52 Europa

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52 Europa
Discovery
Discovered by H. Goldschmidt
Discovery date February 04, 1858
Designations
Alternative names 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°
Physical characteristics
Dimensions 360×315×240 km[1][2]
Mass 5.2±1.8×1019 kg[3]
Mean density 3.6±1.2 g/cm³
Equatorial surface gravity ~0.11 m/s²
Escape velocity ~0.20 km/s
Rotation period 0.2347 d [4]
Albedo 0.058 [1]
Temperature ~173 K
max: 258K (-15 °C)[5]
Spectral type C-type asteroid
Absolute magnitude 6.31


52 Europa (pronounced /jʊˈroʊpə/) is an asteroid. It has a diameter of 301 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 the seventh largest asteroid by volume and the sixth largest by mass (after Ceres, Vesta, Pallas, Hygiea, and Interamnia) and contains somewhat less than 2% of the mass of the entire main belt.

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[6]

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 (β, λ) = (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 reputed cataclysmic variable star CV Aquarii found in 1934, was actually a false misidentification of 52 Europa[7].

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


[edit] References

  2. T. Michałowski 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).
  4. PDS lightcurve data
  5. E. Dotto et al ISO results on bright Main Belt asteroids: PHT–S observations, Astronomy & Astrophysics, Vol. 358, p. 1133 (2000).
  6. S.R. Sawyer A High-Resolution CCD Spectroscopic Survey of Low-Albedo Main Belt Asteroids, PhD thesis, The University of Texas (1991).
  7. P. Schmeer and M.L. Hazen CV Aquarii identified with (52) Europa, Journal of the American Association of Variable Star Observers, Vol. 28, p. 103 (2000).
  8. V. Zappalà, 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

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