Astronomy:52 Europa

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52 Europa
VLT-SPHERE image of Europa
Discovery
Discovered byH. Goldschmidt
Discovery date4 February 1858
Designations
(52) Europa
Pronunciation/jʊˈroʊpə/[1]
Named afterEuropa
1948 LA
Minor planet categoryMain belt
AdjectivesEuropan, Europian
Orbital characteristics[2]
Epoch July 1, 2021
(JD 2,459,396.5, heliocentric)
|{{{apsis}}}|helion}}3.442 AU (515 million km)*
|{{{apsis}}}|helion}}2.746 AU (411 million km)
3.094 AU (463 million km)
Eccentricity0.1125
Orbital period5.443 yr (1989 d)
Mean anomaly21°
Inclination7.48°
Longitude of ascending node128.57°
342.80°
Physical characteristics
Dimensions(379±16)×(330±8)×(249±10) km[3]
Mean diameter319±4 km[4]
315±7 km[3]
Flattening0.33[lower-alpha 1]
Mass(24±4)×1018 kg[4]
(22.6±1.6)×1018 kg[lower-alpha 2][5]
Mean density1.41±0.23 g/cm3[4]
1.5±0.4 g/cm3[3]
Rotation period5.6304 h[2]
Geometric albedo0.057±0.007 geometric (0.679±0.017 BV, 0.338±0.028 UB)[2]
C/CF[2]
Absolute magnitude (H)6.66[2]


52 Europa is the sixth-largest asteroid in the asteroid belt, having a diameter of over 300 km, though it is not correspondingly massive. It is shaped like an ellipsoid with approximate dimensions of 380×330×250 km.[3] It was discovered on 4 February 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.

Orbit

Animation of 52 Europa's orbit 2000–2020
  Sun ·   Earth ·   Mars ·   Jupiter ·   52 Europa

Europa is a main belt asteroid that orbits the Sun at a distance of 2.746–3.442 astronomical units (AU) with a semi-major axis or average orbital distance of 3.094 AU once every 5.44 years[2] (for reference, Ceres's orbit is at 2.77 AU).[6]

Europa's orbit has an eccentricity of 0.1125 and an inclination of 7.482° with respect to the ecliptic.[2]

Physical characteristics

3D model of Europa based on lightcurve modeling

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.[3] In 2007, James Baer and Steven R. Chesley estimated Europa to have a mass of (1.9±0.4)×1019 kg.[7] A more recent estimate by Baer suggests it has a mass of 3.27×1019 kg.[8]

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,[9] and there is some indication that there may be compositional differences between different regions.[10] It orbits close to the Hygiea asteroid family, but is not a member.

Lightcurve data for Europa have been particularly tricky to interpret, so much so that for a long time its period of rotation was in dispute (ranging from ​5 1⁄2 hours to 11 hours), despite numerous observations.[11] 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.[12] This gives an axial tilt of about 14° or 54°, respectively.

In 1988 a search for satellites or dust orbiting this asteroid was performed using the UH88 telescope at the Maunakea Observatories, but the effort came up empty.[13]

Observations

The reputed cataclysmic variable star CV Aquarii, discovered in 1934 by Emily Hughes at Harvard College Observatory, was actually a misidentification of 52 Europa.[14]

Notes

  1. ↑ Flattening derived from the maximum aspect ratio (c/a): f=1−ca, where (c/a) = 0.67±0.04.[4]
  2. ↑ (11.39 ± 0.79) × 10−12 M☉

References

  1. ↑ Webster, Noah (1884). A Practical Dictionary of the English Language
  2. ↑ 2.0 2.1 2.2 2.3 2.4 2.5 2.6 JPL data Retrieved 2021-09-29
  3. ↑ 3.0 3.1 3.2 3.3 3.4 Merline, W.J. (2013). "The Resolved Asteroid Program – Size, shape, and pole of (52) Europa". Icarus 225 (1): 794–805. doi:10.1016/j.icarus.2013.01.010. Bibcode: 2013Icar..225..794M. 
  4. ↑ 4.0 4.1 4.2 4.3 P. Vernazza et al. (2021) VLT/SPHERE imaging survey of the largest main-belt asteroids: Final results and synthesis. Astronomy & Astrophysics 54, A56
  5. ↑ James Baer, Steven Chesley & Robert Matson (2011) "Astrometric masses of 26 asteroids and observations on asteroid porosity." The Astronomical Journal, Volume 141, Number 5
  6. ↑ "AstDyS-2 Ceres Synthetic Proper Orbital Elements". Department of Mathematics, University of Pisa, Italy. https://newton.spacedys.com/astdys/index.php?pc=1.1.6&n=1. 
  7. ↑ Baer, James; Chesley, Steven R. (2007). "Astrometric masses of 21 asteroids, and an integrated asteroid ephemeris". Celestial Mechanics and Dynamical Astronomy (Springer Science+Business Media B.V. 2007) 100 (2008): 27–42. doi:10.1007/s10569-007-9103-8. Bibcode: 2008CeMDA.100...27B. 
  8. ↑ Baer, James (2008). "Recent Asteroid Mass Determinations". Personal Website. http://home.earthlink.net/~jimbaer1/astmass.txt. 
  9. ↑ Dotto, E. (2000). "ISO results on bright Main Belt asteroids: PHT–S observations". Astronomy & Astrophysics 358: 1133. Bibcode: 2000A&A...358.1133D. http://aa.springer.de/papers/0358003/2301133.pdf. Retrieved 29 April 2006. 
  10. ↑ Sawyer, Scott Raleigh (1 January 1991). "A High-Resolution CCD Spectroscopic Survey of Low-Albedo Main Belt Asteroids.". PhD Thesis. Bibcode: 1991PhDT.......105S. 
  11. ↑ Zappalà, V.; di Martino, M.; Cacciatori, S (1983). "On the ambiguity of rotational periods of asteroids: The peculiar case of 52 Europa". Icarus 56 (2): 319–324. doi:10.1016/0019-1035(83)90041-6. Bibcode: 1983Icar...56..319Z. 
  12. ↑ Michałowski, T (2004). "Photometry and models of selected main belt asteroids I. 52 Europa, 115 Thyra, and 382 Dodona". Astronomy & Astrophysics 416: 353–366. doi:10.1051/0004-6361:20031706. Bibcode: 2004A&A...416..353M. http://www.rni.helsinki.fi/~mjk/Micha.pdf. 
  13. ↑ 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: pp. 405–406, Bibcode: 1988LPI....19..405G. 
  14. ↑ Schmeer, Patrick; Hazen, Martha L.. "CV Aquarii identified with (52) Europa". Journal of the American Association of Variable Star Observers 28: 103–105. Bibcode: 2000JAVSO..28..103S. http://www.aavso.org/publications/ejaavso/v28n2/103.pdf. Retrieved 29 April 2006. 

Bibliography

  • Template:Deprecated archive
  • Sawyer, S. R. (1991). A High-Resolution CCD Spectroscopic Survey of Low-Albedo Main Belt Asteroids PhD thesis (Thesis). The University of Texas. Bibcode:1991PhDT.......105S.
  • 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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