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The Eclipsing Triple System U Ophiuchi Revisited – poster 094

Symposium 240 BINARY STARS AS CRITICAL TOOLS AND TESTS IN CONTEMPORARY ASTROPHYSICS Luiz Paulo R. Vaz – UFMG - Brazil Johannes Andersen – Copenhagen University - Denmark Antônio Claret – IAA – Spain.

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The Eclipsing Triple System U Ophiuchi Revisited – poster 094

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  1. Symposium 240 BINARY STARS AS CRITICAL TOOLS AND TESTS IN CONTEMPORARY ASTROPHYSICS Luiz Paulo R. Vaz – UFMG - Brazil Johannes Andersen – Copenhagen University - Denmark Antônio Claret – IAA – Spain The Eclipsing Triple System U Ophiuchi Revisited – poster 094

  2. U Ophiuchi - Motivation • Mid B-type (~5Msun) on the Main Sequence • Eclipsing system (P ~ 1.67 d) • Triple system (P3 ~ 38.4 yr) • Apsidal motion (U ~ 21.2 yr) • Opportunity to improve absolute dimensions determination and to test evolutionary models

  3. Spectroscopic analysis • Photographic spectra from ESO 1.5m • Primary with stronger and broader lines • New ephemeris (including apsidal motion and light-time orbit) fully accounted for in the analysis

  4. Photometric analysis • uvbyHβ SAT observations • HR6412 detected as eclipsing • Wilson-Devinney simultaneous solutions: 4 LCs (uvby) + 2 RVs (pri/sec) and fully account for the ephemeris • Both traditional least-squares and SIMPLEX minimization methods

  5. Apsidal Motion and light-time orbit • Lacy (1992) exact method for apsidal motion, implemented with time-light effect Irwin 1952, 1959 • 353 times of minima (229 pri, 124 sec) carefully selected from 512 (334 pri, 178 sec) individual times from literature from 1882 to 2004

  6. New ephemeris • Radial velocity and light curves taken at different dates (and orbital configurations) analized simultaneously

  7. Absolute Dimensions

  8. Evolutionary status and comparison with other systems • U Oph is well fitted with Z=0.02, Y=0.28 • MU Cas and V760 Sco seem to require Z=0.01 • Difficult to assign ages with models, coevality is the key • DI Her is still a puzzle (too young, too long apsidal motion period)

  9. Conclusions • Claret and Padova models give different ages, but are consistent with respect to coevality • The chemical diversity of these young systems (all younger than 100Myr old) presents a challenge to models of galactic chemical evolution

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