Refinement of third body parameters and new photometric results for the early-type multiple system IU Aurigae^*

¹ Çanakkale Onsekiz Mart University, Department of Physics, 17100 Çanakkale, Turkey
² Çanakkale Astrophysics Research Center, Terzioğlu Campus, 17100 Çanakkale, Turkey
³ Astronomical Institute, Charles University, Švédská 8, 15000 Praha 5, Czech Republic
⁴ Dr. Remeis-Sternwarte, Astronomisches Institut der Universtät Erlangen-Nürnberg, Sternwartstrasse 7, 96049 Bamberg, Germany
⁵ Ankara University, Department of Astronomy and Space Sciences, 06100 Ankara, Turkey

Corresponding author: S. Özdemir, ozdemir@comu.edu.tr

Received: 3 January 2003
Accepted: 7 March 2003

Abstract

The massive eclipsing binary system IU Aurigae is re-analyzed in the context of new photometric observations and an improved treatment of its long-term period changes (O–C diagram) derived from new times of minima. The best-fit of the O–C curve reveals that the third component is orbiting around the system with a period of 293.3 days in a highly eccentric orbit (). A solution of the most recent UBV light curves obtained during 1997/1998 showed a third light contribution of ≈23% and continuation of the orbital plane precession of IU Aurigae. Since the revised mass of the third component deduced from the analysis of the O–C curve of   would imply a larger fraction of third light than suggested by the value of 23% derived from the light curve analysis, the third body is possibly composed of two components. A q-search test applied to the UBV light curves yields a minimum  value at , which confirms previous photometric and spectroscopic solutions.