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 orbital inclinations between 164.9° and 165.5°, and their orbital eccentricities between 0.23 and 0.27 (with one exception).

The core members include (from largest to smallest):
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, ISBN 0-521-81808-7, 2004, p. 263 - 280 [http://www.ifa.hawaii.edu/~jewitt/papers/JUPITER/JSP.2003.pdf Full text(pdf).] ] David Nesvorný, Cristian Beaugé, and Luke Dones"Collisional Origin of Families of Irregular Satellites", The Astronomical Journal, 127 (2004), pp. 1768–1783 [http://www.boulder.swri.edu/~davidn/papers/irrbig.pdf Full text.] ]
* Carme (the largest, which gives its name to the group)
* Taygete
* EukeladeListed by Nesvorny 2004 as a "possible" member, not listed by Sheppard 2004; the orbital elements confirmed by Jacobson 2004]
* S/2003 J 5
* Chaldene
* Isonoe
* Kalyke (substantially redder than the others)
* Erinome
* Aitne
* Kale
* Pasithee
* S/2003 J 9
* S/2003 J 10

The International Astronomical Union (IAU) reserves names in -e for all retrograde moons, including this group's members.

Origin

The very low dispersion of the mean¹ orbital elements among the core members (the group is separated by less than 700,000km in semi major axis and less than 0.7° in inclination) suggests that the Carme group may once have been a single body that was broken apart by an impact. The dispersion can be explained by a very small velocity impulse (5 < δV < 50 m/s). David Nesvorný, Jose L. A. Alvarellos, Luke Dones, and Harold F. Levison"Orbital and Collisional Evolution of the Irregular Satellites", The Astronomical Journal,126 (2003), pages 398–429. [http://www.journals.uchicago.edu/AJ/journal/issues/v126n1/202528/202528.web.pdf (pdf)] ] The parent body was probably about the size of Carme, 46 km in diameter; 99% of the group's mass is still located in Carme. [cite journal
last = Sheppard
first = Scott S.
authorlink = Scott S. Sheppard
coauthors = Jewitt, David C.
title = An abundant population of small irregular satellites around Jupiter
journal = Nature
volume = 423
pages = 261–263
date = May 5 2003
doi = 10.1038/nature01584 ]

Further support to the single body origin comes from the known colours: all² the satellites appear light red, with colour indices B-V= 0.76 and V-R= 0.47 Grav, Tommy; Holman, Matthew J.; Gladman, Brett J.; Aksnes, Kaare "Photometric survey of the irregular satellites", Icarus, 166,(2003), pp. 33-45. [http://arxiv.org/abs/astro-ph/0301016 Preprint] ] and infrared spectra, similar to D-type asteroids.Tommy Grav and Matthew J. Holman"Near-Infrared Photometry of the Irregular Satellites of Jupiter and Saturn",The Astrophysical Journal, 605, (2004), pp. L141–L144 [http://arxiv.org/abs/astro-ph/0312571 Preprint] ] These data are consistent with a progenitor from the Hilda family or a Jupiter Trojan.

¹Osculating orbital parameters of irregular satellites of Jupiter change widely in short intervals due to heavy perturbation by Jupiter. For example, changes of as much as 1 Gm in semi-major axis in 2 years, 0.5 in eccentricity in 12 years, and as much as 5° in 24 years have been reported. Mean orbital elements are the averages calculated by the numerical integration of current elements over a long period of time, used to determine the dynamical families.²With the exception of Kalyke, substantially redder.

References