: 353–366. Bibcode:2004A&A...416..353M. doi:10.1051/0004-6361:20031706.
    12. ↑ Gradie, J.; Flynn, L. (March 1988), "A Search for Satellites and Dust Belts Around Asteroids: Negative Results", Abstracts of the Lunar and Planetary Science Conference 19, pp. 405–406, Bibcode:1988LPI....19..405G.
    13. ↑ http://www.aavso.org/publications/ejaavso/v28n2/103.pdf

    Bibliography

    External links

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