52 Europa
52 Europa is an asteroid. It has a diameter of 289 km, and was found on February 4, 1858 by H. Goldschmidt. It is named after Europa, one of Zeus's conquests in Greek mythology. Europa is the seventh biggest asteroid by volume and the sixth biggest by mass (after Ceres, Vesta, Pallas, Hygiea, and Interamnia) and contains somewhat less than 2% of the mass of the entire main belt.
 Europa as seen in 24 inch telescope | |
| Discovery | |
|---|---|
| Discovered by | H. Goldschmidt |
| Discovery date | February 04, 1858 |
| Designations | |
| 1948 LA | |
| Main belt | |
| Orbital characteristics | |
| Epoch November 26, 2005 (JD 2453700.5) | |
| Aphelion | 511.201 Gm (3.417 AU) |
| Perihelion | 416.621 Gm (2.785 AU) |
| 463.911 Gm (3.101 AU) | |
| Eccentricity | 0.102 |
| 1994.629 d (5.46 a) | |
Average orbital speed | 16.87 km/s |
| 70.730° | |
| Inclination | 7.466° |
| 128.992° | |
| 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 |
| ~0.11 m/s² | |
| ~0.20 km/s | |
| 0.2347 d [4] | |
| Albedo | 0.058 [1] |
| Temperature | ~173 K max: 258K (-15 °C)[5] |
Spectral type | C-type asteroid |
| 6.31 | |
It is a very dark carbonaceous C-type, and the fourth-biggest 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.
Lightcurve data for Europa has been very hard to interpret, so much so for a long time its period of rotation was in dispute (5 and a half, or 11 hours?) despite many observations[8]. It has now been determined that Europa is a prograde rotator, but the exact direction in which its pole points remains unclear. 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 the star CV Aquarii found in 1934, was actually an incorrect misidentification of 52 Europa[6] Archived 2006-02-14 at the Wayback Machine.
References
change- T. Michałowski et al. Photometry and models of selected main belt asteroids I. 52 Europa, 115 Thyra, and 382 Dodona Archived 2012-07-16 at the Wayback Machine, Astronomy & Astrophysics, Vol. 416, p. 353 (2004).
- G. Michalak Determination of asteroid masses II. (6) Hebe, (10) Hygiea, (15) Eunomia, (52) Europa, (88) Thisbe, (444) Gyptis, (511) Davida and (704) Interamnia Archived 2006-03-07 at the Wayback Machine, Astronomy & Astrophysics, Vol. 374, p. 703 (2001)
- PDS lightcurve data Archived 2006-06-14 at the Wayback Machine
- E. Dotto et al. ISO results on bright Main Belt asteroids: PHT – S observations Archived 2005-05-14 at the Wayback Machine, Astronomy & Astrophysics, Vol. 358, p. 1133 (2000).
- S.R. Sawyer A High-Resolution CCD Spectroscopic Survey of Low-Albedo Main Belt Asteroids, PhD thesis, The University of Texas (1991).
- P. Schmeer and M.L. Hazen CV Aquarii identified with (52) Europa Archived 2006-02-14 at the Wayback Machine, Journal of the American Association of Variable Star Observers, Vol. 28, p. 103 (2000).
- 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).
Other websites
change- "(52) Europa". CBAT/MPC/ICQ Index. Retrieved 2005-08-12.
- shape model deduced from lightcurve Archived 2012-07-16 at the Wayback Machine