354 Eleonora

354 Eleonora
	VLT-SPHERE image of Eleonora
Discovery
Discovered by	Auguste Charlois
Discovery date	17 January 1893
Designations
Pronunciation	/ɛliəˈnɔːrə/
Alternative designations	1893 A
Minor planet category	Main belt
Adjectives	Eleonorian
Orbital characteristics
	Epoch 31 July 2016 (JD 2457600.5)
	Uncertainty parameter 0
Observation arc	123.16 yr (44983 d)
Aphelion	3.1188 AU (466.57 Gm)
Perihelion	2.47676 AU (370.518 Gm)
Semi-major axis	2.79777 AU (418.540 Gm)
Eccentricity	0.11474
Orbital period (sidereal)	4.68 yr (1709.3 d)
Mean anomaly	123.762°
Mean motion	0° 12m 38.196s / day
Inclination	18.403°
Longitude of ascending node	140.37°
Argument of perihelion	5.5215°
Physical characteristics
Dimensions	0.25
Mean diameter	165±3 km; 154.3±5.6 km (composite estimate); 148.970±0.425 km
Mass	(6.61±0.49)×1018 kg
Mean density	2.81±0.26 g/cm3
Synodic rotation period	4.277 h (0.1782 d)
Geometric albedo	0.172; 0.201±0.052
Spectral type	S
Absolute magnitude (H)	6.15

354 Eleonora is a large, stony main-belt asteroid that was discovered by the French astronomer Auguste Charlois on January 17, 1893, in Nice. This asteroid is orbiting the Sun at a distance of 2.80 AU with a moderate eccentricity (ovalness) of 0.11 and an orbital period of 4.68 years. The orbital plane is inclined at an angle of 18.4° to the plane of the ecliptic.

Photometric observations of this asteroid gave a light curve with a period of 13.623 hours. The data was used to construct a model for the asteroid, revealing it to be a regular-shaped object, spinning about a pole with ecliptic coordinates (β, λ) = (+20°, 356°), although this is with an accuracy of only ±10°. The ratio of the major to minor axes lengths is roughly equal to 1.2.

It is classified as a stony S-type asteroid and has an estimated size of 154.34 km. The spectrum of 354 Eleonora reveals the strong presence of the mineral olivine, a relative rarity in the asteroid belt. The surface spectrum is consistent with fine-grained material consisting of 60–70% olivine and 7–8% nickel.

During favorable oppositions, such as in 1968 and 2010, Eleonora can reach an apparent magnitude of +9.31.

Notes

↑ Flattening derived from the maximum aspect ratio (c/a): $f=1-{\frac {c}{a}}$ , where (c/a) = 0.75±0.08.
↑ Calculated from its standard gravitational parameter GM = 0.441±0.033 km³/s².
↑ Assuming a diameter of 165 ± 3 km.

References

↑ "Eleonora". Oxford English Dictionary (online ed.). Oxford University Press. (Subscription or participating institution membership required.)
1 2 3 4 5 6 Yeomans, Donald K., "354 Eleonora", JPL Small-Body Database Browser, NASA Jet Propulsion Laboratory, retrieved 11 May 2016.
1 2 3 Vernazza, P.; et al. (2021), "VLT/SPHERE imaging survey of the largest main-belt asteroids: Final results and synthesis", Astronomy & Astrophysics, 54, Bibcode:2021A&A...654A..56V, doi:10.1051/0004-6361/202141781, hdl:10261/263281, A56.
1 2 Carry, B. (December 2012), "Density of asteroids", Planetary and Space Science, 73 (1): 98–118, arXiv:1203.4336, Bibcode:2012P&SS...73...98C, doi:10.1016/j.pss.2012.03.009, S2CID 119226456. See Table 1.
1 2 Fuentes-Muñoz, Oscar; Farnocchia, Davide; Giorgini, Jon D.; Park, Ryan S. (1 December 2025). "Asteroid Mass Estimation by Mutual Perturbations During Close Encounters After Gaia Focused Product Release". The Astronomical Journal. 170 (6): 353. Bibcode:2025AJ....170..353F. doi:10.3847/1538-3881/ae0cc9. ISSN 0004-6256. S2CID 283347135.
↑ "Numbered Minor Planets 1–5000", Discovery Circumstances, IAU Minor Planet center, retrieved 7 April 2013.
↑ Kaasalainen, M.; et al. (October 2002), "Models of Twenty Asteroids from Photometric Data", Icarus, 159 (2): 369–395, Bibcode:2002Icar..159..369K, doi:10.1006/icar.2002.6907.
↑ Burbine, T. H.; et al. (July 2000), "The Nature of Olivine Asteroids", Meteoritics & Planetary Science, vol. 35, pp. A35, Bibcode:2000M&PSA..35R..35B, doi:10.1111/j.1945-5100.2000.tb01796.x.
↑ Gaffey, Michael J.; Reddy, Vishnu; Fieber-Beyer, Sherry; Cloutis, Edward (April 2015), "Asteroid (354) Eleonora: Plucking an odd duck", Icarus, 250: 623–638, Bibcode:2015Icar..250..623G, doi:10.1016/j.icarus.2014.12.036.

External links

354 Eleonora at AstDyS-2, Asteroids—Dynamic Site
- Ephemeris · Observation prediction · Orbital info · Proper elements · Observational info
354 Eleonora at the JPL Small-Body Database
- Close approach · Discovery · Ephemeris · Orbit viewer · Orbit parameters · Physical parameters

[4] Flattening derived from the maximum aspect ratio (c/a): $f=1-{\frac {c}{a}}$ , where (c/a) = 0.75±0.08.

[7] Calculated from its standard gravitational parameter GM = 0.441±0.033 km³/s².

[8] Assuming a diameter of 165 ± 3 km.

[1] "Eleonora". Oxford English Dictionary (online ed.). Oxford University Press. (Subscription or participating institution membership required.)

[JPL-2] 1 2 3 4 5 6 Yeomans, Donald K., "354 Eleonora", JPL Small-Body Database Browser, NASA Jet Propulsion Laboratory, retrieved 11 May 2016.

[VLT-3] 1 2 3 Vernazza, P.; et al. (2021), "VLT/SPHERE imaging survey of the largest main-belt asteroids: Final results and synthesis", Astronomy & Astrophysics, 54, Bibcode:2021A&A...654A..56V, doi:10.1051/0004-6361/202141781, hdl:10261/263281, A56.

[Carry2012-5] 1 2 Carry, B. (December 2012), "Density of asteroids", Planetary and Space Science, 73 (1): 98–118, arXiv:1203.4336, Bibcode:2012P&SS...73...98C, doi:10.1016/j.pss.2012.03.009, S2CID 119226456. See Table 1.

[Fuentes-Muñoz2025-6] 1 2 Fuentes-Muñoz, Oscar; Farnocchia, Davide; Giorgini, Jon D.; Park, Ryan S. (1 December 2025). "Asteroid Mass Estimation by Mutual Perturbations During Close Encounters After Gaia Focused Product Release". The Astronomical Journal. 170 (6): 353. Bibcode:2025AJ....170..353F. doi:10.3847/1538-3881/ae0cc9. ISSN 0004-6256. S2CID 283347135.

[IAU_MPC-9] "Numbered Minor Planets 1–5000", Discovery Circumstances, IAU Minor Planet center, retrieved 7 April 2013.

[Kaasalainen2002-10] Kaasalainen, M.; et al. (October 2002), "Models of Twenty Asteroids from Photometric Data", Icarus, 159 (2): 369–395, Bibcode:2002Icar..159..369K, doi:10.1006/icar.2002.6907.

[Burbine2000-11] Burbine, T. H.; et al. (July 2000), "The Nature of Olivine Asteroids", Meteoritics & Planetary Science, vol. 35, pp. A35, Bibcode:2000M&PSA..35R..35B, doi:10.1111/j.1945-5100.2000.tb01796.x.

[Gaffey_et_al_2015-12] Gaffey, Michael J.; Reddy, Vishnu; Fieber-Beyer, Sherry; Cloutis, Edward (April 2015), "Asteroid (354) Eleonora: Plucking an odd duck", Icarus, 250: 623–638, Bibcode:2015Icar..250..623G, doi:10.1016/j.icarus.2014.12.036.