2017A&A...607A..96M


C.D.S. - SIMBAD4 rel 1.7 - 2020.05.28CEST03:40:40

2017A&A...607A..96M - Astronomy and Astrophysics, volume 607A, 96-96 (2017/11-1)

A modern study of HD 166734: a massive supergiant system.

MAHY L., DAMERDJI Y., GOSSET E., NITSCHELM C., EENENS P., SANA H. and KLOTZ A.

Abstract (from CDS):

Aims. HD 166734 is an eccentric eclipsing binary system composed of two supergiant O-type stars, orbiting with a 34.5-day period. In this rare configuration for such stars, the two objects mainly evolve independently, following single-star evolution so far. This system provides a chance to study the individual parameters of two supergiant massive stars and to derive their real masses.
Methods. An intensive monitoring was dedicated to HD 166734. We analyzed mid- and high-resolution optical spectra to constrain the orbital parameters of this system. We also studied its light curve for the first time, obtained in the VRI filters. Finally, we disentangled the spectra of the two stars and modeled them with the CMFGEN atmosphere code in order to determine the individual physical parameters.
Results. HD 166734 is a O7.5If+O9I(f) binary. We confirm its orbital period but we revise the other orbital parameters. In comparison to what we found in the literature, the system is more eccentric and, now, the hottest and the most luminous component is also the most massive one. The light curve exhibits only one eclipse and its analysis indicates an inclination of 63.0°±2.7°. The photometric analysis provides us with a good estimation of the luminosities of the stars, and therefore their exact positions in the Hertzsprung-Russell diagram. The evolutionary and the spectroscopic masses show good agreement with the dynamical masses of 39.5M for the primary and 33.5M for the secondary, within the uncertainties. The two components are both enriched in helium and in nitrogen and depleted in carbon. In addition, the primary also shows a depletion in oxygen. Their surface abundances are however not different from those derived from single supergiant stars, yielding, for both components, an evolution similar to that of single stars.

Abstract Copyright: © ESO, 2017

Journal keyword(s): stars: early-type - binaries: general - stars: fundamental parameters - stars: individual: HD 166734 - stars: individual: HD 166734

VizieR on-line data: <Available at CDS (J/A+A/607/A96): table.dat sp/*>

Status at CDS:  

Simbad objects: 3

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Number of rows : 3

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2020
#notes
1 RMC 139 WR* 05 38 42.3548071421 -69 04 58.201053806   12.04 11.94     O6.5Iafc+O6Iaf 86 0
2 WR 21a WR* 10 25 56.5023591737 -57 48 43.517827393     12.67     O2If*/WN5 80 0
3 HD 166734 s*b 18 12 24.6552422490 -10 43 53.059483541 9.36 9.49 8.42 7.33 6.47 O7.5Iabf 154 0

    Equat.    Gal    SGal    Ecl

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2020.05.28-03:40:40

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