{{Short description|Main-belt asteroid}} {{Use dmy dates|date=October 2019}} {{Infobox planet | minorplanet = yes | background = #D6D6D6 | name = 51 Nemausa | image = 51 Nemausa VLT (2021), deconvolved.pdf | image_size = | caption = | pronounced = {{IPAc-en|n|ɛ|ˈ|m|ɔː|s|ə}}<ref>John Craig (1869) ''The Universal English Dictionary''</ref> | adjective = Nemausian {{IPAc-en|n|ɛ|ˈ|m|ɔː|s|i|ə|n}} | discoverer = J. Laurent | discovered = January 22, 1858 | discovery_site = Nîmes | mpc_name = (51) Nemausa | alt_names = | named_after = Nemausus | mp_category = Main belt | epoch = December 31, 2006 (JD 2454100.5) | semimajor = 2.365 AU (353.871 million km) | perihelion = 2.208 AU (330.360 million km) | aphelion = 2.523 AU (377.381 million km) | eccentricity = 0.066 | period = 3.64 a (1328.853 d) | inclination = 9.972° | asc_node = 176.168° | arg_peri = 2.820° | mean_anomaly = 316.668° | dimensions = 170×136 km<ref name=diameters>{{cite web |title=Diameters |publisher=Astronomical Applications Department of the U.S. Naval Observatory |url=http://aa.usno.navy.mil/AsAtest/SecG/Diameters.txt |access-date=2008-05-23 |url-status=dead |archive-url=https://web.archive.org/web/20110927084045/http://aa.usno.navy.mil/AsAtest/SecG/Diameters.txt |archive-date=2011-09-27 }}</ref> | flattening = 0.23{{efn|1=Flattening derived from the maximum aspect ratio (c/a): <math>f=1-\frac{c}{a}</math>, where (c/a) = {{val|0.77|0.04}}.<ref name=VLT/>}} | mean_diameter = {{val|150|3|u=km}}<ref name=VLT>P. Vernazza et al. (2021) VLT/SPHERE imaging survey of the largest main-belt asteroids: Final results and synthesis. ''Astronomy & Astrophysics'' 54, A56</ref> | mass = {{val|3.9|1.6|e=18|u=kg}}<ref name=VLT/> <br />{{val|2.48|0.86|e=18|ul=kg}}<ref name="Carry2012"/> | density = {{val|2.2|0.9|u=g/cm3}}<ref name=VLT/><br />{{val|1.43|0.50|u=g/cm3}}<ref name="Carry2012"/> | rotation = 7.783 h<ref name=JPL>{{Cite sbdb|title=51 Nemausa (A858 BA)|id=20000051|access-date=2024-12-18}}</ref> | spectral_type = G | abs_magnitude = 7.74 | pole_ecliptic_lat = −60°<ref name=CCD>{{cite web|url=https://www.sciencedirect.com/science/article/abs/pii/S1384107625000405|title=CCD photometric studies of two Primitive C-type main-belt asteroids: (51) Nemausa and (52) Europa|author=Shuang Wang, Yuangui Yang, Huiyu Yuan, Ligang Yu|date=October 2025}}</ref> | pole_ecliptic_lon = 168°<ref name=CCD></ref> | albedo = 0.09 (calculated)<ref name=VLT/><br />0.093<ref>[http://www.psi.edu/pds/resource/albedo.html Asteroid Data Sets<!-- Bot generated title -->] {{webarchive|url=https://web.archive.org/web/20091217104722/http://www.psi.edu/pds/resource/albedo.html |date=2009-12-17 }}</ref> }}

'''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.<ref>{{cite book|last=Schmadel|first=Lutz D.|title=Dictionary of Minor Planet Names|url=https://books.google.com/books?id=KWrB1jPCa8AC&pg=PA20|year=2003|publisher=Springer Science & Business Media|isbn=978-3-540-00238-3|page=20}}</ref>

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.<ref name="Reynolds2009"/> It may have a water content of about 14%.<ref name=water2002/>

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&nbsp;km for the asteroid. <ref name="Kristensen19812"><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Astronomy+and+Astrophysics+Supplement&rft.atitle=The+Size+of+51+Nemausa&rft.volume=44&rft.pages=375-377&rft.date=1981-06&rft_id=info%3Abibcode%2F1981A%26AS...44..375K&rft.aulast=Kristensen&rft.aufirst=L.+K.&rfr_id=info%3Asid%2Fen.wikipedia.org%3A51+Nemausa" class="Z3988"><span style="display:none;">&nbsp;</span></span></ref> This is close to the present-day estimate of 147.9&nbsp;km. Since then 51 Nemausa has been observed 20 times<ref>{{Cite web|url=https://sbn.psi.edu/pds/resource/occ.html|title=Asteroid Data Sets|website=sbn.psi.edu|access-date=2018-05-27}}</ref> in stellar occultation.

Light curve inversion model [http://astro.troja.mff.cuni.cz/projects/asteroids3D/web.php DAMIT] [http://astro.troja.mff.cuni.cz/projects/asteroids3D/data/archive/1-1000/A642.M1065.shape.png 1065] is a good match to a seven-chord occultation observed on 3 September 2016, from which an equivalent mean diameter of 146.4&nbsp;km, and an equivalent Surface mean diameter of 150.3&nbsp;km was obtained.

Lightcurve data suggests that it may have a small moon.<ref>[http://www.johnstonsarchive.net/astro/asteroidmoonsq.html Other reports of asteroid/TNO companions]</ref> Nemausa has been studied by radar.<ref name="detected" />

{{Gallery |title=Images related to 51 Nemausa |align=center |style= |File:51Nemausa 20160903 (OccultationAndInversion).jpg |A light-curve Inversion model (DAMIT 1065) and a seven-chord occultation of 51 Nemausa |File:Observatoire de Marseille - Patrimoines 86209 676366.jpg |alt2=Hello world |Chart dated 22 January 1858 |File:Observatoire de Marseille - Patrimoines 86209 676366 detail.jpg |alt3=Goodbye world |Detail of handwritten legend at top ("J. Laurent") }}

== See also == *162 Laurentia

==Notes== {{notelist}}

==References== {{Reflist|refs=

<ref name="Carry2012">{{Citation | first1 = B. | last1 = Carry | title = Density of asteroids | work = Planetary and Space Science | volume = 73 | pages = 98–118 |date=December 2012 | doi = 10.1016/j.pss.2012.03.009 | bibcode = 2012P&SS...73...98C | postscript= . |arxiv = 1203.4336 }} See Table 1.</ref>

<ref name=water2002>{{cite web | year=2002 | title=CALCULATED WATER CONCENTRATIONS ON C CLASS ASTEROIDS | publisher=Lunar and Planetary Institute | author=A. S. Rivkin | url=http://www.lpi.usra.edu/meetings/lpsc2002/pdf/1414.pdf | format=PDF | access-date=2008-05-22 }}</ref>

<ref name="detected">{{cite web | title=Radar-Detected Asteroids and Comets | publisher=NASA/JPL Asteroid Radar Research | url=http://echo.jpl.nasa.gov/asteroids/ | access-date=2011-10-30 }}</ref>

<ref name="Reynolds2009">{{Citation | last1 = Reynolds | first1 = C. M. | last2 = Reddy | first2 = V. | last3 = Gaffey | first3 = M. J. | display-authors = 1 | title = Compositional Study of 51 Nemausa: A Possible Carbonaceous Chondrite-like Asteroid | work = 40th Lunar and Planetary Science Conference, (Lunar and Planetary Science XL), held March 23–27, 2009 in The Woodlands, Texas | volume = 73 |date=March 2009 | bibcode = 2009LPI....40.1285R | postscript= . }}</ref>

}} <!-- end of reflist -->

== External links == * {{AstDys|51}} * {{JPL small body}}

{{Minor planets navigator |50 Virginia |number=51 |52 Europa}} {{Small Solar System bodies}} {{Authority control}}

{{DEFAULTSORT:000051}} Category:Background asteroids Nemausa Nemausa Category:Objects observed by stellar occultation Category:CU-type asteroids (Tholen) Category:Ch-type asteroids (SMASS) 18580122