Physical parameters and ±0.2% parallax of the detached eclipsing binary V923 Scorpii
Authors:
Pribulla, T. et al.
Image & caption:
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Image caption::
Closure phases (left column) and squared visibilities (right column) of V923 Sco measured with GRAVITY (VLTI) on 2 July 2017. The best fit CANDID binary star model is represented with red curves in each panel. The recorded spectrum is also shown in the upper left panel before and after the correction of the telluric absorption lines.
Description:
The paper presents new observations of a bright and nearby southern eclipsing binary V923 Sco. The authors obtained for the object precise satellite photometry (MOST), which showed presence of a grazing secondary eclipse with a depth of only 13 mmag. A new long-baseline interferometry of V923 Sco enabled to resolve the binary at 9 epochs. Simultaneous analysis of position measurement, radial velocities, photometric observations as well as flux ratios obtained in several wavelength bands led to high-accuracy orbital elements a absolute parameters of the components. The most important result is direct determination of the object's distance comparing the projected size of the visual and spectroscopic orbit. The corresponding parallax, π = 16.018 ± 0.009 mas, was later independently confirmed by the Gaia DR2 ( π = 16.070 ± 0.054 mas). The result confirms the reliability of Gaia parallaxes even for objects close to the brightness limit of the satellite (V = 5.91).
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