12929 Periboea,provisional designation:1999 TZ₁, is a darkJupiter trojan from theTrojan camp, approximately 54 kilometers (34 miles) in diameter. It was discovered on 2 October 1999, by American astronomerCharles W. Juels at theFountain Hills Observatory in Arizona.^[1] Originally considered acentaur, this now re-classified Jovianasteroid has arotation period of 9.3 hours and belongs to the80 largest Jupiter trojans.^[10] It was named from Greek mythology afterPeriboea, mother ofPelagon by the river-godAxius.^[2]

Periboea is a dark Jovianasteroid in a 1:1orbital resonance with Jupiter. It is located in the traileringTrojan camp at the Gas Giant'sL₅Lagrangian point, 60° behind its orbit(seeTrojans in astronomy).^[4] It is also a non-family asteroid of theJovian background population.^[5]

It orbits the Sun at a distance of 5.0–5.4 AU once every 11 years and 12 months (4,378 days;semi-major axis of 5.24 AU). Its orbit has aneccentricity of 0.04 and a highinclination of 43° with respect to theecliptic.^[3] The body'sobservation arc begins with aprecovery taken atPalomar Observatory in September 1953, or 46 years prior to its official discovery observation at Fountain Hills.^[1]

Periboea was originally listed by theMinor Planet Center (MPC) as acentaur. However, its location close to L₅, its low albedo and spectral slope, as well as its estimated dynamical lifetime of more than a billion years, led to the conclusion that the formerly classified centaur is indeed a Jupiter trojan.^[6]

Thisminor planet wasnumbered by the MPC on 22 December 1999 (M.P.C. 22480).^[12] On 14 May 2021, the object was named by theWorking Group for Small Bodies Nomenclature (WGSBN), afterPeriboea, a mortal woman and eldest daughter ofAcessamenus from Greek mythology. Periboea was the mother ofPelagon who she conceived by way of the river godAxius. Her grandson was the Trojan allyAsteropaios.^[2]

Periboea is an assumedC-type asteroid. It has aV–I color index of 0.88.^[10]

In 2007, four rotationallightcurves ofPeriboea have been obtained fromphotometric observations with a period of 10.4 and 10.422 hours (U=2/2/2/2-).^{[6][13][14][15]} Best-rated lightcurve, obtained byStefano Mottola at theCalar Alto Observatory over seven nights from May to June 2009, gave arotation period of9.2749±0.0016 hours with a brightness amplitude of 0.17magnitude (U=2+).^[9][10]

According to the surveys carried out by the JapaneseAkari satellite and theNEOWISE mission of NASA'sWide-field Infrared Survey Explorer, and observations by French and Spanish astronomers,Periboea measures between 51.5 and 55.34 kilometers in diameter and its surface has analbedo between 0.053 and 0.110.^[6][7][8] TheCollaborative Asteroid Lightcurve Link assumes a standard albedo of acarbonaceous asteroid 0.057 and calculates a diameter of 61.04 kilometers based on anabsolute magnitude of 9.8.^[10]

• Asteroid Lightcurve Database (LCDB), query form (infoArchived 16 December 2017 at theWayback Machine)
• Discovery Circumstances: Numbered Minor Planets (10001)-(15000) – Minor Planet Center
• Asteroid (12929) 1999 TZ1Archived 19 June 2018 at theWayback Machine at the Small Bodies Data Ferret
• 12929 Periboea atAstDyS-2, Asteroids—Dynamic Site
  • Ephemeris · Observation prediction · Orbital info · Proper elements · Observational info
• 12929 Periboea at theJPL Small-Body Database
  • Close approach · Discovery · Ephemeris · Orbit viewer · Orbit parameters · Physical parameters

• Minor planet object articles (numbered)
• Jupiter trojans (Trojan camp)
• Discoveries by Charles W. Juels
• Named minor planets
• Astronomical objects discovered in 1999

• Articles with short description
• Short description is different from Wikidata
• Use dmy dates from June 2018
• Webarchive template wayback links
• JPL Small-Body Database ID different from Wikidata