Open AccessOptical studies of the X‐ray transient XTE J2123−058 – I. Photometry
Author(s) -
Zurita C.,
Casares J.,
Shahbaz T.,
Charles P. A.,
Hynes R. I.,
Shugarov S.,
Goransky V.,
Pavlenko E. P.,
Kuznetsova Y.
Publication year - 2000
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1046/j.1365-8711.2000.03502.x
Subject(s) - physics , photometry (optics) , light curve , astrophysics , orbital period , amplitude , x ray transient , astronomy , orbital inclination , accretion disc , binary number , optics , stars , neutron star , arithmetic , mathematics
We present optical photometry of the X‐ray transient XTE J2123−058, obtained in 1998 July–October. The light curves are strongly modulated on the 5.95‐h orbital period, and exhibit dramatic changes in amplitude and form during the decline. We used synthetic models, which include the effect of partial eclipses and X‐ray heating effects, to estimate the system parameters, and we constrain the binary inclination to be i =73°±4. The model is successful in reproducing the light curves at different stages of the decay by requiring the accretion disc to become smaller and thinner by 30 per cent as the system fades by 1.7 mag in the optical. From August 26 the system reaches quiescence with a mean magnitude of R =21.7±0.1 and our data are consistent with the optical variability being dominated by the ellipsoidal modulation of the companion.