13 Egeria

13 Egeria
Discovery
Discovered by	Annibale de Gasparis
Discovery site	Naples Obs.
Discovery date	2 November 1850
Designations
MPC designation	(13) Egeria
Pronunciation	/ɪˈdʒɪəriə/
Named after	Egeria
Minor planet category	Main belt
Adjectives	Egerian
Symbol	(historical)
Orbital characteristics
	Epoch 13 January 2016 (JD 2457400.5)
	Uncertainty parameter 0
Observation arc	60342 days (165.21 yr)
Aphelion	2.7927 AU (417.78 Gm)
Perihelion	2.36115 AU (353.223 Gm)
Semi-major axis	2.57690 AU (385.499 Gm)
Eccentricity	0.083726
Orbital period (sidereal)	4.14 yr (1510.9 d)
Average orbital speed	18.56 km/s
Mean anomaly	261.863°
Mean motion	0° 14m 17.736s / day
Inclination	16.539°
Longitude of ascending node	43.239°
Argument of perihelion	80.294°
Earth MOID	1.43999 AU (215.419 Gm)
Jupiter MOID	2.35966 AU (353.000 Gm)
TJupiter	3.364
Physical characteristics
Dimensions	214.8 km × 192 km
Mean diameter	202±3 km; 207.6 ± 8.3 km (IRAS)
Flattening	0.24
Mass	(9.2±2.1)×1018 kg; (15.9±4.4)×1018 kg
Mean density	2.13±0.49 g/cm3; 3.4±1.0 g/cm3
Equatorial surface gravity	≈0.0580 m/s2
Equatorial escape velocity	≈0.1098 km/s
Synodic rotation period	0.2935 d; (7.045 h)
Geometric albedo	0.087; 0.049 ± 0.028
Temperature	~174 K
Spectral type	G-type asteroid
Apparent magnitude	9.71 to 12.46
Absolute magnitude (H)	6.92

13 Egeria is a large main-belt G-type asteroid.^[9] It was discovered by Annibale 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.^[10]

The historical symbol for Egeria was a buckler. It is in the pipeline for Unicode 17.0 as U+1CEC6 𜻆 ().^[11]^[12]

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.^[3] 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.^[13]

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.^[14] Spectral analysis of Egeria shows it to be unusually high in water content, 10.5–11.5% water by mass.^[15] This makes Egeria a prominent candidate for future water-mining ventures.

Notes

^ Flattening derived from the maximum aspect ratio (c/a): $f=1-{\frac {c}{a}}$ , where (c/a) = 0.76±0.06.^[4]
^ (8.0±2.2)×10⁻¹² M_☉

References

^ Noah Webster (1884) A Practical Dictionary of the English Language
^ ^a ^b ^c ^d ^e ^f "JPL Small-Body Database Browser: 13 Egeria" (2008-11-04 last obs). Retrieved 8 April 2016.
^ ^a ^b Timerson, Brad. "IOTA Asteroid Occultation Results for 2008". Archived from the original on 16 April 2014. Retrieved 19 January 2010.
^ ^a ^b ^c ^d ^e P. Vernazza et al. (2021) VLT/SPHERE imaging survey of the largest main-belt asteroids: Final results and synthesis. Astronomy & Astrophysics 54, A56
^ ^a ^b James Baer, Steven Chesley & Robert Matson (2011) "Astrometric masses of 26 asteroids and observations on asteroid porosity." The Astronomical Journal, Volume 141, Number 5
^ "Lightcurves and map data on numbered asteroids N° 1 to 52225". AstroSurf. Archived from the original on 27 November 2005. Retrieved 3 November 2008.
^ "Asteroid Data Archive". Planetary Science Institute. Archived from the original on 23 May 2006. Retrieved 3 November 2008.
^ apmag 9.71 (2061-Nov-06) to 12.46 (1990-Mar-12) JPL Horizons daily output for 1950 to 2099
^ Rivkin, A. S.; J. K. Davies; S. L. Ellison; L. A. Lebofsky. "High-resolution 2.5–3.5 𝜇M Observations of C-, B- and G-class asteroids" (PDF). Retrieved 20 April 2008.
^ Schmadel, Lutz D. (2003). Dictionary of minor planet names. Vol. 1 (5th ed.). Berlin Heidelberg New York: Springer-Verlag. p. 16. ISBN 3-540-00238-3.
^ Bala, Gavin Jared; Miller, Kirk (18 September 2023). "Unicode request for historical asteroid symbols" (PDF). unicode.org. Unicode. Retrieved 26 September 2023.
^ Unicode. "Proposed New Characters: The Pipeline". unicode.org. The Unicode Consortium. Retrieved 6 November 2023.
^ "Radar-Detected Asteroids and Comets". NASA/JPL Asteroid Radar Research. Retrieved 30 October 2011.
^ 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, vol. 19, pp. 405–406, Bibcode:1988LPI....19..405G.
^ Rivkin, A. S.; Davies, J. K. (2002). "Calculated water concentrations on C-class asteroids" (PDF). Lunar and Planetary Science (XXXIII).

External links

"Elements and Ephemeris for (13) Egeria". Minor Planet Center. Archived from the original on 4 March 2016. Retrieved 26 May 2011. (displays Elong from Sun and V mag for 2011)
13 Egeria at AstDyS-2, Asteroids—Dynamic Site
- Ephemeris · Observation prediction · Orbital info · Proper elements · Observational info
13 Egeria at the JPL Small-Body Database
- Close approach · Discovery · Ephemeris · Orbit viewer · Orbit parameters · Physical parameters

[5] Flattening derived from the maximum aspect ratio (c/a): $f=1-{\frac {c}{a}}$ , where (c/a) = 0.76±0.06.^[4]

[6] (8.0±2.2)×10⁻¹² M_☉

[1] Noah Webster (1884) A Practical Dictionary of the English Language

[jpldata-2] ^ ^a ^b ^c ^d ^e ^f "JPL Small-Body Database Browser: 13 Egeria" (2008-11-04 last obs). Retrieved 8 April 2016.

[2008a-3] Timerson, Brad. "IOTA Asteroid Occultation Results for 2008". Archived from the original on 16 April 2014. Retrieved 19 January 2010.

[VLT-4] P. Vernazza et al. (2021) VLT/SPHERE imaging survey of the largest main-belt asteroids: Final results and synthesis. Astronomy & Astrophysics 54, A56

[Baer2011-7] James Baer, Steven Chesley & Robert Matson (2011) "Astrometric masses of 26 asteroids and observations on asteroid porosity." The Astronomical Journal, Volume 141, Number 5

[8] "Lightcurves and map data on numbered asteroids N° 1 to 52225". AstroSurf. Archived from the original on 27 November 2005. Retrieved 3 November 2008.

[9] "Asteroid Data Archive". Planetary Science Institute. Archived from the original on 23 May 2006. Retrieved 3 November 2008.

[10] 9.71 (2061-Nov-06) to 12.46 (1990-Mar-12) JPL Horizons daily output for 1950 to 2099

[11] Rivkin, A. S.; J. K. Davies; S. L. Ellison; L. A. Lebofsky. "High-resolution 2.5–3.5 𝜇M Observations of C-, B- and G-class asteroids" (PDF). Retrieved 20 April 2008.

[12] Schmadel, Lutz D. (2003). Dictionary of minor planet names. Vol. 1 (5th ed.). Berlin Heidelberg New York: Springer-Verlag. p. 16. ISBN 3-540-00238-3.

[astunicode-13] Bala, Gavin Jared; Miller, Kirk (18 September 2023). "Unicode request for historical asteroid symbols" (PDF). unicode.org. Unicode. Retrieved 26 September 2023.

[pipeline-14] Unicode. "Proposed New Characters: The Pipeline". unicode.org. The Unicode Consortium. Retrieved 6 November 2023.

[detected-15] "Radar-Detected Asteroids and Comets". NASA/JPL Asteroid Radar Research. Retrieved 30 October 2011.

[Gradie1988-16] 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, vol. 19, pp. 405–406, Bibcode:1988LPI....19..405G.

[17] Rivkin, A. S.; Davies, J. K. (2002). "Calculated water concentrations on C-class asteroids" (PDF). Lunar and Planetary Science (XXXIII).

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v t e Large asteroids (mean diameter greater than 200 km)
Mean diameter 900–1000 km	Ceres (a dwarf planet)
Mean diameter 500–600 km	Vesta Pallas
Mean diameter 300–500 km	Hygiea Interamnia Europa
Mean diameter 200–300 km	Davida Euphrosyne Patientia Sylvia Juno Cybele Eunomia Thisbe Psyche Hektor Bamberga Doris Ursula Camilla Aurora Daphne Egeria Eugenia Fortuna Iris

See also

Notes

References

External links