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].
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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.
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]
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]
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.
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).
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 |
External links
- "Notice of discovery of Metis", MNRAS 8 (1848) 146
- Irish Astronomical History: Markree Castle Observatory and The Discovery of the Asteroid Metis
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de:Metis (Asteroid) es:(9) Metis fr:(9) Métis it:9 Metis ja:メティス (小惑星) nn:9 Metis pl:9 Metis pt:9 Métis sk:9 Metis