J/A+A/616/A75 Triple system HD150136 radial velocities (Mahy+, 2018)
The triple system HD150136: From periastron passage to actual masses.
Mahy L., Gosset E., Manfroid J., Nitschelm C., Herve A., Semaan T.,
Sana H., Lebouquin J.-B., Toonen S.
<Astron. Astrophys. 616, A75 (2018)>
=2018A&A...616A..75M 2018A&A...616A..75M (SIMBAD/NED BibCode)
ADC_Keywords: Stars, early-type ; Stars, double and multiple ; Radial velocities
Keywords: stars: early-type - binaries: spectroscopic -
stars: fundamental parameters - stars: individual: HD150136
Abstract:
The triple system HD 150136 is composed of an O3 V((f*))-O3.5
V((f+)) primary, of an O5.5-6 V((f)) secondary and of a more distant
O6.5-7 V((f)) tertiary. The latter component went through periastron
in 2015-2016, an event that will not occur again within the next eight
years. We aim to analyse the tertiary periastron passage to determine
the orbital properties of the outer system, to constrain its
inclination and its eccentricity, and to determine the actual masses
of the three components of the system. We conducted an intensive
spectroscopic monitoring of the periastron passage of the tertiary
component and combined them with new interferometric measurements.
This allows us to derive the orbital solution of the outer orbit in
three-dimensional space. We also obtained the light curve of the
system to further constrain the inclination of the inner binary. We
determine an orbital period of 8.61±0.02 years, an eccentricity of
0.682±0.002, and an inclination of 106.18±0.14° for the outer
orbit. The actual masses of the inner system and of the tertiary
object are 72.32-8.49+8.45M☉ and
15.54-4.97+4.96M☉, respectively. From the mass of the inner
system and accounting for the known mass ratio between the primary and
the secondary, we determine actual masses of 42.81M☉ and
29.51M☉ for the primary and the secondary components,
respectively. We infer, from the different mass ratios and the
inclination of the outer orbit, an inclination of 62.4° for the
inner system. This value is confirmed by photometry. Grazing eclipses
and ellipsoidal variations are detected in the light curve of HD
150136. We also compute the distance of the system to
1.096±0.274kpc. By combining spectroscopy, interferometry, and
photometry, HD 150136 offers us a unique chance to compare theory and
observations. The masses estimated through our analysis are smaller
than those constrained by evolutionary models. The formation of this
triple system suggests similar ages for the three components within
the errorbars. Finally, we show that Lidov-Kozai cycles have no effect
on the evolution of the inner binary, which suggests that the latter
will experience mass transfer leading to a merger of the two stars.
Description:
Journal of observations and radial velocity measurements.
We collected and retrieved 177 optical spectra of HD 150136 obtained
with the Fibre-fed Extended Range Optical Spectrograph (FEROS) mounted
successively on the ESO 1.52 m (for observations before 2002) and on
the MPG/ESO 2.2 m (for observations after 2002) telescopes at La Silla
observatory (Chile). These data were partially presented and analysed
in Mahy et al. (2012A&A...540A..97M 2012A&A...540A..97M) and in Sana et al.
(2013A&A...553A.131S 2013A&A...553A.131S) but spectra that were newly acquired around the
periastron passage of the third component are introduced in the
present paper.
We also obtained Director's Discretionary Time (DDT) with the
UV-Visual Echelle Spectrograph (UVES; PI: Mahy 297.D-5007, PI: Gosset
295.D-5025, and PI: Gosset 294.D-5041) mounted on the ESO-VLT to
acquire eight additional spectra, which we have completed with two
additional spectra provided by the EDIBLES team (see Cox et al. 2017;
PI: Cox; Large Programme: 194.C-0833(C)) taken in June and July 2015.
Finally, we took three spectra of HD 150136 with the CORALIE
spectrograph mounted on the Swiss 1.2m Leonhard Euler telescope at La
Silla. CORALIE is an improved version of the ELODIE spectrograph
covering the spectral range between 3850 and 6890Å.
Objects:
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RA (2000) DE Designation(s)
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16 41 20.42 -48 45 46.7 HD 150136 = HR 6187
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
hd150136.dat 58 190 Journal of observations and RVs
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Byte-by-byte Description of file: hd150136.dat
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Bytes Format Units Label Explanations
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1- 11 A11 "date" Obs.Date Date of the observation
13- 19 A7 --- Inst Instrument (1)
21- 28 F8.3 --- HJD Heliocentric Julian Date (HJD-2450000)
32- 38 F7.2 km/s RV1 Radial velocity of the primary
42- 48 F7.2 km/s RV2 Radial velocity of the secondary
52- 58 F7.2 km/s RV3 Radial velocity of the tertiary
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Note (1): 177 FEROS, 10 UVES and 3 CORALIE observations.
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Acknowledgements:
Laurent Mahy, mahy(at)astro.ulg.ac.be
(End) Patricia Vannier [CDS] 24-May-2018