J/A+A/601/A34 Resolved astrometry of ten O-type binaries (Le Bouquin+, 2017)
Resolved astrometric orbits of ten O-type binaries.
Le Bouquin J.-B., Sana H., Gosset E., De Becker M., Duvert G., Absil O.,
Anthonioz F., Berger J.-P., Ertel S., Grellmann R., Guieu S., Kervella P.,
Rabus M., Willson M.
<Astron. Astrophys. 601, A34 (2017)>
=2017A&A...601A..34L 2017A&A...601A..34L (SIMBAD/NED BibCode)
ADC_Keywords: Stars, double and multiple ; Binaries, orbits ; Stars, O
Keywords: stars: massive - binaries: general - methods: observational -
techniques: high angular resolution
Abstract:
Our long-term aim is to derive model-independent stellar masses and
distances for long period massive binaries by combining apparent
astrometric orbit with double-lined radial velocity amplitudes
(SB2).We followed-up ten O+O binaries with AMBER, PIONIER and GRAVITY
at the VLTI. Here, we report on 130 astrometric observations over the
last seven years. We combined this dataset with distance estimates to
compute the total mass of the systems. We also computed preliminary
individual component masses for the five systems with available SB2
radial velocities. Nine of the ten binaries have their
three-dimensional orbit well constrained. Four of them are known to be
colliding wind, non-thermal radio emitters, and thus constitute
valuable targets for future high angular resolution radio imaging. Two
binaries break the correlation between period and eccentricity
tentatively observed in previous studies. This suggests either that
massive star formation produces a wide range of systems, or that
several binary formation mechanisms are at play. Finally, we found
that the use of existing SB2 radial velocity amplitudes can lead to
unrealistic masses and distances.If not understood, the biases in
radial velocity amplitudes will represent an intrinsic limitation for
estimating dynamical masses from SB2+interferometry or SB2+Gaia.
Nevertheless, our results can be combined with future Gaia astrometry
to measure the dynamical masses and distances of the individual
components with an accuracy of 5 to 15%, completely independently of
the radial velocities.
Description:
Individual resolved astrometric position for the 10 O-type binaries,
obtained with optical long baseline interferometry at the VLTI.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
stars.dat 35 10 List of studied stars
position.dat 67 138 Astrometric measurements
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Byte-by-byte Description of file: stars.dat
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Bytes Format Units Label Explanations
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1- 10 A10 --- Target Target name
13- 14 I2 h RAh Simbad Right ascension (J2000)
16- 17 I2 min RAm Simbad Right ascension (J2000)
19- 23 F5.2 s RAs Simbad Right ascension (J2000)
25 A1 --- DE- Simbad Declination sign (J2000)
26- 27 I2 deg DEd Simbad Declination (J2000)
29- 30 I2 arcmin DEm Simbad Declination (J2000)
32- 35 F4.1 arcsec DEs Simbad Declination (J2000)
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Byte-by-byte Description of file: position.dat
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Bytes Format Units Label Explanations
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1- 10 A10 --- Target Target name
12- 21 A10 "date" Night Observing night (1)
23- 31 F9.3 d MJD Modified Julian Day
33- 39 F7.3 mas Sep Apparent separation (2)
41- 47 F7.3 deg PA Position angle (2)
49- 55 F7.3 mas emax Major axis of error ellipse (3)
57- 63 F7.3 mas emin Minor axis of error ellipse (3)
65- 67 I3 deg PAemax Position angle of emax of error ellipse (3)
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Note (1): The Night column corresponds to the UT date at Paranal at the
beginning of the night (ESO archive convention).
Note (2): The separation and position angle are the position of the secondary
(faintest in H band) with respect to the primary (brightest in H
band), measured east (90 deg) from north (0 deg).
Note (3): The columns emax and emin are the FWHM of the major and minor axes of
the astrometric error ellipse. The column PAemax is the position
angle of the major axis.
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Acknowledgements:
Jean-Baptiste Le Bouquin, jean-baptiste.lebouquin(at)obs.ujf-grenoble.fr
(End) J.-B. Le Bouquin [IPAG, France], P. Vannier [CDS] 20-Aug-2016