9 Metis

For the moon of Jupiter, see Metis (moon).

9 Metis is one of the biggest main belt asteroids. It is made of silicates and metallic nickel-iron, and may be the core remnant of a big asteroid that was destroyed by an ancient collision.M. S. Kelley and M. J. Gaffey, 9 Metis and 113 Amalthea: A Genetic Asteroid Pair, Icarus Vol. 144, p. 27 (2000).

 Discovery and naming 
Metis was found by Andrew Graham on April 25, 1848; it was his only asteroid discovery.Graham, A.; New Planet, Monthly Notices of the Royal Astronomical Society, Vol. 8, No. 6 (dated April 14, 1848!), p. 146 (signed April 29, 1848; the discovery was first announced on April 27) It is also the only asteroid to have been found as a result of observations from Ireland. Its name comes from the mythological Metis, a Titaness and Oceanid, daughter of Tethys and Oceanus.Graham, A.; Metis, Monthly Notices of the Royal Astronomical Society, Vol. 8, No. 7 (dated May 12, 1848), pp. 147 – 150) The name Thetis was also considered and rejected (it would later devolve to 17 Thetis).

 Characteristics 
Metis' direction of rotation is unknown at present.

Hubble space telescope images and lightcurve analyses are in agreement that Metis has a non-spherical stretched shape with one pointed and one broad end. Radar observations suggest the presence of a significant flat area,D. L. Mitchell et al., Radar Observations of Asteroids 7 Iris, 9 Metis, 12 Victoria, 216 Kleopatra, and 654 Zelinda, Icarus Vol. 118, p. 105 (1995). in agreement with the shape model from lightcurves.

What the surface is made of has been estimated as 30-40% metal-bearing olivine and 60-70% Ni-Fe metal.

Light curve data on Metis led to an assumption that it could have a moon. However, subsequent observations failed to confirm this.research at IMCCE  (in French)"other" reports of asteroid companions Later searches with the Hubble Space Telescope in 1993 found no moons.

 Occultations 
Metis has been seen to occult stars no less than 5 times.W. M. Kissling et al., The diameter of (9) Metis from the Occultation of SAO 190531, Proceedings of the Astronomical Society of Australia Vol 9, p. 150 (1991).

 References 

 Other websites 
 shape model deduced from lightcurve 
 "Notice of discovery of Metis", MNRAS 8 (1848) 146
 Irish Astronomical History: Markree Castle Observatory and The Discovery of the Asteroid Metis 
  — Horizons can be used to obtain a current ephemeris.

Category:Asteroids