The Pasiphae group is a group of
retrograde irregular satellite
In astronomy, an irregular moon, irregular satellite or irregular natural satellite is a natural satellite following a distant, inclined, and often eccentric and retrograde orbit. They have been captured by their parent planet, unlike regular s ...
s of
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 ...
that follow similar
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 to
Pasiphae and are thought to have a common origin.
Their
semi-major axes (distances from Jupiter) range between 22.8 and 24.1 million km (the same range as the
Carme group
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.
Their semi-major axes (distances from Jupiter) range between 22.9 and 24.1 Gm, their orbit ...
), their
inclination
Orbital inclination measures the tilt of an object's orbit around a celestial body. It is expressed as the angle between a reference plane and the orbital plane or axis of direction of the orbiting object.
For a satellite orbiting the Eart ...
s between 144.5° and 158.3°, and their
eccentricities between 0.25 and 0.43.
Core members of the group include (negative periods indicate retrograde orbits):
Scott S. Sheppard
Scott Sander Sheppard (born 1977) is an American astronomer and a discoverer of numerous moons, comets and minor planets in the outer Solar System.
He is an astronomer in the Department of Terrestrial Magnetism at the Carnegie Institution for Scie ...
, David C. Jewitt, Carolyn Porco
''Jupiter's outer satellites and Trojans'', In: ''Jupiter. The planet, satellites and magnetosphere.'' Edited by Fran Bagenal, Timothy E. Dowling, William B. McKinnon. Cambridge planetary science, Vol. 1, Cambridge, UK: Cambridge University Press, , 2004, p. 263 - 28
Full text(pdf).
The
International Astronomical Union
The International Astronomical Union (IAU; french: link=yes, Union astronomique internationale, UAI) is a nongovernmental organisation with the objective of advancing astronomy in all aspects, including promoting astronomical research, outreac ...
(IAU) reserves names ending in -e for all retrograde moons.
Origin
The Pasiphae group is believed to have been formed when Jupiter captured an
asteroid which subsequently broke up after a collision. The original asteroid was not disturbed heavily: the original body is calculated to have been 60 km in
diameter
In geometry, a diameter of a circle is any straight line segment that passes through the center of the circle and whose endpoints lie on the circle. It can also be defined as the longest chord of the circle. Both definitions are also valid fo ...
, about the same size as Pasiphae; Pasiphae retains 99% of the original body's mass. However, if
Sinope belongs to the group, the ratio is much smaller, 87%.
[
However, Nesvorny 2003, while concurring on the Ananke and Carme groups, lists only Megaclite for Pasiphae's group]
Unlike the
Carme and
Ananke groups, the theory of a single impact origin for the Pasiphae group is not accepted by all studies. This is because the Pasiphae group, while similar in semi-major axis, is more widely dispersed in inclination. Alternatively, Sinope might be not a part of the remnants of the same collision and captured independently instead.
[Grav, Tommy; Holman, Matthew J.; Gladman, Brett J.; Aksnes, Kaare ''Photometric survey of the irregular satellites'', Icarus, 166,(2003), pp. 33-45]
Preprint
/ref> The differences of colour between the objects (grey for Pasiphae, light red for Callirrhoe Callirrhoe (, grc, Καλλιρρόη; also Callirhoe) may refer to:
* Callirhoe (mythology), several figures in Greek mythology, including:
** Callirrhoe (Oceanid), daughter of Oceanus and Tethys
** Callirrhoe (daughter of Achelous)
* Callirrhoe ...
and Megaclite) also suggest that the group could have a more complex origin than a single collision.
Notes
References
{{DEFAULTSORT:Pasiphae group
Moons of Jupiter
Irregular satellites
Moons with a retrograde orbit