52 Europa
Star field showing asteroid Europa
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Discovery
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| Discovered by | H. Goldschmidt |
| Discovery date | February 4, 1858 |
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Designations
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| Named after | Europa |
| Alternate name(s) | 1948 LA |
| Minor planet category |
Main belt |
| Epoch November 26, 2005 (JD 2453700.5) | |
| Aphelion | 511.201 Gm (3.417 AU) |
| Perihelion | 416.621 Gm (2.785 AU) |
| Semi-major axis | 463.911 Gm (3.101 AU) |
| Eccentricity | 0.102 |
| Orbital period | 1994.629 d (5.46 a) |
| Average orbital speed | 16.87 km/s |
| Mean anomaly | 70.730° |
| Inclination | 7.466° |
| Longitude of ascending node | 128.992° |
| Argument of perihelion | 343.553° |
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Physical characteristics
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| Dimensions | 360×315×240 km[1][1] 362×302×252 km[2] |
| Mass | 1.65×1019 kg[2] |
| Mean density | 1.14 ± 0.13 g/cm³[2] |
| Equatorial surface gravity | ~0.11 m/s² |
| Escape velocity | ~0.20 km/s |
| Rotation period | 0.2347 d [2] |
| Albedo | 0.058 [1] |
| Temperature | ~173 K max: 258K (-15 °C)[3] |
| Spectral type | C-type asteroid |
| Absolute magnitude (H) | 6.31 |
52 Europa (
/jʊˈroʊpə/ ew-ROH-pə) is one of the larger asteroids in the asteroid belt, having a diameter of 300 km. 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.
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[edit] Physical characteristics
Europa is approximately the seventh largest asteroid by volume. However, it has a low density (i.e. is highly porous), presumably through having suffered a particularly severe collision.[1] In 2001, Michalak estimated Europa to have a mass of (5.2±1.8)×1019 kg.[3] In 2007, James Baer and Steven R. Chesley estimated Europa to have a mass of (1.9±0.4)×1019 kg.[1] A more recent estimate by Baer suggests it has a mass of 1.65×1019 kg.[2]
Europa is a very dark carbonaceous C-type, and is the fourth largest of this group. Spectroscopic studies have found evidence of olivines and pyroxenes on the surface,[5] and there is some indication that there may be compositional differences between different regions[4] It orbits close to the Hygiea asteroid family, but is not a member.
Lightcurve data for Europa has 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.[8] 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.[2]. This gives an axial tilt of about 14° or 54°, respectively.
[edit] Observations
It has been found that the reputed cataclysmic variable star CV Aquarii, discovered in 1934, was actually a misidentification of 52 Europa.[5]
[edit] Footnotes
- ^ a b c 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. http://www.springerlink.com/content/h747307j43863228/fulltext.pdf. Retrieved 2008-11-15.
- ^ a b c d Baer, James (2008). "Recent Asteroid Mass Determinations". Personal Website. http://home.earthlink.net/~jimbaer1/astmass.txt. Retrieved 2008-11-29.
- ^ Michalak, G. (2001). "Determination of asteroid masses". Astronomy & Astrophysics 374: 703–711. Bibcode 2001A&A...374..703M. doi:10.1051/0004-6361:20010731. http://www.aanda.org/index.php?option=article&access=standard&Itemid=129&url=/articles/aa/abs/2001/29/aa10228/aa10228.html. Retrieved 2008-11-15.
[edit] References
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Michałowski, T., et al. Photometry and models of selected main belt asteroids I. 52 Europa, 115 Thyra, and 382 Dodona, Astronomy & Astrophysics, Vol. 416, p. 353 (2004).
- PDS lightcurve data
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Dotto, E., et al. ISO results on bright Main Belt asteroids: PHT–S observations, Astronomy & Astrophysics, Vol. 358, p. 1133 (2000).
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Sawyer, S. R., A High-Resolution CCD Spectroscopic Survey of Low-Albedo Main Belt Asteroids, PhD thesis, The University of Texas (1991).
- Schmeer, P., and M. L. Hazen, CV Aquarii identified with (52) Europa, Journal of the American Association of Variable Star Observers, Vol. 28, p. 103 (2000).
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Zappalà, V.; M. di Martino and S. Cacciatori On the ambiguity of rotational periods of asteroids: The peculiar case of 52 Europa, Icarus, Vol. 56, p. 319 (1983).
[edit] External links
- "Elements and Ephemeris for (52) Europa". http://scully.cfa.harvard.edu/cgi-bin/returnprepeph.cgi?d=b2011&o=00052. Retrieved 2011-05-26.
- shape model deduced from lightcurve
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