Editing 9 Metis (section)

{{Short description|Main-belt asteroid}}
{{Distinguish|text=Jupiter's moon [[Metis (moon)|Metis]]}}
{{Use dmy dates|date=September 2019}}
{{Infobox planet
| minorplanet = yes
| background=#D6D6D6 
| name=9 Metis
| image= 9 Metis VLT (2021), deconvolved.pdf
| image_size= 
| caption=
| symbol=[[Image:Metis symbol (bold).svg|24px]] (historical)
| discoverer=[[Andrew Graham (astronomer)|A. Graham]]
| discovered=25 April 1848
| mpc_name=(9) Metis
| alt_names={{mp|1974 QU|2}}
| pronounced = {{IPAc-en|ˈ|m|iː|t|ᵻ|s}}<ref>Noah Webster (1884) ''A Practical Dictionary of the English Language''</ref>
| named_after = [[Metis (mythology)|Mētis]]
| adjectives = Metidian {{IPAc-en|m|ɛ|ˈ|t|ɪ|d|i|ə|n}}
| mp_category=[[Main belt]]
| orbit_ref =<ref name="jpldata">{{cite web
  |type=last observation: 2023-08-13
  |title=JPL Small-Body Database Browser: 9 Metis
  |url=http://ssd.jpl.nasa.gov/sbdb.cgi?sstr=9
  |access-date=2023-09-18}}</ref>
| epoch=13 September 2023<br/>([[Julian day|JD]]&nbsp;2453300.5)
| semimajor={{Convert|2.387|AU|e6km|abbr=unit}}
| perihelion={{Convert|2.093|AU|e6km|abbr=unit}}
| time_periastron=6 November 2023
| aphelion={{Convert|2.68|AU|e6km|abbr=unit|lk=on}}
| eccentricity=0.1231
| period=3.69 [[Julian year (astronomy)|yr]] (1346.74 d)
| inclination=5.577°
| asc_node=68.87°
| arg_peri=5.75°
| mean_anomaly=345.43°
| moid = {{Convert|1.1|AU|e6km|abbr=unit}}
| p_orbit_ref =<ref name=Metis-POE>{{cite web
  |title=AstDyS-2 Metis Synthetic Proper Orbital Elements
  |publisher=Department of Mathematics, University of Pisa, Italy
  |url=https://newton.spacedys.com/astdys/index.php?pc=1.1.6&n=9
  |access-date=1 October 2011}}</ref>
| p_semimajor = 2.3864354
| p_eccentricity = 0.1271833
| p_inclination = 4.6853629°
| p_mean_motion = 97.638314
| perihelion_rate = 38.754973
| node_rate = −41.998090
| mean_diameter={{val|173|2|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><br />190±? km (Dunham)<ref name="jpldata" />
| dimensions=(222 × 182 × 130) ± 12 km<ref name="Baer2011" />
| flattening = 0.39{{efn|1=Flattening derived from the maximum aspect ratio (c/a): <math>f=1-\frac{c}{a}</math>, where (c/a) = {{val|0.61|0.05}}.<ref name=VLT/>}}
|mass={{val|8.0|1.9|e=18|u=kg}}<ref name=VLT/><br />{{val|11.3|2.2|e=18|u=kg}}{{refn|group=lower-alpha|{{val|5.7|1.1|e=−12|u={{Solar mass}}}}}}<ref name="Baer2011">James Baer, Steven Chesley & Robert Matson (2011) "Astrometric masses of 26 asteroids and observations on asteroid porosity." ''The Astronomical Journal'', Volume 141, Number 5</ref>
|density={{val|2.94|0.70|u=g/cm3}}<ref name=VLT/><br />{{val|4.12|1.17|u=g/cm3}}<ref name="Baer2011"/>
| rotation=0.2116 d (5.079 h)<ref name="jpldata" />
| spectral_type=[[S-type asteroid|S]]<ref name="spiff">[http://spiff.rit.edu/richmond/parallax/phot/LCSUMPUB.TXT asteroid lightcurve data file (March 2001)]</ref>
| magnitude = 8.1<ref name="Pasachoff1983">{{cite book | author=Donald H. Menzel | author2=Jay M. Pasachoff | name-list-style=amp | date=1983 | title=A Field Guide to the Stars and Planets | edition=2nd | publisher=Houghton Mifflin | pages=[https://archive.org/details/fieldguidetostar00menz_0/page/391 391] | location=Boston, MA | isbn=0-395-34835-8 | url-access=registration | url=https://archive.org/details/fieldguidetostar00menz_0/page/391 }}</ref> to 11.83
| abs_magnitude=6.33<ref name="jpldata" />
| albedo=0.18<ref name=VLT/><br />0.118<ref name="jpldata" />
| angular_size = 0.23" <!-- Horizons 2012-Dec-24 --> to 0.071"
| single_temperature=''max:'' 282 K (+9&nbsp;°C)<ref name="Lim05">L. F. Lim et al., ''Thermal infrared (8–13 μm) spectra of 29 asteroids: the Cornell Mid-Infrared Asteroid Spectroscopy (MIDAS) Survey'', Icarus Vol. 173, p. 385 (2005).</ref>
}}

'''9 Metis''' is one of the larger [[main-belt]] [[asteroid]]s. It is composed of [[silicate]]s and [[metal]]lic [[nickel]]-[[iron]], and may be the core remnant of a large asteroid that was destroyed by an ancient collision.<ref name="Kelley00">{{cite journal
  |last=Kelley |first=Michael S
  |author2=Michael J. Gaffey
  |title=9 Metis and 113 Amalthea: A Genetic Asteroid Pair
  |journal=Icarus
  |volume=144 |issue=1 |pages=27–38 |date=2000
  |doi=10.1006/icar.1999.6266 |bibcode=2000Icar..144...27K}}</ref> Metis is estimated to contain just under half a percent of the total mass of the asteroid belt.<ref name="Baer">
{{cite web
  |date=2010
  |title=Recent Asteroid Mass Determinations
  |publisher=Personal Website
  |author=Jim Baer
  |url=http://home.earthlink.net/~jimbaer1/astmass.txt
  |access-date=13 February 2011
  |archive-url=https://web.archive.org/web/20130702212735/http://home.earthlink.net/~jimbaer1/astmass.txt
  |archive-date=2 July 2013
  |url-status=dead
  }}
</ref>