Himalia group

Last updated
This diagram compares the orbital elements and relative sizes of the largest four members of the Himalia group. The horizontal axis illustrates their average distance from Jupiter, the vertical axis their orbital inclination, and the circles their relative sizes. TheIrregulars JUPITER Himalia.svg
This diagram compares the orbital elements and relative sizes of the largest four members of the Himalia group. The horizontal axis illustrates their average distance from Jupiter, the vertical axis their orbital inclination, and the circles their relative sizes.
This diagram illustrates all the irregular satellites of Jupiter. The Himalia group is bunched together near the top of the diagram. An object's position on the horizontal axis indicates its distance from Jupiter. The vertical axis indicates its inclination. Eccentricity is indicated by yellow bars illustrating the object's maximum and minimum distances from Jupiter. Circles illustrate an object's size in comparison to the others. TheIrregulars JUPITER GROUPS.svg
This diagram illustrates all the irregular satellites of Jupiter. The Himalia group is bunched together near the top of the diagram. An object's position on the horizontal axis indicates its distance from Jupiter. The vertical axis indicates its inclination. Eccentricity is indicated by yellow bars illustrating the object's maximum and minimum distances from Jupiter. Circles illustrate an object's size in comparison to the others.

The Himalia group is a group of prograde irregular satellites of Jupiter that follow similar orbits to Himalia and are thought to have a common origin. [1]

The known members of the group are (in order of increasing distance from Jupiter):

NameDiameter
(km)
Period
(days)
Notes
Leda 21.5240.93
Ersa 3249.23
Himalia 139.6
(150×120)
250.56largest member and group prototype
S/2018 J 2 3250.88
Pandia 3251.91
Lysithea 42.2259.20
Elara 79.9259.64
S/2011 J 3 3261.77
Dia 4278.21

Two additional possible satellites discovered by Sheppard in 2017 have been identified to be likely part of the Himalia group, but were too faint ( mag >24) to be tracked and confirmed as satellites. [2]

The International Astronomical Union (IAU) reserves names for moons of Jupiter ending in -a (Leda, Himalia and so on) for the moons in this group to indicate prograde motions of these bodies relative to Jupiter, their gravitationally central object. [3]

Characteristics and origin

The objects in the Himalia group have semi-major axes (distances from Jupiter) in the range of 11.10 and 12.30 Gm, inclinations between 27.2° and 29.1°, and eccentricities between 0.11 and 0.24. All orbit in a prograde direction. In physical appearance, the group is very homogeneous, all satellites displaying neutral colours (colour indices B−V = 0.66 and V−R = 0.36) similar to those of C-type asteroids. Given the limited dispersion of the orbital parameters and the spectral homogeneity, it has been suggested that the group could be a remnant of the break-up of an asteroid from the main asteroid belt. [4] The radius of the parent asteroid was probably about 89 km, only slightly larger than that of Himalia, which retains approximately 87% of the mass of the original body. This indicates the asteroid was not heavily disturbed. [1]

Numerical integrations show a high probability of collisions among the members of the prograde group during the lifespan of the solar system (e.g. on average 1.5 collisions between Himalia and Elara). In addition, the same simulations have shown fairly high probabilities of collisions between prograde and retrograde satellites (e.g. Pasiphae and Himalia have a 27% probability of collision within 4.5 gigayears). Consequently, it has been suggested that the current group could be a result of a more recent, rich collisional history among the prograde and retrograde satellites as opposed to the single break-up shortly after the planet formation that has been inferred for the Carme and Ananke groups. [5]

Related Research Articles

<span class="mw-page-title-main">Carme (moon)</span> Moon of Jupiter

Carme is a retrograde irregular satellite of Jupiter. It was discovered by Seth Barnes Nicholson at Mount Wilson Observatory in California in July 1938. It is named after the mythological Carme, mother by Zeus of Britomartis, a Cretan goddess.

<span class="mw-page-title-main">Lysithea (moon)</span> Outer moon of Jupiter

Lysithea is a prograde irregular satellite of Jupiter. It was discovered by Seth Barnes Nicholson in 1938 at Mount Wilson Observatory and is named after the mythological Lysithea, daughter of Oceanus and one of Zeus' lovers.

<span class="mw-page-title-main">Natural satellite</span> Astronomical body that orbits a planet

A natural satellite is, in the most common usage, an astronomical body that orbits a planet, dwarf planet, or small Solar System body. Natural satellites are colloquially referred to as moons, a derivation from the Moon of Earth.

<span class="mw-page-title-main">Leda (moon)</span> Outer moon of Jupiter

Leda, also known as Jupiter XIII, is a prograde irregular satellite of Jupiter. It was discovered by Charles T. Kowal at the Mount Palomar Observatory on September 14, 1974, after three nights' worth of photographic plates had been taken. It was named after Leda, who was raped by Zeus, the Greek equivalent of Jupiter. Kowal suggested the name and the IAU endorsed it in 1975.

<span class="mw-page-title-main">Himalia (moon)</span> Moon of Jupiter (Jupiter VI)

Himalia, also known as Jupiter VI, is the largest irregular satellite of Jupiter. With a diameter of at least 140 km (90 mi), it is the sixth largest Jovian satellite, after the four Galilean moons and Amalthea. It was discovered by Charles Dillon Perrine at the Lick Observatory on 3 December 1904 and is named after the nymph Himalia, who bore three sons of Zeus. It is one of the largest planetary moons in the Solar System not imaged in detail, and the third largest not imaged in detail within the orbit of Neptune.

<span class="mw-page-title-main">Elara (moon)</span> Outer moon of Jupiter

Elara is a prograde irregular satellite of Jupiter. It was discovered by Charles Dillon Perrine at Lick Observatory in 1905 in photographs taken with the 36" Crossley reflecting telescope which he had recently rebuilt. It is the eighth-largest moon of Jupiter and is named after Elara, one of Zeus's lovers and the mother of the giant Tityos.

<span class="mw-page-title-main">Ananke (moon)</span> Moon of Jupiter

Ananke is a retrograde irregular moon of Jupiter. It was discovered by Seth Barnes Nicholson at Mount Wilson Observatory in 1951. It is named after the Greek mythological Ananke, the personification of necessity, and the mother of the Moirai (Fates) by Zeus. The adjectival form of the name is Anankean.

<span class="mw-page-title-main">Pasiphae (moon)</span> Moon of Jupiter

Pasiphae, formerly spelled Pasiphaë, is a retrograde irregular satellite of Jupiter. It was discovered in 1908 by Philibert Jacques Melotte and later named after the mythological Pasiphaë, wife of Minos and mother of the Minotaur from Greek legend.

<span class="mw-page-title-main">Sinope (moon)</span> Moon of Jupiter

Sinope is a retrograde irregular satellite of Jupiter discovered by Seth Barnes Nicholson at Lick Observatory in 1914, and is named after Sinope of Greek mythology.

<span class="mw-page-title-main">Themisto (moon)</span> Outer moon of Jupiter

Themisto, also known as Jupiter XVIII, is a small prograde irregular satellite of Jupiter. It was discovered in 1975, subsequently lost, and rediscovered in 2000.

<span class="mw-page-title-main">Moons of Jupiter</span> Natural satellites of the planet Jupiter

There are 95 moons of Jupiter with confirmed orbits as of 5 February 2024. This number does not include a number of meter-sized moonlets thought to be shed from the inner moons, nor hundreds of possible kilometer-sized outer irregular moons that were only briefly captured by telescopes. All together, Jupiter's moons form a satellite system called the Jovian system. The most massive of the moons are the four Galilean moons: Io, Europa, Ganymede, and Callisto, which were independently discovered in 1610 by Galileo Galilei and Simon Marius and were the first objects found to orbit a body that was neither Earth nor the Sun. Much more recently, beginning in 1892, dozens of far smaller Jovian moons have been detected and have received the names of lovers or daughters of the Roman god Jupiter or his Greek equivalent Zeus. The Galilean moons are by far the largest and most massive objects to orbit Jupiter, with the remaining 91 known moons and the rings together comprising just 0.003% of the total orbiting mass.

<span class="mw-page-title-main">Skathi (moon)</span> Satellite of Saturn

Skathi, also named Saturn XXVII and originally spelled Skadi, is a natural satellite of the planet Saturn. Skathi is one of Saturn's irregular moons, in its Norse group of satellites. It was discovered on September 23, 2000, by a team of astronomers led by Brett Gladman. The team announced their discovery on December 7, 2000, along with seven other satellites of Saturn, namely; Tarvos, Ijiraq, Thrymr, Siarnaq, Mundilfari, Erriapus, and Suttungr. The moon was named after Skaði, a figure in Norse mythology, as part of an effort to diversify the largely Greek and Roman names of astronomical objects.

<span class="mw-page-title-main">Moons of Uranus</span> Natural satellites of the planet Uranus

Uranus, the seventh planet of the Solar System, has 28 confirmed moons. Most of them are named after characters that appear in, or are mentioned in, the works of William Shakespeare and Alexander Pope. Uranus's moons are divided into three groups: thirteen inner moons, five major moons, and ten irregular moons. The inner and major moons all have prograde orbits and are cumulatively classified as regular moons. In contrast, the orbits of the irregular moons are distant, highly inclined, and mostly retrograde.

<span class="mw-page-title-main">Moons of Neptune</span> Natural satellites of the planet Neptune

The planet Neptune has 16 known moons, which are named for minor water deities and a water creature in Greek mythology. By far the largest of them is Triton, discovered by William Lassell on 10 October 1846, 17 days after the discovery of Neptune itself. Over a century passed before the discovery of the second natural satellite, Nereid, in 1949, and another 40 years passed before Proteus, Neptune's second-largest moon, was discovered in 1989.

<span class="mw-page-title-main">Ananke group</span> Group of retrograde irregular satellites of Jupiter

The Ananke group is a group of retrograde irregular satellites of Jupiter that follow similar orbits to Ananke and are thought to have a common origin.

<span class="mw-page-title-main">Carme group</span> Group of satellites orbiting Jupiter

The Carme group is a group of retrograde irregular satellites of Jupiter that follow similar orbits to Carme and are thought to have a common origin.

<span class="mw-page-title-main">Irregular moon</span> Captured satellite following an irregular orbit

In astronomy, an irregular moon, irregular satellite, or irregular natural satellite is a natural satellite following a distant, inclined, and often highly elliptical and retrograde orbit. They have been captured by their parent planet, unlike regular satellites, which formed in orbit around them. Irregular moons have a stable orbit, unlike temporary satellites which often have similarly irregular orbits but will eventually depart. The term does not refer to shape; Triton, for example, is a round moon but is considered irregular due to its orbit and origins.

<span class="mw-page-title-main">Retrograde and prograde motion</span> Relative directions of orbit or rotation

Retrograde motion in astronomy is, in general, orbital or rotational motion of an object in the direction opposite the rotation of its primary, that is, the central object. It may also describe other motions such as precession or nutation of an object's rotational axis. Prograde or direct motion is more normal motion in the same direction as the primary rotates. However, "retrograde" and "prograde" can also refer to an object other than the primary if so described. The direction of rotation is determined by an inertial frame of reference, such as distant fixed stars.

<span class="mw-page-title-main">Valetudo (moon)</span> Outer moon of Jupiter

Valetudo, also known as Jupiter LXII and originally known as S/2016 J 2, is an irregular moon of Jupiter. It was discovered by Scott S. Sheppard and his team in data acquired by the 6.5-m Magellan-Baade telescope of the Las Campanas Observatory in 2016, but was not announced until 17 July 2018, via a Minor Planet Electronic Circular from the Minor Planet Center, which also reported the discovery of nine other of Jupiter's moons. Besides data from Las Campanas, the original announcement also referred to data acquired through the 8.1-m Gemini North telescope of the Mauna Kea Observatories as well as the 4.0-m reflector of the Cerro Tololo Inter-American Observatory.

<span class="mw-page-title-main">Ersa (moon)</span> Outer moon of Jupiter

Ersa, also designated Jupiter LXXI, is a small outer natural satellite of Jupiter discovered by Scott S. Sheppard on 11 May 2018, using the 4.0-meter Víctor M. Blanco Telescope at Cerro Tololo Observatory, Chile. It was announced alongside nine other Jovian moons on 17 July 2018 and was provisionally designated S/2018 J 1 by the Minor Planet Center, after observations were collected over a long enough time span to confirm the satellite's orbit. The satellite has been found in precovery observations as early as 6 August 2000.

References

  1. 1 2 Scott S. Sheppard, David C. Jewitt An abundant population of small irregular satellites around Jupiter, Nature, 423 (May 2003), pp.261-263 (pdf) Archived 2006-08-13 at the Wayback Machine
  2. Sheppard, Scott; Williams, Gareth; Tholen, David; Trujillo, Chadwick; Brozovic, Marina; Thirouin, Audrey; et al. (August 2018). "New Jupiter Satellites and Moon-Moon Collisions". Research Notes of the American Astronomical Society. 2 (3): 155. arXiv: 1809.00700 . Bibcode:2018RNAAS...2..155S. doi: 10.3847/2515-5172/aadd15 . S2CID   55052745. 155.
  3. Antonietta Barucci, M. (2008). "Irregular Satellites of the Giant Planets" (PDF). In M. Antonietta Barucci; Hermann Boehnhardt; Dale P. Cruikshank; Alessandro Morbidelli (eds.). The Solar System Beyond Neptune. University of Arizona Press. p. 414. ISBN   9780816527557. Archived from the original (PDF) on 10 August 2017. Retrieved 22 July 2017.
  4. Grav, Tommy; Holman, Matthew J.; Gladman, Brett; Aksnes, Kaare (2003-01-02). "Photometric Survey of the Irregular Satellites". Icarus . 166: 33–45. Retrieved 2024-01-09 via ArXiv.
  5. David Nesvorný, Cristian Beaugé, and Luke Dones Collisional Origin of Families of Irregular Satellites, The Astronomical Journal, 127 (2004), pp. 1768–1783 (pdf).