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 an orbit that is irregular in some of the following ways: Distant; inclined; highly elliptical; retrograde. They have often be ...
s of
Jupiter
Jupiter is the fifth planet from the Sun and the List of Solar System objects by size, largest in the Solar System. It is a gas giant with a Jupiter mass, mass more than 2.5 times that of all the other planets in the Solar System combined a ...
that follow similar
orbit
In celestial mechanics, an orbit (also known as orbital revolution) 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 ...
s to
Pasiphae and are thought to have a common origin.
Their
semi-major axes (distances from Jupiter) range between 22.6 and 24.3 million km (similar 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 22.7 and 23.6 Gm, their orbital ...
), 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 141.5° and 157.3°, and their
eccentricities between 0.22 and 0.44.
The members of the Pasiphae group are:
[ Scott S. Sheppard, 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; , UAI) is an international non-governmental organization (INGO) with the objective of advancing astronomy in all aspects, including promoting astronomical research, outreach, education, and developmen ...
(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
An asteroid is a minor planet—an object larger than a meteoroid that is neither a planet nor an identified comet—that orbits within the Solar System#Inner Solar System, inner Solar System or is co-orbital with Jupiter (Trojan asteroids). As ...
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 centre of the circle and whose endpoints lie on the circle. It can also be defined as the longest Chord (geometry), chord of the circle. Both definitions a ...
, 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%.
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 in color class between the objects (grey for Pasiphae, light red for 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