Star field showing asteroid Europa
|Discovered by||H. Goldschmidt|
|Discovery date||February 4, 1858|
|Alternative names||1948 LA|
|Minor planet category||Main belt|
|Epoch November 26, 2005 (JD 2453700.5)|
|Aphelion||3.417 AU (511.201 Gm)|
|Perihelion||2.785 AU (416.621 Gm)|
|Semi-major axis||3.101 AU (463.911 Gm)|
|Orbital period||5.46 a (1994.629 d)|
|Average orbital speed||16.87 km/s|
|Longitude of ascending node||128.992°|
|Argument of perihelion||343.553°|
|Mean density||1.5 ± 0.4 g/cm³|
|Equatorial surface gravity||~0.14 m/s²|
|Escape velocity||~0.2 km/s|
|Rotation period||0.2347 d |
max: 258K (-15 °C)
|Spectral type||C-type asteroid|
|Absolute magnitude (H)||6.31|
52 Europa is one of the larger asteroids in the asteroid belt, having an average diameter of around 315 km. The body is not round but is shaped like a triaxial ellipsoid of approximately 380x330x250 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.
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. In 2007, James Baer and Steven R. Chesley estimated Europa to have a mass of (1.9±0.4)×1019 kg. A more recent estimate by Baer suggests it has a mass of 3.27×1019 kg.
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, and there is some indication that there may be compositional differences between different regions 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. 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.. This gives an axial tilt of about 14° or 54°, respectively.
- 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.
- Merline, W.J.; and many others (2013). The Resolved Asteroid Program - Size, shape, and pole of (52) Europa (PDF). Retrieved 2013-01-24.
- Baer, James (2008). "Recent Asteroid Mass Determinations". Personal Website. Retrieved 2008-11-29.
- 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: 405–406, Bibcode:1988LPI....19..405G.
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
Dotto, E., et al. ISO results on bright Main Belt asteroids: PHT–S observations, Astronomy & Astrophysics, Vol. 358, p. 1133 (2000).
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).
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).