51 Nemausa

51 Nemausa
VLT-SPHERE image of Nemausa
Discovery
Discovered byJ. Laurent
Discovery siteNîmes
Discovery date22 January 1858
Designations
Pronunciation/nɛˈmɔːsə/
Named after
Nemausus
Main belt
AdjectivesNemausian /nɛˈmɔːsiən/
Orbital characteristics
Epoch 31 December 2006 (JD 2454100.5)
Aphelion2.523 AU (377.381 million km)
Perihelion2.208 AU (330.360 million km)
2.365 AU (353.871 million km)
Eccentricity0.066
3.64 a (1328.853 d)
316.668°
Inclination9.972°
176.168°
2.820°
Physical characteristics
Dimensions170×136 km
150±3 km
Flattening0.23
Mass(3.06±0.16)×1018 kg
Mean density
1.73±0.14 g/cm3
7.783 h
168°
−60°
0.09 (calculated)
0.093
G
7.74

51 Nemausa is a large main-belt asteroid that was discovered on 22 January 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.

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. It may have a water content of about 14%.

The first stellar occultation was observed on 17 August 1979, from the Gissar and Alma-Ata observatories produced two chords which were used to estimate a diameter of 150 km for the asteroid.

This is close to the present-day estimate of 147.9 km. Since then 51 Nemausa has been observed 20 times 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. Nemausa has been studied by radar.

See also

Notes

  1. ↑ Flattening derived from the maximum aspect ratio (c/a): , where (c/a) = 0.77±0.04.
  2. ↑ Calculated from its standard gravitational parameter GM = 0.204±0.011 km3/s2.

References

  1. ↑ John Craig (1869) The Universal English Dictionary
  2. ↑ "Diameters". Astronomical Applications Department of the U.S. Naval Observatory. Archived from the original on 27 September 2011. Retrieved 23 May 2008.
  3. 1 2 3 P. Vernazza et al. (2021) VLT/SPHERE imaging survey of the largest main-belt asteroids: Final results and synthesis. Astronomy & Astrophysics 54, A56
  4. 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.
  5. ↑ "51 Nemausa (A858 BA)". JPL Small-Body Database. Jet Propulsion Laboratory. SPK-ID: 20000051. Retrieved 18 December 2024.
  6. 1 2 Wang, Shuang; Yang, Yuangui; Yuan, Huiyu; Yu, Ligang (October 2025). "CCD photometric studies of two Primitive C-type main-belt asteroids: (51) Nemausa and (52) Europa". New Astronomy. 119 102391. doi:10.1016/j.newast.2025.102391.
  7. ↑ Asteroid Data Sets Archived 17 December 2009 at the Wayback Machine
  8. ↑ Schmadel, Lutz D. (2003). Dictionary of Minor Planet Names. Springer Science & Business Media. p. 20. ISBN 978-3-540-00238-3.
  9. ↑ 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, p. 1285, Bibcode:2009LPI....40.1285R.
  10. ↑ A. S. Rivkin (2002). "CALCULATED WATER CONCENTRATIONS ON C CLASS ASTEROIDS" (PDF). Lunar and Planetary Institute. Retrieved 22 May 2008.
  11. ↑ Kristensen, L.K. (June 1981). "The Size of 51 NEMAUSA". Astronomy and Astrophysics Supplement Series. 44: 375. Bibcode:1981A&AS...44..375K. ISSN 0365-0138. Archived from the original on 9 August 2025. Retrieved 12 October 2026.
  12. ↑ "Asteroid Data Sets". sbn.psi.edu. Retrieved 27 May 2018.
  13. ↑ Other reports of asteroid/TNO companions
  14. ↑ "Radar-Detected Asteroids and Comets". NASA/JPL Asteroid Radar Research. Retrieved 30 October 2011.