The Pasiphaë group is a group of retrograde irregular satellites of Jupiter that follow similar orbits to Pasiphaë and are thought of have a common origin. In Astronomy, an irregular moon is a Natural satellite following a distant inclined, and often retrograde Orbit. In Physics, an orbit is the gravitationally curved path of one object around a point or another body for example the gravitational orbit of a planet around a star TemplateInfobox Planet.--> Pasiphaë (, or as in Greek Πασιφάη

Their semi-major axes (distances from Jupiter) range between 22. In Geometry, the semi-major axis (also semimajor axis) is used to describe the dimensions of ellipses and hyperbolae 8 and 24. 1 million km (the same range as the Carme group), their inclinations between 144. 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 Inclination in general is the Angle between a Reference plane and another plane or axis of direction 5° and 158. 3°, and their eccentricities between 0. In Astrodynamics, under standard assumptions, any Orbit must be of Conic section shape 25 and 0. 43.

This diagram illustrates the largest irregular satellites of Jupiter. Among the Pasiphaë group, Sinope and Pasiphaë itself are labelled. An object's position on the horizontal axis indicates its distance from Jupiter. The vertical axis indicates its inclination. Inclination in general is the Angle between a Reference plane and another plane or axis of direction Eccentricity is indicated by yellow bars illustrating the object's maximum and minumum distances from Jupiter. In Astrodynamics, under standard assumptions, any Orbit must be of Conic section shape Circles illustrate an object's size in comparison to the others.

Core members of the group include (from the largest to the smallest):^[1]

• Pasiphae
• Sinope, two-thirds the size of Pasiphaë
• Callirrhoe
• Megaclite
• Autonoe
• Eurydome
• Sponde

The International Astronomical Union (IAU) reserves names ending in -e for all retrograde moons, including this group's members. TemplateInfobox Planet.--> Pasiphaë (, or as in Greek Πασιφάη TemplateInfobox Planet.--> Sinope (, or as in Greek Σινώπη Callirrhoe ( kə-LIRR-oh-ee or as in Greek Καλλιρρόη also known as Jupiter XVII, is one of Jupiter 's outermost named Megaclite ( MEG-ə-KLYE-tee or as in Latin Megaclītē from Greek Μεγακλειτη also known as Jupiter XIX Autonoe ( aw-TON-oh-ee or as in Greek Αυτονόη also known as Jupiter XXVIII, is a Natural satellite of Jupiter Eurydome ( ew-RID-ə-mee or as in Greek Ευριδομη also known as Jupiter XXXII, is a Natural satellite of Jupiter This article is about the astronomical body For the French poet see Jean de Sponde; for the Metrical foot, see Spondee.

Origin

The Pasiphaë group is believed to have been formed when Jupiter captured an asteroid which subsequently broke up after a collision. Asteroids, sometimes called Minor planets or planetoids', are bodies—primarily of the inner Solar System —that are smaller than planets but The original asteroid was not disturbed heavily: the original body is calculated to have been 60 km in diameter, about the same size as Pasiphaë; Pasiphaë retains 99% of the original body's mass. Geometry, a diameter of a Circle is any straight Line segment that passes through the center of the circle and whose Endpoints are on the However, if Sinope belongs to the group, the ratio is much smaller, 87%. TemplateInfobox Planet.--> Sinope (, or as in Greek Σινώπη ^[2]

Unlike the Carme and Ananke groups, the theory of a single impact origin for the Pasiphaë group is not accepted by all studies. 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 The Ananke group is a group of Retrograde Irregular satellites of Jupiter that follow similar Orbits to Ananke and are thought to have This is because the Pasiphaë group, while similar in semi-major axis is more widely dispersed in inclination ¹ . However, Secular resonances, known for both Pasiphae and Sinope, could shape the orbits and provide the explanation for the post-collision dispersal of the orbital elements. A secular resonance is a type of Orbital resonance. Secular resonances occur when the precession of two orbits is synchronised (a precession of the Perihelion ^[3] Alternatively, Sinope might be not a part of the remnants of the same collision and captured independently instead. ^[4]

The differences of colour between the objects (grey for Pasiphaë, light red for Callirrhoe and Megaclite) also suggest that the group could have a more complex origin than a single collision. Callirrhoe ( kə-LIRR-oh-ee or as in Greek Καλλιρρόη also known as Jupiter XVII, is one of Jupiter 's outermost named Megaclite ( MEG-ə-KLYE-tee or as in Latin Megaclītē from Greek Μεγακλειτη also known as Jupiter XIX ^[4]

This diagram compares the orbital elements and relative sizes of the core members of the Pasiphaë group. The horizontal axis illustrates their average distance from Jupiter, the vertical axis their orbital inclination, and the circles their relative sizes.

This diagram compares the wide dispersion of the Pasiphaë group (red) with the more compact Ananke (blue) and Carme (green) groups.

¹ Nesvorny 2003, concurring on Ananke and Carme groups, lists only Megaclithe for Pasiphae

[edit] References

1. ^ Scott S. Sheppard, David C. Jewitt, Carolyn Porco Jupiter's outer satellites and Trojans, In: Jupiter. The Pasiphaë group is a group of Retrograde Irregular satellites of Jupiter that follow similar Orbits to Pasiphaë and are thought Scott S Sheppard is an Astronomer in the Department of Terrestrial Magnetism at the Carnegie Institution for Science. David C Jewitt is a Professor of Astronomy at the University of Hawaii Institute for Astronomy. Carolyn Porco (born March 6 1953 in New York City) is an American planetary scientist known for 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, ISBN 0-521-81808-7, 2004, p. 263 - 280 Full text(pdf).
2. ^ Sheppard, Scott S.; Jewitt, David C. (May 5, 2003). Scott S Sheppard is an Astronomer in the Department of Terrestrial Magnetism at the Carnegie Institution for Science. David C Jewitt is a Professor of Astronomy at the University of Hawaii Institute for Astronomy. Events 553 - The Second Council of Constantinople begins 1215 - Rebel Barons renounce their allegiance to King John Year 2003 ( MMIII) was a Common year starting on Wednesday of the Gregorian calendar. "An abundant population of small irregular satellites around Jupiter". Nature 423: 261–263. doi:doi:10.1038/nature01584. A digital object identifier ( DOI) is a permanent identifier given to an Electronic document.   However, Nesvorny 2003, while concurring on the Ananke and Carme groups, lists only Megaclithe for Pasiphaë's group
3. ^ David Nesvorný, Cristian Beaugé, and Luke Dones Collisional Origin of Families of Irregular Satellites, The Astronomical Journal, 127 (2004), pp. 1768–1783 Full text.
4. ^ ^{a b} Grav, Tommy; Holman, Matthew J. ; Gladman, Brett J. ; Aksnes, Kaare Photometric survey of the irregular satellites, Icarus, 166,(2003), pp. 33-45. Preprint