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.
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 members of the Pasiphae group are (in order by date announcement): [1]
Name | Diameter (km) [2] | Semi-Major Axis (km) | Period (days) [3] [note 1] | Notes |
---|---|---|---|---|
Pasiphae | 58 | 23463200 | –734.42 | largest member and group prototype |
Sinope | 38 | 23679300 | –744.60 | red colour |
Callirrhoe | 7 | 23789400 | –749.79 | reddish colour |
Megaclite | 6 | 23640100 | –752.86 | reddish colour |
Autonoe | 4 | 23785200 | –749.61 | |
Eurydome | 3 | 22894500 | –707.86 | |
Sponde | 2 | 23538700 | –737.95 | |
S/2003 J 4 | 2 | 22922300 | –709.12 | |
Aoede | 4 | 23773100 | –749.07 | |
Hegemone | 3 | 23342600 | –728.77 | |
Cyllene | 2 | 23650000 | –743.21 | |
Kore | 2 | 24203300 | –769.42 | |
Philophrosyne | 2 | 22600200 | –694.20 | |
S/2003 J 23 | 2 | 23824000 | –751.40 | |
S/2011 J 2 | 1 | 22903400 | –708.29 | |
S/2017 J 1 | 2 | 23739600 | –747.44 | |
S/2017 J 6 | 2 | 23251200 | –724.47 | |
S/2016 J 4 | 1 | 23113900 | –718.04 |
The International Astronomical Union (IAU) reserves names ending in -e for all retrograde moons.
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%. [4]
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. [note 2] Alternatively, Sinope might be not a part of the remnants of the same collision and captured independently instead. [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. [6]