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51 Nemausa
Discovery
Discovered by	J. Laurent
Discovery site	Nîmes
Discovery date	January 22, 1858
Designations
MPC designation	(51) Nemausa
Pronunciation	/nɛˈmɔːsə/
Named after	Nemausus
Minor planet category	Main belt
Adjectives	Nemausian /nɛˈmɔːsiən/
Orbital characteristics
	Epoch December 31, 2006 (JD 2454100.5)
Aphelion	2.523 AU (377.381 Gm)
Perihelion	2.208 AU (330.360 Gm)
Semi-major axis	2.365 AU (353.871 Gm)
Eccentricity	0.066
Orbital period (sidereal)	3.64 a (1328.853 d)
Mean anomaly	316.668°
Inclination	9.972°
Longitude of ascending node	176.168°
Argument of perihelion	2.820°
Physical characteristics
Dimensions	c/a = 0.77±0.04; 170×136 km
Mean diameter	150±3 km
Mass	(3.9±1.6)×1018 kg ; (2.48±0.86)×1018 kg
Mean density	2.2±0.9 g/cm3; 1.43±0.50 g/cm3
Geometric albedo	0.09 (calculated); 0.093
Spectral type	G
Absolute magnitude (H)	7.35

51 Nemausa is a large main-belt asteroid that was discovered on January 22, 1858, by Joseph Jean Pierre Laurent. Laurent made the discovery from the private observatory of Benjamin Valz in Nîmes, France. The house, at 32 rue Nationale in Nîmes, has a plaque commemorating the discovery. With Laurent's permission, Valz named the asteroid after the Celtic god Nemausus, the patron god and namesake of Nîmes during Roman times.^[6]

Based upon its spectrum, this is listed as a C-type asteroid in the Tholen classification taxonomy, and as a Cgh by Bus and Binzel (2002). This indicates a composition similar to carbonaceous chondrite meteorites. Absorption features in the spectrum indicate the presence of phyllosilicates.^[7] It may have a water content of about 14%.^[8]

The first stellar occultation was observed on August 17, 1979, from the Gissar and Alma-Ata observatories produced two chords which were used to estimate a diameter of 150 km for the asteroid.^[9] This is close to the present-day estimate of 147.9 km. Since then 51 Nemausa has been observed 20 times^[10] in stellar occultation.

Light curve inversion model DAMIT 1065 is a good match to a seven-chord occultation observed on 3 September 2016, from which an equivalent mean diameter of 146.4 km, and an equivalent Surface mean diameter of 150.3 km was obtained.

Lightcurve data suggests that it may have a small moon.^[11] Nemausa has been studied by radar.^[12]

Images related to 51 Nemausa

A light-curve Inversion model (DAMIT 1065) and a seven-chord occultation of 51 Nemausa
Chart dated 22 January 1858
Detail of handwritten legend at top ("J. Laurent")

References

^ John Craig (1869) The Universal English Dictionary
^ ^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
^ "Diameters". Astronomical Applications Department of the U.S. Naval Observatory. Archived from the original on 27 September 2011. Retrieved 23 May 2008.
^ ^a ^b Carry, B. (December 2012), "Density of asteroids", Planetary and Space Science, vol. 73, pp. 98–118, arXiv:1203.4336, Bibcode:2012P&SS...73...98C, doi:10.1016/j.pss.2012.03.009. See Table 1.
^ Asteroid Data Sets Archived 2009-12-17 at the Wayback Machine
^ Schmadel, Lutz D. (2003). Dictionary of Minor Planet Names. Springer Science & Business Media. p. 20. ISBN 978-3-540-00238-3.
^ Reynolds, C. M.; et al. (March 2009), "Compositional Study of 51 Nemausa: A Possible Carbonaceous Chondrite-like Asteroid", 40th Lunar and Planetary Science Conference, (Lunar and Planetary Science XL), held March 23–27, 2009 in The Woodlands, Texas, vol. 73, Bibcode:2009LPI....40.1285R.
^ A. S. Rivkin (2002). "CALCULATED WATER CONCENTRATIONS ON C CLASS ASTEROIDS" (PDF). Lunar and Planetary Institute. Retrieved 22 May 2008.
^
^ "Asteroid Data Sets". sbn.psi.edu. Retrieved 27 May 2018.
^ Other reports of asteroid/TNO companions
^ "Radar-Detected Asteroids and Comets". NASA/JPL Asteroid Radar Research. Retrieved 30 October 2011.