A Hecuba-gap asteroid is a member of a
dynamical group
In mathematics, a dynamical system is a system in which a Function (mathematics), function describes the time dependence of a Point (geometry), point in an ambient space. Examples include the mathematical models that describe the swinging of a ...
of resonant
asteroids located in the
Hecuba gap at 3.27
AU – one of the largest
Kirkwood gap
A Kirkwood gap is a gap or dip in the distribution of the semi-major axes (or equivalently of the orbital periods) of the orbits of main-belt asteroids. They correspond to the locations of orbital resonances with Jupiter.
For example, there a ...
s in the
asteroid belt
The asteroid belt is a torus-shaped region in the Solar System, located roughly between the orbits of the planets Jupiter and Mars. It contains a great many solid, irregularly shaped bodies, of many sizes, but much smaller than planets, c ...
, which is considered the borderline separating the
outer main belt asteroid
The asteroid belt is a torus-shaped region in the Solar System, located roughly between the orbits of the planets Jupiter and Mars. It contains a great many solid, irregularly shaped bodies, of many sizes, but much smaller than planets, called ...
s from the
Cybele
Cybele ( ; Phrygian language, Phrygian: ''Matar Kubileya/Kubeleya'' "Kubileya/Kubeleya Mother", perhaps "Mountain Mother"; Lydian language, Lydian ''Kuvava''; el, Κυβέλη ''Kybele'', ''Kybebe'', ''Kybelis'') is an Anatolian mother godde ...
s. A Hecuba-gap asteroid stays in a 2:1
mean motion resonance
In celestial mechanics, orbital resonance occurs when orbiting bodies exert regular, periodic gravitational influence on each other, usually because their orbital periods are related by a ratio of small integers. Most commonly, this relationsh ...
with the gas giant
Jupiter
Jupiter is the fifth planet from the Sun and the largest in the Solar System. It is a gas giant with a mass more than two and a half times that of all the other planets in the Solar System combined, but slightly less than one-thousandth t ...
, which may gradually
perturbe its orbits over a long period until it either intersect with the orbit of
Mars
Mars is the fourth planet from the Sun and the second-smallest planet in the Solar System, only being larger than Mercury. In the English language, Mars is named for the Roman god of war. Mars is a terrestrial planet with a thin at ...
or Jupiter itself. Depending on the dynamical stability of an asteroid's
orbit
In celestial mechanics, an orbit is the curved trajectory of an object such as the trajectory of a planet around a star, or of a natural satellite around a planet, or of an artificial satellite around an object or position in space such as ...
in the Hecuba gap, three subgroups have been proposed. These are the marginally unstable
Griqua asteroids, with an estimated lifetime of more than 100 million years, the stable
Zhongguo asteroids (more than 500 million or even 1 billion years), and an unnamed, strongly unstable population of asteroids with a dynamical lifetime of less than 70 million years.
Moving further out the
Solar System
The Solar System Capitalization of the name varies. The International Astronomical Union, the authoritative body regarding astronomical nomenclature, specifies capitalizing the names of all individual astronomical objects but uses mixed "Solar ...
, the asteroids in the Hecuba gap are followed by the resonant
Cybeles (7:4),
Hilda
Hilda is one of several female given names derived from the name ''Hild'', formed from Old Norse , meaning 'battle'. Hild, a Nordic-German Bellona, was a Valkyrie who conveyed fallen warriors to Valhalla. Warfare was often called Hild's Game. Th ...
s (3:2),
Thule
Thule ( grc-gre, Θούλη, Thoúlē; la, Thūlē) is the most northerly location mentioned in ancient Greek and Roman literature and cartography. Modern interpretations have included Orkney, Shetland, northern Scotland, the island of Saar ...
s (4:3) and
Jupiter trojans (1:1).
Description
Both the Zhongguo (stable) and Griqua asteroids (marginally stable) are also described as the "long-lived" group with lifetimes over 70 million years in order to distinct them from the "short-lived" population. The division between the Griquas and Zhongguo into clearly distinct groups in terms of lifetime has also been questioned and follow-up studies have moved the threshold lifetime between the two long-lived groups from 500 million to 1 billion years.
Griqua asteroids
The Griqua asteroids (also known as the "Griquas") are a
dynamical group
In mathematics, a dynamical system is a system in which a Function (mathematics), function describes the time dependence of a Point (geometry), point in an ambient space. Examples include the mathematical models that describe the swinging of a ...
of
asteroids with marginally unstable
orbit
In celestial mechanics, an orbit is the curved trajectory of an object such as the trajectory of a planet around a star, or of a natural satellite around a planet, or of an artificial satellite around an object or position in space such as ...
s. The group derives its name from the asteroid
1362 Griqua
1362 Griqua, provisional designation is a dark, Jupiter-resonant background asteroid on an eccentric, cometary-like orbit and the namesake of the Griqua group, located in the Hecuba gap in the outermost region of the asteroid belt. The carbonac ...
. The Griquas are located in the
Hecuba gap – one of the largest
Kirkwood gap
A Kirkwood gap is a gap or dip in the distribution of the semi-major axes (or equivalently of the orbital periods) of the orbits of main-belt asteroids. They correspond to the locations of orbital resonances with Jupiter.
For example, there a ...
s in the
asteroid belt
The asteroid belt is a torus-shaped region in the Solar System, located roughly between the orbits of the planets Jupiter and Mars. It contains a great many solid, irregularly shaped bodies, of many sizes, but much smaller than planets, c ...
at 3.27
AU – and stay in a 2:1
mean motion resonance
In celestial mechanics, orbital resonance occurs when orbiting bodies exert regular, periodic gravitational influence on each other, usually because their orbital periods are related by a ratio of small integers. Most commonly, this relationsh ...
with the gas giant
Jupiter
Jupiter is the fifth planet from the Sun and the largest in the Solar System. It is a gas giant with a mass more than two and a half times that of all the other planets in the Solar System combined, but slightly less than one-thousandth t ...
, which gradually
perturbes their orbits over a long period until they either intersect with the orbit of
Mars
Mars is the fourth planet from the Sun and the second-smallest planet in the Solar System, only being larger than Mercury. In the English language, Mars is named for the Roman god of war. Mars is a terrestrial planet with a thin at ...
or Jupiter itself. The group has an estimated lifetime of 100 to (at least) 500 million years. Known members of the Griqua group include ''(articles in boldface)'':
*
1362 Griqua
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3688 Navajo
3688 Navajo, provisional designation , is a Griqua asteroid and a 2:1 Jupiter librator on an eccentric, cometary-like orbit from the outermost regions of the asteroid belt, approximately in diameter. It was discovered on 30 March 1981, by Americ ...
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4177 Kohman
4177 Kohman, provisional designation , is a resonant Griqua asteroid from the outermost regions of the asteroid belt, approximately in diameter. It was discovered on 21 September 1987, by American astronomer Edward Bowell at the Anderson Mesa S ...
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11665 Dirichlet
11665 Dirichlet, provisional designation , is a Griqua asteroid and a 2:1 Jupiter librator from the outermost regions of the asteroid belt, approximately in diameter. It was discovered on 14 April 1997, by astronomer Paul Comba at the Prescott ...
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13963 Euphrates
13963 Euphrates (), provisional designation , is a resonant Griqua asteroid from the outer region of the asteroid belt, approximately 9 kilometers in diameter. It was discovered on 3 August 1991, by Belgian astronomer Eric Elst at ESO's La Silla ...
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Zhongguo asteroids
While the
Griquas
The Griquas (; af, Griekwa, often confused with ''!Orana'', which is written as ''Korana'' or ''Koranna'') are a subgroup of heterogeneous former Khoe-speaking nations in Southern Africa with a unique origin in the early history of the Cap ...
are
asteroids in a marginally unstable orbit, the Zhongguo asteroids (or "Zhongguos"; named after
3789 Zhongguo
3789 Zhongguo, provisional designation ', is a resonant asteroid from outermost region of the asteroid belt, approximately in diameter. It was discovered in 1928 by Chinese astronomer Zhang Yuzhe at the Yerkes Observatory in Williams Bay, Wiscon ...
) are in a rather stable
1:2 resonance with
Jupiter
Jupiter is the fifth planet from the Sun and the largest in the Solar System. It is a gas giant with a mass more than two and a half times that of all the other planets in the Solar System combined, but slightly less than one-thousandth t ...
. The group of 26 identified members, with a lifetime of more than 530 million (or even 1 billion
) years, can be further divided into two clusters in the pseudo-proper element space:
*
3789 Zhongguo
3789 Zhongguo, provisional designation ', is a resonant asteroid from outermost region of the asteroid belt, approximately in diameter. It was discovered in 1928 by Chinese astronomer Zhang Yuzhe at the Yerkes Observatory in Williams Bay, Wisco ...
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11266 Macke
Eleven or 11 may refer to:
*11 (number), the natural number following 10 and preceding 12
* one of the years 11 BC, AD 11, 1911, 2011, or any year ending in 11
Literature
* ''Eleven'' (novel), a 2006 novel by British author David Llewellyn
*''E ...
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11573 Helmholtz
11573 Helmholtz, provisional designation , is a Zhongguo asteroid from the outermost region of the asteroid belt, approximately in diameter. It was discovered on 20 September 1993, by German astronomers Freimut Börngen and Lutz Schmadel at the ...
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14871 Pyramus
14871 Pyramus, provisional designation , is a dark Zhongguo asteroid from the outermost region of the asteroid belt, approximately in diameter. It was discovered on 13 October 1990 by German astronomers Lutz Schmadel and Freimut Börngen at the K ...
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22740 Rayleigh
22740 Rayleigh, provisional designation , is a Zhongguo asteroid from the outermost region of the asteroid belt, approximately in diameter. It was discovered on 20 September 1998, by Belgian astronomer Eric Elst at the La Silla Observatory in Ch ...
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31249 Renéefleming
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45511 Anneblack
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Strongly unstable group
Related but distinct from the "long-lived" Griquas and Zhongguos, is the group of "unstable" Hecuba-gap asteroids:
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1921 Pala
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1922 Zulu
Nineteen or 19 may refer to:
* 19 (number), the natural number following 18 and preceding 20
* one of the years 19 BC, AD 19, 1919, 2019
Films
* ''19'' (film), a 2001 Japanese film
* ''Nineteen'' (film), a 1987 science fiction film
Music ...
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5201 Ferraz-Mello
5201 Ferraz-Mello is an asteroid from the asteroid belt, discovered on 1 December 1983 by Ted Bowell at the Anderson Mesa Station of the Lowell Observatory. It is one of very few Hecuba-gap asteroids located in the 2:1 mean motion resonance wit ...
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5370 Taranis
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Year 537 ( DXXXVII) was a common year starting on Thursday (link will display the full calendar) of the Julian calendar. At the time, it was known as the Second year after the Consulship of Belisarius (or, less frequently, year 1290 ...
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8373 Stephengould
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9767 Midsomer Norton
9767 Midsomer Norton () is an Outer asteroid belt, outer main-belt asteroid discovered on March 10, 1992, by Duncan Steel at Siding Spring Observatory, Siding Spring. It is one of very few asteroids located in the 2:1 orbital resonance, mean motion ...
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65541 Kasbek
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In 2005, further research expanded this group of 16 bodies with an additional 31 multi-opposition asteroids, that show life-times of less than 70 million years. It is also thought that approximately 25% of the short-lived population are "extremely unstable" with lifetimes of less than 2 million years.
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Among the unstable population, some asteroids have such a high
eccentricity
Eccentricity or eccentric may refer to:
* Eccentricity (behavior), odd behavior on the part of a person, as opposed to being "normal"
Mathematics, science and technology Mathematics
* Off-Centre (geometry), center, in geometry
* Eccentricity (g ...
with a
perihelion
An apsis (; ) is the farthest or nearest point in the orbit of a planetary body about its primary body. For example, the apsides of the Earth are called the aphelion and perihelion.
General description
There are two apsides in any elli ...
of less than 1.3 AU, that qualifies them as a
near-Earth object
A near-Earth object (NEO) is any small Solar System body whose orbit brings it into proximity with Earth. By convention, a Solar System body is a NEO if its closest approach to the Sun (perihelion) is less than 1.3 astronomical units (AU). ...
. These five bodies (with their current eccentricity taken from the
JPL SBDB
The JPL Small-Body Database (SBDB) is an astronomy database about small Solar System bodies. It is maintained by Jet Propulsion Laboratory (JPL) and NASA and provides data for all known asteroids and several comets, including orbital parameters an ...
in parenthesis) are
5370 Taranis
__NOTOC__
Year 537 ( DXXXVII) was a common year starting on Thursday (link will display the full calendar) of the Julian calendar. At the time, it was known as the Second year after the Consulship of Belisarius (or, less frequently, year 1290 ...
(0.64), (0.65), (0.70), (0.66), (0.72).
References
External links
On the Origin of the Long-Lived Asteroids in the 2:1 Mean-Motion Resonance with Jupiter 8-slide presentation, Chrenko, 2014
Dynamics of the Solar System – Publication overview Miroslav Broz, Institute of Astronomy, Charles University
orbital diagram
www.projectpluto.com
{{Small Solar System bodies
*