5258 Rhoeo,provisional designation:1989 AU₁, is aJupiter trojan and member of theEurybates family from theGreek camp, approximately 53 kilometers (33 miles) in diameter. It was discovered on 1 January 1989, by Japanese astronomerYoshiaki Oshima at theGekko Observatory, east of Shizuoka, Japan.^[1] The assumedC-type asteroid belongs to the90 largest Jupiter trojans and has arotation period of 19.9 hours.^[6] It was named from Greek mythology afterRhoeo, lover of Apollo and mother of his sonAnius.^[2]

Rhoeo is a dark Jovianasteroid orbiting in the leading Greek camp at Jupiter'sL₄Lagrangian point, 60° ahead of the Gas Giant's orbit in a1:1 resonance(seeTrojans in astronomy).^[4][10] It orbits the Sun at a distance of 4.8–5.6 AU once every 11 years and 9 months (4,303 days;semi-major axis of 5.18 AU). Its orbit has aneccentricity of 0.08 and aninclination of 6° with respect to theecliptic.^[3] The body'sobservation arc begins with its official discovery observation at Gekko Observatory in January 1989.^[1]

Rhoeo is the member of the smallEurybates family (005),^[5] named after its parent body,3548 Eurybates. Thisasteroid family comprises 218 known members of carbonaceous and/or primitive composition,^[11]: 23 and is one of only a few families identified among the Jovian asteroids; with four of them in the Greek camp. This potentially collisional family was first characterized by Jakub Rozehnal and Miroslav Brož in 2011, and further described in 2014.^[12][13] Other members of this family include the Jupiter trojans8060 Anius,9818 Eurymachos,(163189) 2002 EU6,(287577) 2003 FE42 and360072 Alcimedon.^[11] In theHCM analysis by Milani and Knežević, however,Rhoeo belongs to thebackground population.^[10]

Thisminor planet wasnumbered by theMinor Planet Center on 14 July 1992 (M.P.C. 20492).^[14] On 14 May 2021, the object was named by theWorking Group for Small Bodies Nomenclature (WGSBN), afterRhoeo from Greek mythology, who became the lover of Apollo and by him the mother ofAnius. When her father discovered her pregnancy, he believed she was impregnated by a man rather than a god. He placed her in a chest and cast her out to sea. Anius later prophesied the decade-long siege of Troy.^[2]

Rhoeo is an assumed, carbonaceousC-type asteroid.^[6] The overallspectral type of members of the Eurybates family is that of a C- andP-type.^[11]: 23 It has a highV–I color index of 1.01.^[6]

In April 2015, the so-far onlylightcurve was obtained byRobert Stephens at theCenter for Solar System Studies in Landers, California. Thephotometric observations gave arotation period of19.85±0.05 hours and a brightness variation of 0.14 magnitude (U=2+).^[6][8][a]

According to the survey carried out by theNEOWISE mission of NASA'sWide-field Infrared Survey Explorer,Rhoeo measures 53.28 kilometers in diameter and its surface has analbedo of 0.052,^[7] while theCollaborative Asteroid Lightcurve Link assumes a standard albedo for a carbonaceous asteroid of 0.057 and calculates a diameter of 50.77 kilometers based on anabsolute magnitude of 10.2.^[6]

• Long-term evolution of asteroid families among Jovian Trojans, Jakub Rozehnal and Miroslav Brož (2014)
• Asteroid Lightcurve Database (LCDB), query form (infoArchived 16 December 2017 at theWayback Machine)
• Discovery Circumstances: Numbered Minor Planets (5001)-(10000) – Minor Planet Center
• 5258 Rhoeo atAstDyS-2, Asteroids—Dynamic Site
  • Ephemeris · Observation prediction · Orbital info · Proper elements · Observational info
• 5258 Rhoeo at theJPL Small-Body Database
  • Close approach · Discovery · Ephemeris · Orbit viewer · Orbit parameters · Physical parameters

• Minor planet object articles (numbered)
• Jupiter trojans (Greek camp)
• Eurybates asteroids
• Discoveries by Yoshiaki Oshima
• Named minor planets
• Astronomical objects discovered in 1989

• CS1 maint: multiple names: authors list
• Articles with short description
• Short description is different from Wikidata
• Use dmy dates from June 2018
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