Английская Википедия:121 Hermione
Hermione (minor planet designation: 121 Hermione) is a very large binary asteroid discovered in 1872. It orbits in the Cybele group in the far outer asteroid belt.[1] As an asteroid of the dark C spectral type, it is probably composed of carbonaceous materials. In 2002, a small moon was found to be orbiting Hermione.[1]
Discovery
Hermione was discovered by J. C. Watson on 12 May 1872 from Ann Arbor, Michigan, in the United States,[1] and named after Hermione, daughter of Menelaus and Helen in Greek mythology.[2]
Physical properties
The asteroid has a bi-lobed shape, as evidenced by adaptive optics images, the first of which were taken in December 2003 with the Keck telescope.[3] Of several proposed shape models that agreed with the images, a "snowman"-like shape was found to best fit the observed precession rate of Hermione's satellite.[4] In this "snowman" model, the asteroid's shape can be approximated by two partially overlapping spheres of radii 80 and 60 km, whose centers are separated by a distance of 115 km. A simple ellipsoid shape was ruled out.
Observation of the satellite's orbit has made possible an accurate determination of Hermione's mass.[4] For the best-fit "snowman" model, the density is found to be 1.8 ± 0.2 g/cm3, giving a porosity on the order of 20%, and possibly indicating that the main components are fractured solid bodies, rather than the asteroid being a rubble pile.
Occultations by Hermione have been successfully observed three times so far, the last time in February 2004.
Moon
A satellite of Hermione was discovered in 2002 with the Keck II telescope.[1] It is about 8 miles (13 km) in diameter.[1] The satellite is provisionally designated S/2002 (121) 1. It has not yet been officially named, but "LaFayette" has been proposed by a group of astronomers in reference to the frigate used in secret by the Marquis de Lafayette to reach America to help the insurgents.[5][3]
References
External links
- 121 Hermione and S/2002 (121) 1, orbit data website maintained by F. Marchis. Includes adaptive optics images, orbit diagrams, and shape models.
- (121) Hermione, datasheet, johnstonsarchive.net
- Asteroids with Satellites, Robert Johnston, johnstonsarchive.net
- Tally of Asteroids Harboring Moons Grows Beyond 30 (Space.com, 3 October 2002)
- Шаблон:AstDys
- Шаблон:JPL small body
Шаблон:Use dmy dates Шаблон:Minor planets navigator Шаблон:Small Solar System bodies
- ↑ 1,0 1,1 1,2 1,3 1,4 Шаблон:Cite book
- ↑ Ошибка цитирования Неверный тег
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- Английская Википедия
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- Cybele asteroids
- Discoveries by James Craig Watson
- Named minor planets
- Binary asteroids
- Objects observed by stellar occultation
- C-type asteroids (Tholen)
- Ch-type asteroids (SMASS)
- Astronomical objects discovered in 1872
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