13 Egeria

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13 Egeria Astronomical symbol of 13 Egeria
13Egeria (Lightcurve Inversion).png
A three-dimensional model of 13 Egeria based on its light curve.
Discovered by Annibale de Gasparis
Discovery date November 2, 1850
Pronunciation /ɨˈɪəriə/ i-JEER-ee-ə
Main belt
Orbital characteristics[1]
Epoch July 14, 2004 (JD 2453200.5)
Aphelion 417.953 Gm (2.794 AU)
Perihelion 352.719 Gm (2.358 AU)
385.336 Gm (2.576 AU)
Eccentricity 0.085
1,509.977 d (4.13 a)
18.56 km/s
Inclination 16.540°
Physical characteristics
Dimensions 214.8×192[2]
207.6 ± 8.3 km (IRAS)[1]
Mass 1.63×1019 kg[3]
Mean density
3.46±0.79 g/cm³[3]
≈0.0580 m/s²
≈0.1098 km/s
0.2935 d[4]
(7.045 h)[1]
Albedo 0.083[1][5]
Temperature ~174 K
Spectral type
G-type asteroid[1]
9.71 to 12.46[6]

13 Egeria is a large main-belt G-type asteroid.[7] It was discovered by A. de Gasparis on November 2, 1850. Egeria was named by Urbain Le Verrier, whose computations led to the discovery of Neptune, after the mythological nymph Egeria of Aricia, Italy, the wife of Numa Pompilius, second king of Rome.[8]

OCCULT4 visualization of 13 Egeria occultation event of January 22, 2008

Egeria occulted a star on January 8, 1992. Its disc was determined to be quite circular (217×196 km). On January 22, 2008, it occulted another star, and this occultation was timed by several observers in New Mexico and Arizona, coordinated by the IOTA Asteroid Occultation Program.[2] The result showed that Egeria presented an approximately circular profile to Earth of 214.8×192 km, well in agreement with the 1992 occultation.[citation needed] It has also been studied by radar.[9]

In 1988 a search for satellites or dust orbiting this asteroid was performed using the UH88 telescope at the Mauna Kea Observatories, but the effort came up empty.[10] Spectral analysis of Egeria shows it to be unusually high in water content, 10.5–11.5% water by mass.[11] This makes Egeria a prominent candidate for future water-mining ventures.

See also[edit]


  1. ^ a b c d e f "JPL Small-Body Database Browser: 13 Egeria" (2008-11-04 last obs). Retrieved 2008-11-25. 
  2. ^ a b Timerson, Brad. "IOTA Asteroid Occultation Results for 2008". Retrieved 2010-01-19.  (Chords)
  3. ^ a b Jim Baer (2008). "Recent Asteroid Mass Determinations". Personal Website. Retrieved 2008-11-28. 
  4. ^ "Lightcurves and map data on numbered asteroids N° 1 to 52225". AstroSurf. Archived from the original on 2005-11-27. Retrieved 2008-11-03. 
  5. ^ "Asteroid Data Archive". Planetary Science Institute. Archived from the original on 2006-06-23. Retrieved 2008-11-03. 
  6. ^ apmag 9.71 (2061-Nov-06) to 12.46 (1990-Mar-12) JPL Horizons daily output for 1950 to 2099
  7. ^ Rivkin, A. S.; J. K. Davies; S. L. Ellison; L. A. Lebofsky. "High-resolution 2.5–3.5 M Observations of C-, B- and G-class asteroids." (PDF). Retrieved 2008-04-20. 
  8. ^ Schmadel, Lutz D. (2003). Dictionary of minor planet names 1 (5th ed.). Berlin Heidelberg New York: Springer-Verlag. p. 16. ISBN 3-540-00238-3. 
  9. ^ "Radar-Detected Asteroids and Comets". NASA/JPL Asteroid Radar Research. Retrieved 2011-10-30. 
  10. ^ 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. 
  11. ^ http://www.lpi.usra.edu/meetings/lpsc2002/pdf/1414.pdf

External links[edit]