|Discovered by||A. Graham|
|Discovery date||April 25, 1848|
|Alternative names||1974 QU2|
|Minor planet category||Main belt|
|Epoch July 14, 2004 (JD 2453200.5)|
|Aphelion||400.548 Gm (2.678 AU)|
|Perihelion||313.556 Gm (2.096 AU)|
|Semi-major axis||357.052 Gm (2.387 AU)|
|Orbital period||1346.815 d (3.69 a)|
|Average orbital speed||19.21 km/s|
|Longitude of ascending node||68.982°|
|Argument of perihelion||5.489°|
|Mean density||~2.7 g/cm³|
|Equatorial surface gravity||~0.070 m/s²|
|Escape velocity||~0.11 km/s|
|Rotation period||0.2116 d (5.078 h)|
max: 282 K (+9° C)
|Apparent magnitude||8.1 to 11.83|
|Absolute magnitude (H)||6.28|
|Angular diameter||0.23" to 0.071"|
Discovery and naming[change | edit source]
Metis was found by Andrew Graham on April 25, 1848; it was his only asteroid discovery. 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. The name Thetis was also considered and rejected (it would later devolve to 17 Thetis).
Characteristics[change | edit source]
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, in agreement with the shape model from lightcurves.
Light curve data on Metis led to an assumption that it could have a moon. However, subsequent observations failed to confirm this. Later searches with the Hubble Space Telescope in 1993 found no moons.
Occultations[change | edit source]
References[change | edit source]
- J. Torppa et al., Shapes and rotational properties of thirty asteroids from photometric data, Icarus Vol. 164, p. 346 (2003).
- 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).
- PDS lightcurve data
- MSX Infrared minor planet survey (at PDS)
- 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).
- asteroid lightcurve data file (March 2001)
- Donald H. Menzel and Jay M. Pasachoff (1983). A Field Guide to the Stars and Planets (2nd edition ed.). Boston, MA: Houghton Mifflin. pp. p. 391. ISBN 0-395-34835-8.
- M. S. Kelley and M. J. Gaffey, 9 Metis and 113 Amalthea: A Genetic Asteroid Pair, Icarus Vol. 144, p. 27 (2000).
- 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)
- Graham, A.; Metis, Monthly Notices of the Royal Astronomical Society, Vol. 8, No. 7 (dated May 12, 1848), pp. 147 – 150)
- Hubble Space Telescope observations
- 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).
- 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).
Other websites[change | edit source]
- 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
- Yeomans, Donald K.. "Horizons system". NASA JPL. http://ssd.jpl.nasa.gov/?horizons. Retrieved 2007-03-20. — Horizons can be used to obtain a current ephemeris.