9 Metis

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Template:Minor Planet 9 Metis (mee'-tis) is one of the largest Main belt asteroids. It is composed of silicates and metallic nickel-iron, and may be the core remnant of a large asteroid that was destroyed by an ancient collision ^[12].

1 Discovery and naming
2 Characteristics
3 Family relationships
4 Occultations
5 References
6 Aspects
7 External links

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Discovery and naming

Image:Moon and Asteroids 1 to 10 at 10 km per px.png Metis was discovered by Andrew Graham on April 25, 1848; his only asteroid discovery. It is also the only asteroid to have been discovered as a result of observations from Ireland. Its name comes from the mythological Metis, a Titaness, daughter of Tethys and Oceanus (and thus an Oceanid), who was the first wife of Zeus and the mother of Athena. Zeus devoured her lest she bear a child more powerful than he.

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Characteristics

Metis's direction of rotation is unknown at present, due to ambiguous data. Lightcurve analysis indicates that Metis's pole points towards either ecliptic coordinates (β, λ) = (23°, 181°) or (9°, 359°) with a 10° uncertainty ^[1]. This gives an axial tilt of 72° or 76°, respectively.

Hubble space telescope images^[1][9] and lightcurve analyses^[1] are in agreement that Metis has an irregular elongated shape with one pointed and one broad end (images and shape models here). Radar observations suggest the presence of a significant flat area^[13], in agreement with the shape model from lightcurves.

The surface composition has been estimated as 30-40% metal-bearing olivine and 60-70% Ni-Fe metal.^[12].

Light curve data on Metis led to an assumption that it could have a satellite. However, subsequent observations failed to confirm this. ^{[2] [3]} Later searches with the Hubble Space Telescope in 1993 found no satellites. ^[5]

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Family relationships

Metis was once considered to be a member of an asteroid family (the Metis family)^[11], but more recent searches for prominent families did not recognize any such group, nor is a clump evident in the vicinity of Metis by visual inspection of proper orbital element diagrams.

However, a spectroscopic analysis found strong spectral similarities between Metis and the nearby astroid 113 Amalthea, and it is suggested that these asteroids may be remnants of a very old (> ~ 1 Gyr) dynamical family whose smaller members have been pulverised by collisions or perturbed away from the vicinity. The putative parent body is estimated to have been 300 to 600 km in diameter (Vesta - sized), differentiated, and Metis would be the relatively intact core remnant, while Amalthea a fragment of the mantle. ^[12]

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Occultations

Metis has been observed occulting a star no less than 5 times. See e.g. [4].

Metis is also the name of a satellite of Jupiter.

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References

J. Torppa et al Shapes and rotational properties of thirty asteroids from photometric data, Icarus Vol. 164, p. 346 (2003).
PDS lightcurve data
asteroid lightcurve data file (March 2001)
MSX Infrared minor planet survey (at PDS)
Hubble Space Telescope observations
research at IMCCE (in French)
"other" reports of asteroid companions
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).
A. D. Storrs et al A closer look at main belt asteroids 1: WF/PC images, Icarus Vol. 173, p. 409 (2005).
G. A. Krasinsky et al Hidden Mass in the Asteroid Belt, Icarus, Vol. 158, p. 98 (2002).
J. G. Williams Asteroid Families - An Initial Search, Icarus Vol. 96, p. 251 (1992).
M.S. Kelley and M. J. Gaffey 9 Metis and 113 Amalthea: A Genetic Asteroid Pair, Icarus Vol. 144, p. 27 (2000).
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).
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).

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Aspects

Stationary, retrograde	Opposition	Distance to earth (AU)	Maximum brightness	Stationary, prograde	Conjunction to Sun
January 19, 2006	March 3, 2006	1.35200	9.1 mag	April 20, 2006	June 7, 2005
May 4, 2007	June 23, 2007	1.64582	9.7 mag	August 13, 2007	November 5, 2006
September 24, 2008	November 5, 2008	1.13923	8.4 mag	December 19, 2008	February 15, 2008
February 23, 2010	April 11, 2010	1.53609	9.5 mag	June 3, 2010	August 7, 2009
June 11, 2011	July 28, 2011	1.53974	9.6 mag	September 16, 2011	December 6, 2010
November 23, 2012	January 2, 2013	1.13905	8.5 mag	February 12, 2013	March 30, 2012
March 26, 2014	May 15, 2014	1.64402	9.6 mag	July 7, 2014	September 23, 2013
July 25, 2015	September 6, 2015	1.35478	9.2 mag	October 25, 2015	January 5, 2015
January 11, 2017	February 22, 2017	1.31456	9.0 mag	April 10, 2017	May 27, 2016
April 28, 2018	June 17, 2018	1.65468	9.7 mag	August 7, 2018	October 30, 2017
September 14, 2019	October 27, 2019	1.16286	8.6 mag	December 10, 2019	February 8, 2019