J/A+A/607/A96 HD 166734 ESPRESSO spectra (Mahy+, 2017)
A modern study of HD166734: a massive supergiant system.
Mahy L., Damerdji Y., Gosset E., Nitschelm C., Eenens P., Sana H., Klotz A.
<Astron. Astrophys. 607, A96 (2017)>
=2017A&A...607A..96M 2017A&A...607A..96M (SIMBAD/NED BibCode)
ADC_Keywords: Stars, early-type - Stars, supergiant ; Binaries, eclipsing ;
Spectroscopy
Keywords: stars: early-type - binaries: general -
stars: fundamental parameters - stars: individual: HD 166734
Abstract:
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. 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. 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
Description:
ESPRESSO spectra of HD166734.
Objects:
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RA (2000) DE Designation(s)
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18 12 24.66 -10 43 53.0 HD 166734 = HIP 89218
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table.dat 32 70 List of spectra
sp/* . 70 Individual fits spectra
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Byte-by-byte Description of file: table.dat
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Bytes Format Units Label Explanations
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1- 2 A2 --- Num Sequential number of the spectrum
3- 15 A13 --- HJD Heliocentric Julian Date
16- 32 A17 --- FileName Spectrum filename in subdirectory sp
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Acknowledgements:
Laurent Mahy, mahy(at)astro.ulg.ac.be
(End) Patricia Vannier [CDS] 12-Sep-2017