Title

Dynamical modelling of CXOGBS J175553.2-281633: a 10 h long orbital period cataclysmic variable

Author ORCID Identifier

Salinas, Ricardo 0000-0002-1206-1930

Heinke, Craig 0000-0003-3944-6109

Document Type

Article

Publication Date

3-2021

Abstract

We present modelling of the long-term optical light and radial velocity curves of the binary stellar system CXOGBS J175553.2-281633, first detected in X-rays in the Chandra Galactic Bulge Survey. We analysed 7 yr of optical I-band photometry from Optical Gravitational Lensing Experiment and found long-term variations from year to year. These long-term variations can most likely be explained with by either variations in the luminosity of the accretion disc or a spotted secondary star. The phased light curve has a sinusoidal shape, which we interpret as being due to ellipsoidal modulations. We improve the orbital period to be P = 10.34488 +/- 0.00006 h with a time of inferior conjunction of the secondary star T-0 = HJD2455260.8204 +/- 0.0008. Moreover, we collected 37 spectra over 6 non-consecutive nights. The spectra show evidence for an evolved K7 secondary donor star, from which we obtain a semi-amplitude for the radial velocity curve of K-2 = 161 +/- 6 km s(-1). Using the light-curve synthesis code xrbinary, we derive the most likely orbital inclination for the binary of i = 63.0 +/- 0.7 deg, a primary mass of M-1 = 0.83 +/- 0.06 M-circle dot, consistent with a white dwarf accretor, and a secondary donor mass of M-2 = 0.65 +/- 0.07 M-circle dot, consistent with the spectral classification. Therefore, we identify the source as a long orbital period cataclysmic variable star.

Publication Source (Journal or Book title)

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY

First Page

48

Last Page

59

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