Callirrhoe (moon)

Callirrhoe
	This discovery image of Callirrhoe taken by Spacewatch in October 1999
Discovery
Discovered by	Spacewatch
Discovery site	Kitt Peak National Observatory
Discovery date	19 October 1999
Designations
Designation	Jupiter XVII
Pronunciation	/kəˈlɪroʊiː/
Named after	Καλλιρρόη Kallirrhoê
Alternative names	S/1999 J 1; 1999 UX18
Orbital characteristics
	Epoch 27 April 2019 (JD 2458600.5)
Observation arc	17.54 yr (6,406 days)
Semi-major axis	0.1643278 AU (24,583,090 km)
Eccentricity	0.3095704
Orbital period (sidereal)	–787.43 d
Mean anomaly	240.90203°
Mean motion	0° 27m 25.866s / day
Inclination	147.99790° (to ecliptic)
Longitude of ascending node	352.75480°
Argument of perihelion	68.21981°
Satellite of	Jupiter
Group	Pasiphae group
Physical characteristics
Mean diameter	9.6±1.3 km
Albedo	0.052±0.016
Apparent magnitude	20.8
Absolute magnitude (H)	13.92±0.02

Callirrhoe (/kəˈlɪroʊ.iː/; Greek: Καλλιρρόη), also known as Jupiter XVII, is one of Jupiter's outer natural satellites. It is an irregular moon that orbits in a retrograde direction. Callirrhoe was imaged by Spacewatch at Kitt Peak National Observatory from October 6 through November 4, 1999,^[8] and originally designated as asteroid 1999 UX₁₈.^[9]^[10] It was discovered to be in orbit around Jupiter by Tim Spahr on July 18, 2000, and then given the designation S/1999 J 1.^[1]^[11] It was the 17th confirmed moon of Jupiter.^[8]

Name

Stack of three images taken by the VLT in July 2000, showing Callirrhoe's movement relative to background stars

It was named in October 2002 after Callirrhoe, daughter of the river god Achelous, one of Zeus's (Jupiter's) many conquests.^[12]

Characteristics

Callirrhoe has an apparent magnitude of 20.8,^[7] making it even fainter than dwarf planet Eris at magnitude 18.7.^[13] Jupiter is about 2.1 billion times brighter than Callirrhoe.^[b]

Callirrhoe is about 9.6 kilometers in diameter,^[6] and orbits Jupiter at an average distance of 24.1 million kilometers in 747.09 days, at an inclination of 141° to the ecliptic (140° to Jupiter's equator) with an eccentricity of 0.28. This object was probably captured long ago from a heliocentric orbit and the Sun's gravitational influence makes this orbit highly erratic.^[8]

It belongs to the Pasiphae group, irregular retrograde moons orbiting Jupiter at distances ranging between 22.8 and 24.1 million kilometers, and with inclinations ranging between 144.5° and 158.3°. However, while Pasiphae is gray (B−V=0.74, V−R=0.38, V−I=0.74) in color, Callirrhoe is light red (B−V=0.72, V−R=0.50, V−I=1.02) and more similar to Megaclite.^[14]

Exploration

As a navigation exercise, the New Horizons spacecraft imaged Callirrhoe on January 10, 2007.^[15]

Notes

^ The discovery is credited to the team of astronomers consisting of J. V. Scotti, T. B. Spahr, R. S. McMillan, J. A. Larson, J. Montani, A. E. Gleason, and T. Gehrels.^[2]
^ ${\sqrt[{5}]{100^{13.92-\left(-9.4\right)}}}\approx 2.13\times 10^{9}$

References

^ ^a ^b Brian G. Marsden (20 July 2000). "IAUC 7460: S/1999 J 1". IAU. Archived from the original on 26 April 2006. Retrieved 22 November 2005.
^ "Planet and Satellite Names and Discoverers". Gazetteer of Planetary Nomenclature. USGS Astrogeology Science Center. Retrieved 26 November 2020.
^ Noah Webster (1884). A Practical Dictionary of the English Language.
^ "Pasiphae". Dictionary.com Unabridged (Online). n.d.
^ "M.P.C. 115890" (PDF). Minor Planet Circular. Minor Planet Center. 27 August 2019.
^ ^a ^b ^c ^d Grav, T.; Bauer, J. M.; Mainzer, A. K.; Masiero, J. R.; Nugent, C. R.; Cutri, R. M.; et al. (August 2015). "NEOWISE: Observations of the Irregular Satellites of Jupiter and Saturn" (PDF). The Astrophysical Journal. 809 (1): 9. Bibcode:2015ApJ...809....3G. doi:10.1088/0004-637X/809/1/3. S2CID 5834661. 3.
^ ^a ^b Sheppard, Scott. "Scott S. Sheppard - Jupiter Moons". Department of Terrestrial Magnetism. Carnegie Institution for Science. Retrieved 26 November 2020.
^ ^a ^b ^c "New Outer Satellite of Jupiter Discovered". Minor Planet Center. Retrieved 23 July 2009.
^ "New moon of Jupiter found". SpaceFlight Now (University of Arizona News Release). Retrieved 23 July 2009.
^ MPS 7418 (Minor Planet Circulars Supplement); not available on-line
^ MPEC 2000-Y16: S/1975 J 1 = S/2000 J 1, S/1999 J 1 2000-12-19 (discovery and ephemeris)
^ IAUC 7998: Satellites of Jupiter 2002 October 22 (naming the moon)
^ "AstDys (136199) Eris Ephemerides". Department of Mathematics, University of Pisa, Italy. Retrieved 16 March 2009.
^ Grav, Tommy; Holman, M. J.; Gladman, B. J.; Aksnes, K. (2003). "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. S2CID 7793999.
^ "New Horizons Jupiter Encounter Timeline". www.planetary.org.