Carpo (moon)

Carpo
	Carpo imaged by the Canada-France-Hawaii Telescope on 25 February 2003
Discovery
Discovered by	Scott S. Sheppard
Discovery site	Mauna Kea Obs.
Discovery date	26 February 2003
Designations
Designation	Jupiter XLVI
Pronunciation	/ˈkɑːrpoʊ/
Named after	Καρπώ Karpō
Alternative names	S/2003 J 20
Adjectives	Carpoan /kɑːrˈpoʊən/ or Carpoian /kɑːrˈpoʊ.iən/
Orbital characteristics
	Epoch 1 January 2000 (JD 2451545.0)
Observation arc	15.25 yr (5,571 d)
Earliest precovery date	9 February 2003
Satellite of	Jupiter
Group	Carpo
Proper orbital elements
Proper semi-major axis	17,042,300 km (0.113921 AU) AU
Proper eccentricity	0.416
Proper inclination	54.0° (to ecliptic)
Proper mean motion	288.174132 deg / yr
Proper orbital period	1.24924 yr; (456.287 d)
Precession of perihelion	N/A arcsec / yr
Precession of the ascending node	11546.8914 arcsec / yr
Physical characteristics
Mean diameter	≈3 km
Albedo	0.04 (assumed)
Apparent magnitude	23.0
Absolute magnitude (H)	16.2

Carpo /ˈkɑːrpoʊ/, also Jupiter XLVI, is a small outer natural satellite of Jupiter. It was discovered by a team of astronomers from the University of Hawaii led by Scott S. Sheppard in 2003, and was provisionally designated as S/2003 J 20^[6]^[7] until it received its name in early 2005.^[8] It was named in March 2005 after Carpo, one of the Horae, and a daughter of Zeus (Jupiter).^[2]

Carpo has a diameter of about 3 km (1.9 mi) for an absolute magnitude of 16.2.^[5]^[4] Like all irregular moons of Jupiter, Carpo's orbit is highly variable over time due to gravitational perturbations by the Sun and other planets.^[9] On average, Carpo's orbit has a semi-major axis of 17.0 million km (10.6 million mi), a high eccentricity of 0.42, and a very high inclination of 54° with respect to the ecliptic.^[5]

Carpo was long thought to be an outlier prograde satellite not part of any group, until S/2018 J 4 was found.^[5] The orbital inclination of satellites such as Carpo is limited by the Kozai effect, which induces a periodic exchange between the inclination and eccentricity of the orbit. If the inclination is large enough, the eccentricity can in turn grow so large that the periapsis of the satellite (called the perijove in the case of moons of Jupiter) would be in the immediate vicinity of the Galilean moons (Io, Europa, Ganymede and Callisto). The satellite would eventually collide with one of these, or a close encounter would eject it altogether from the Jovian system. Due to the Kozai effect, Carpo's argument of periapsis never precesses and instead librates about 90° with respect to the ecliptic, which keeps Carpo's perijove always above Jupiter and its apojove below (see orbit animation below).^[9]

Animation of Carpo's orbit from 2000 to 2100

Polar view

Equatorial view

Jupiter · Carpo · Callisto

References

^ "Planetary Satellite Discovery Circumstances". JPL Solar System Dynamics. NASA. Retrieved 25 January 2023.
^ ^a ^b "Planet and Satellite Names and Discoverers". Gazetteer of Planetary Nomenclature. IAU Working Group for Planetary System Nomenclature. Retrieved 25 January 2023.
^ "Planetary Satellite Mean Elements". JPL Solar System Dynamics. NASA. Retrieved 25 January 2023.
^ ^a ^b ^c ^d "Natural Satellites Ephemeris Service". Minor Planet Center. Retrieved 20 January 2023. Selection of Objects → "All Jovian outer irregular satellites" → Check "I require Orbital Elements" → Get Information
^ ^a ^b ^c ^d ^e ^f Sheppard, Scott S. "Moons of Jupiter". Earth & Planets Laboratory. Carnegie Institution for Science. Retrieved 25 January 2023.
^ Daniel W. E. Green (30 April 2003). "IAUC 8125: S/2003 J 19 and S/2003 J 20". International Astronomical Union. Archived from the original on 5 March 2016.
^ MPEC 2003-G67: S/2003 J 20 2003 April (discovery and ephemeris)
^ Daniel W. E. Green (30 March 2005). "IAUC 8502: Satellites of Jupiter". International Astronomical Union.
^ ^a ^b Brozović, Marina; Jacobson, Robert A. (March 2017). "The Orbits of Jupiter's Irregular Satellites". The Astronomical Journal. 153 (4): 10. Bibcode:2017AJ....153..147B. doi:10.3847/1538-3881/aa5e4d. S2CID 125571053. 147.