 | |
| Discovery | |
|---|---|
| Discovered by | J. Laurent |
| Discovery site | Nîmes |
| Discovery date | January 22, 1858 |
| Designations | |
| (51) Nemausa | |
| Pronunciation | /nɛˈmɔːsə/[1] |
Named after | Nemausus |
| Main belt | |
| Adjectives | Nemausian/nɛˈmɔːsiən/ |
| Orbital characteristics | |
| Epoch December 31, 2006 (JD 2454100.5) | |
| Aphelion | 2.523AU (377.381 Gm) |
| Perihelion | 2.208 AU (330.360 Gm) |
| 2.365 AU (353.871 Gm) | |
| Eccentricity | 0.066 |
| 3.64a (1328.853 d) | |
| 316.668° | |
| Inclination | 9.972° |
| 176.168° | |
| 2.820° | |
| Physical characteristics | |
| Dimensions | 170×136 km[2] |
| 150±3 km[3] | |
| Flattening | 0.23[a] |
| Mass | (3.9±1.6)×1018 kg[3] (2.48±0.86)×1018 kg[4] |
Meandensity | 2.2±0.9 g/cm3[3] 1.43±0.50 g/cm3[4] |
| 7.783 h[5] | |
| 0.09 (calculated)[3] 0.093[6] | |
| G | |
| 7.74[5] | |
51 Nemausa is a largemain-beltasteroid that was discovered on January 22, 1858, byJoseph Jean Pierre Laurent. Laurent made the discovery from the private observatory ofBenjamin Valz inNîmes,France. The house, at 32 rue Nationale in Nîmes, has a plaque commemorating the discovery. With Laurent's permission, Valz named the asteroid after theCeltic godNemausus, the patron god and namesake of Nîmes during Roman times.[7]
Based upon its spectrum, this is listed as aC-type asteroid in theTholen classification taxonomy, and as a Cgh by Bus and Binzel (2002). This indicates a composition similar tocarbonaceous chondrite meteorites.Absorption features in the spectrum indicate the presence ofphyllosilicates.[8] It may have a water content of about 14%.[9]
The firststellaroccultation 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.[10] This is close to the present-day estimate of 147.9 km. Since then 51 Nemausa has been observed 20 times[11] in stellar occultation.
Light curve inversion modelDAMIT1065 is a good match to a seven-chord occultation observed on 3 September 2016, from which an equivalentmean 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 smallmoon.[12] Nemausa has been studied byradar.[13]
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