Discovery [1] | |
---|---|
Discovered by | James Craig Watson |
Discovery date | 12 May 1872 |
Designations | |
(121) Hermione | |
Pronunciation | /hɜːrˈmaɪ.əniː/ [2] |
Named after | Hermione [3] (Greek mythology) |
A872 JA; 1970 VE | |
main-belt · Cybele | |
Adjectives | Hermionean /hɜːrmaɪ.əˈniːən/ |
Orbital characteristics [4] | |
Epoch 23 March 2018 (JD 2458200.5) | |
Uncertainty parameter 0 | |
Observation arc | 145.96 yr (53,312 d) |
Aphelion | 3.9067 AU |
Perihelion | 2.9889 AU |
3.4478 AU | |
Eccentricity | 0.1331 |
6.40 yr (2,338 d) | |
157.08° | |
0° 9m 14.4s / day | |
Inclination | 7.5975° |
73.127° | |
298.18° | |
Known satellites | S/2002 (121) 1 |
Physical characteristics | |
Dimensions | 268 × 186 × 183 km [5] (254 ± 4) × (125 ± 9) km [6] |
95 km [6] | |
Volume | (3.0±0.4)×106 km3 [7] |
Mass | (5.381±5%)×1018 kg [7] |
Mean density | 1.8 ± 0.2 g/cm3 [7] [lower-alpha 1] |
Equatorial surface gravity | 0.022 m/s2 [lower-alpha 2] |
Equatorial escape velocity | 0.075 km/s [lower-alpha 2] |
0.2313 d (5.551 h) [8] | |
73° | |
Pole ecliptic latitude | +10 ± 2° [7] |
Pole ecliptic longitude | 1.5 ± 2° |
0.0482 ± 0.002 [9] | |
C [10] | |
7.31 [9] | |
121 Hermione is a very large binary asteroid discovered in 1872. It orbits in the Cybele group in the far outer asteroid belt. [11] 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. [11]
Hermione was discovered by J. C. Watson on 12 May 1872 from Ann Arbor, Michigan, in the United States, [11] and named after Hermione, daughter of Menelaus and Helen in Greek mythology. [3]
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. [6] 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. [7] 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. [7] 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.
Discovery [12] | |
---|---|
Discovered by | W. J. Merline, P. M. Tamblyn, C. Dumas, L. M. Close, C. R. Chapman, F. Menard, W. M. Owen, and D. C. Slater |
Discovery date | 2002-09-28 |
Designations | |
LaFayette | |
main-belt · Cybele | |
Orbital characteristics [13] | |
768 ± 11 km | |
Eccentricity | 0.001 ± 0.001 |
2.582 ± 0.002 d | |
Inclination | 3 ± 2° (with respect to Hermione pole) |
Satellite of | 121 Hermione |
Physical characteristics | |
Dimensions | 12 ± 4 km [6] |
Mass | ~1.6×1015 kg [lower-alpha 3] |
13.0 [6] | |
A satellite of Hermione was discovered in 2002 with the Keck II telescope. [11] It is about 8 miles (13 km) in diameter. [11] 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. [14] [6]
624 Hektor is the largest Jupiter trojan and the namesake of the Hektor family, with a highly elongated shape equivalent in volume to a sphere of approximately 225 to 250 kilometers diameter. It was discovered on 10 February 1907, by astronomer August Kopff at Heidelberg Observatory in southwest Germany, and named after the Trojan prince Hector, from Greek mythology. It has one small 12-kilometer sized satellite, Skamandrios, discovered in 2006.
90 Antiope is a double asteroid in the outer asteroid belt. It was discovered on October 1, 1866, by Robert Luther. In 2000, it was found to consist of two almost-equally-sized bodies orbiting each other. At average diameters of about 88 km and 84 km, both components are among the 500 largest asteroids. Antiope is a member of the Themis family of asteroids that share similar orbital elements.
45 Eugenia is a large asteroid of the asteroid belt. It is famed as one of the first asteroids to be found to have a moon orbiting it. It was also the second triple asteroid to be discovered, after 87 Sylvia.
87 Sylvia is one of the largest asteroids. It is the parent body of the Sylvia family and member of Cybele group located beyond the main asteroid belt. Sylvia was the first asteroid known to possess more than one moon.
107 Camilla is one of the largest asteroids from the outermost edge of the asteroid belt, approximately 250 kilometers in diameter. It is a member of the Sylvia family and located within the Cybele group. It was discovered on 17 November 1868, by English astronomer Norman Pogson at Madras Observatory, India, and named after Camilla, Queen of the Volsci in Roman mythology. The X-type asteroid is a rare trinary asteroid with two minor-planet moons discovered in 2001 and 2016, respectively. It is elongated in shape and has a short rotation period of 4.8 hours.
130 Elektra is a large outer main-belt asteroid and quadruple system with three minor-planet moons. It was discovered on 17 February 1873, by astronomer Christian Peters at Litchfield Observatory, New York, and named after Electra, an avenger in Greek mythology.
22 Kalliope is a large M-type asteroid from the asteroid belt discovered by J. R. Hind on 16 November 1852. It is named after Calliope, the Greek Muse of epic poetry. It is orbited by a small moon named Linus.
165 Loreley is a main-belt asteroid that was discovered by C. H. F. Peters on August 9, 1876, in Clinton, New York and named after the Lorelei, a figure in German folklore.
192 Nausikaa is a large main-belt S-type asteroid. It was discovered by Johann Palisa on February 17, 1879, at Pula, then in Austria, now in Croatia. The name derives from Nausicaä, a princess in Homer's Odyssey.
5261 Eureka is the first Mars trojan discovered. It was discovered by David H. Levy and Henry Holt at Palomar Observatory on 20 June 1990. It trails Mars (at the L5 point) at a distance varying by only 0.3 AU during each revolution (with a secular trend superimposed, changing the distance from 1.5–1.8 AU around 1850 to 1.3–1.6 AU around 2400). Minimum distances from Earth, Venus, and Jupiter, are 0.5, 0.8, and 3.5 AU, respectively.
283 Emma is a large asteroid of the asteroid belt and the namesake of the Emma family. It was discovered by Auguste Charlois on 8 February 1889, in Nice, France. The reason for its name is unknown.
379 Huenna is a large asteroid orbiting in the asteroid belt. It is part of the Themis family, and thus a C-type asteroid and consequently composed mainly of carbonaceous material.
617 Patroclus is a large binary Jupiter trojan asteroid. It is a dark D-type asteroid and a slow rotator, due to the 103-hour orbital period of its two components. It is one of five Jupiter trojan asteroids targeted by the Lucy space probe, and is scheduled for a flyby in 2033.
654 Zelinda is a minor planet orbiting the Sun that was discovered on 4 January 1908 by German astronomer August Kopff. On favorable oppositions, it can be as bright as magnitude 10.0, as on January 30, 2016.
679 Pax is a minor planet orbiting the Sun that was discovered by German astronomer August Kopff on January 28, 1909. It is named after Pax, a Roman goddess. It is orbiting the Sun with a period of 4.16 years and an eccentricity of 0.31.
804 Hispania is a minor planet orbiting the Sun. It was discovered from Barcelona (Spain) on 20 March 1915 by Josep Comas Solá (1868–1937), the first asteroid to be discovered by a Spaniard.
854 Frostia is a main-belt asteroid orbiting the Sun. It was discovered in 1916 by Sergei Ivanovich Belyavsky from Simeiz Observatory in Crimea and is named after Edwin Brant Frost, an American astronomer. This asteroid measures approximately 8.4 km (5.2 mi) in diameter.
3749 Balam is a stony Flora asteroid and rare trinary system orbiting in the inner regions of asteroid belt. It also forms a secured asteroid pair with sub-kilometer sized asteroid (312497) 2009 BR60. Balam was discovered on 24 January 1982, by American astronomer Edward Bowell at Lowell's Anderson Mesa Station near Flagstaff, Arizona, and received the prov. designation 1982 BG1. It was named after Canadian astronomer David Balam. Balam measures approximately 4.1 kilometers (2.5 miles) in diameter. Its two minor-planet moons have an estimated diameter of 1.66 and 1.84 kilometers, respectively.
4674 Pauling, provisional designation 1989 JC, is a spheroidal binary Hungaria asteroid from the innermost regions of the asteroid belt, approximately 4.5 kilometers in diameter. It was discovered by American astronomer Eleanor Helin at the U.S. Palomar Observatory, California, on 2 May 1989, and named after the American chemist and Nobel laureate Linus Pauling.
1333 Cevenola, provisional designation 1934 DA, is a binary Eunomian asteroid from the asteroid belt, approximately 15 kilometers in diameter. It was discovered on 20 February 1934, by French astronomer Odette Bancilhon at Algiers Observatory, Algeria in Northern Africa. It was named after the French mountain-range Cévennes, via the Occitan feminine adjective/demonym cevenòla.