Pasiphae group

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This diagram illustrates the largest irregular satellites of Jupiter. Among the Pasiphae group, Sinope and Pasiphae itself are labelled. 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 the largest irregular satellites of Jupiter. Among the Pasiphae group, Sinope and Pasiphae itself are labelled. 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 Pasiphae group is a group of retrograde irregular satellites of Jupiter that follow similar orbits to Pasiphae and are thought to have a common origin.

Contents

Their semi-major axes (distances from Jupiter) range between 22.6 and 24.3 million km (similar range as the Carme group), their inclinations between 141.5° and 157.3°, and their eccentricities between 0.22 and 0.44.

The International Astronomical Union (IAU) reserves names ending in -e for all retrograde moons, which includes all those in the Pasiphae group.

Origin

For most of the 20th century, there were only eight known irregular satellites orbiting Jupiter, half of them prograde (Himalia, Elara, Lysithea, and Leda) and half of them retrograde (Pasiphae, Carme, Sinope, and Ananke). [1] It was thought that the progrades and retrogrades each formed their own group, with each group being associated with their own collisional family, or even that all eight satellites all shared a single collisional origin. [2] These proposals were hard to support and were replaced by alternative theories as new moons were discovered. [1]

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, 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%. [3]

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, which also causes some moons to be later reassigned to different groups as time goes on. [4] [note 1] It is suggested sometimes that Sinope might be not a part of the remnants of the same collision and captured independently instead. [5] [3] [6] 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. [5]

This diagram compares the orbital elements and relative sizes of the core members of the Pasiphae group. The horizontal axis illustrates their average distance from Jupiter, the vertical axis their orbital inclination, and the circles their relative sizes. TheIrregulars JUPITER Pasiphae CORE i.svg
This diagram compares the orbital elements and relative sizes of the core members of the Pasiphae 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 Pasiphae group (red) with the more compact Ananke (blue) and Carme (green) groups. TheIrregulars JUPITER Pasiphae i.svg
This diagram compares the wide dispersion of the Pasiphae group (red) with the more compact Ananke (blue) and Carme (green) groups.

List

The members of the Pasiphae group are (in order by date announcement): [7]

NameDiameter
(km) [8] 		Semi-Major Axis
(km) [9] 		Period
(days) [9] [note 2] 		Notes
Pasiphae 5823463200–734.42largest member and group prototype
Sinope 3823679300–744.60red colour
Callirrhoe 723789400–749.79reddish colour
Megaclite 623640100–752.86reddish colour
Autonoe 423785200–749.61
Eurydome 322894500–707.86
Sponde 223538700–737.95
S/2003 J 4 222922300–709.12
Aoede 423773100–749.07
Hegemone 323342600–728.77
Cyllene 223650000–743.21has come within 9.2 million km of Jupiter
Kore 224203300–769.42can reach 38.5 million km from Jupiter
Philophrosyne 222600200–694.20
S/2003 J 23 223824000–751.40
S/2011 J 2 122903400–708.29
S/2017 J 1 223739600–747.44
S/2017 J 6 223251200–724.47
S/2016 J 4 123113900–718.04

Notes

  1. ↑ Nesvorný 2003, concurring on the Ananke and Carme groups, lists only Megaclite for Pasiphae. 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. [1]
  2. ↑ Negative periods are indicative of retrograde motion.

References

  1. 1 2 3 Nesvorný, David; Beaugé, Cristian; Dones, Luke (March 2004). "Collisional Origin of Families of Irregular Satellites". The Astronomical Journal. 127 (3): 1768–1783. Bibcode: 2004AJ....127.1768N . doi: 10.1086/382099 . ISSN   0004-6256.
  2. ↑ Nesvorný, David; Alvarellos, Jose L. A.; Dones, Luke; Levison, Harold F. (July 2003). "Orbital and Collisional Evolution of the Irregular Satellites". The Astronomical Journal. 126 (1): 398–429. Bibcode: 2003AJ....126..398N . doi: 10.1086/375461 . ISSN   0004-6256.
  3. 1 2 Sheppard, Scott S.; Jewitt, David C. (May 5, 2003). "An abundant population of small irregular satellites around Jupiter" (PDF). Nature. 423 (6937): 261–263. Bibcode:2003Natur.423..261S. doi:10.1038/nature01584. PMID   12748634. S2CID   4424447.
  4. ↑ Gao, Fabao; Liu, Xia (5 August 2020). "Revisiting the distributions of Jupiter's irregular moons: II. orbital characteristics". arXiv: 2003.04851v3 [astro-ph.EP].
  5. 1 2 Grav, Tommy; Holman, Matthew J.; Gladman, Brett; Aksnes, Kaare (2003-01-02). "Photometric Survey of the Irregular Satellites". Icarus . 166 (1): 33–45. arXiv: astro-ph/0301016 . Bibcode: 2003Icar..166...33G . doi:10.1016/j.icarus.2003.07.005.
  6. ↑ Sheppard, Scott S.; Tholen, David J.; Alexandersen, Mike; Trujillo, Chadwick A. (2023-05-24). "New Jupiter and Saturn Satellites Reveal New Moon Dynamical Families". Research Notes of the AAS. 7 (5): 100. Bibcode: 2023RNAAS...7..100S . doi: 10.3847/2515-5172/acd766 . ISSN   2515-5172.
  7. ↑ Sheppard, Scott S.; Jewitt, David C.; Porco, Carolyn (2004). "Jupiter's outer satellites and Trojans" (PDF). In Bagenal, Fran; Dowling, Timothy E.; McKinnon, William B. (eds.). Jupiter. The planet, satellites and magnetosphere. Cambridge planetary science. Vol. 1. Cambridge, UK: Cambridge University Press. pp. 263–280. ISBN   0-521-81808-7. Archived from the original (PDF) on 2007-06-14.
  8. ↑ Scott S. Sheppard. "Moons of Jupiter". Scott S. Sheppard Carnegie Science. Retrieved 25 January 2024.
  9. 1 2 "Planetary Satellite Mean Elements". Jet Propulsion Laboratory. Retrieved 25 January 2024.
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