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 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.
The core members include :
NameDiameter
Period
Notes
Carme46.7−756.09largest member and group prototype
Taygete5−691.62
Eukelade4−735.03
Eirene3−739.53
Chaldene4−691.25
Isonoe4−727.65
Kalyke6.9−697.41substantially redder than the others
Erinome3−739.53
Aitne3−727.95
Kale2−685.07
Pasithee2−699.28
S/2003 J 9 1
lost

The International Astronomical Union reserves names ending in -e for all retrograde moons.

Origin

The very low dispersion of the mean1 orbital elements among the core members 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.
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.
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
and infrared spectra, similar to D-type asteroids.
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.