52 Europa ( ) is one of the larger asteroids. It has a diameter of 300 km, and was discovered on February 4, 1858 by H. Goldschmidt. It is named after Europa, one of Zeus's conquests in Greek mythology. Europa is approximately the seventh largest asteroid by volume, though it has a low density (is highly porous), presumably through having suffered a particularly severe collision.^[1]

It is a very dark carbonaceous C-type, and the fourth-largest of these. It orbits close to the Hygiea asteroid family, but is not a member. 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^{http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=1991PhDT.......105S&db_key=AST&data_type=HTML&format=&high=444b66a47d24766}

Lightcurve data for Europa has been particularly tricky to interpret, so much so for a long time its period of rotation was in dispute (5 and a half, or 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 (?, ?) = (70°, 55°) or (40°, 255°) with a 10° uncertainty ^[2]. This gives an axial tilt of about 14° or 54°, respectively.

It has been found that the reputed cataclysmic variable star CV Aquarii, discovered in 1934, was actually a misidentification of 52 Europa^{http://www.aavso.org/publications/ejaavso/v28n2/103.pdf}.

52 Europa should not be confused with Jupiter's moon Europa.

Mass

In 2001, Michalak estimated Europa to have a mass of (5.2±1.8) kg.^[2] In 2007, Baer and Chesley estimated Europa to have a mass of (1.9±0.4) kg.^[1] A more recent estimate by Baer suggests it has a mass of 1.65 kg.^[3]

Footnotes

1. ↑ ^{a b}
2. ↑
3. ↑

References

1. IRAS Minor Planet Survey
2. Micha?owski, 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).
3. PDS lightcurve data
4. Dotto, E., et al. ISO results on bright Main Belt asteroids: PHT?S observations, Astronomy & Astrophysics, Vol. 358, p. 1133 (2000).
5. Sawyer, S. R., A High-Resolution CCD Spectroscopic Survey of Low-Albedo Main Belt Asteroids, PhD thesis, The University of Texas (1991).
6. 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).
7. Zappalą, 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).

External links

• shape model deduced from lightcurve

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