2001/12/19 by S. Wachter, Stefanie Wachter, D. W. Hoard +4 · 7 citations
Physics and Astronomy · #Astronomy #Astrophysical Phenomena and Observations #Astrophysics #Computer science #Gamma-ray bursts and supernovae #Optics #Physics #Pulsars and Gravitational Waves Research #Term (time) #Transient (computer programming) #X-ray #X-ray transient #astro-ph
paper · pdf · doi:10.1086/339034
26 pages, 10 figures, ApJ, in press
arxiv created 2001/12/19 · openalex publication_date 2002/04/01 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
We report long-term simultaneous optical and (RXTE) X-ray observations of the soft X-ray transient and low mass X-ray binary X1608-52 spanning from 1999 to 2001. In addition to the usual X-ray outburst and quiescent states, X1608-52 also exhibits an extended low intensity state during which the optical counterpart, QX Nor, is found to be about two magnitudes brighter than during quiescence. We detect optical photometric variability on a possible period of 0.5370 days with a semi-amplitude of ~0.27 mag in the I band. The modulation could be orbital but is also consistent with a scenario invoking a superhump with decreasing period. Observations of QX Nor during quiescence indicate an F to G type main sequence secondary while theoretical considerations argue for an evolved mass donor. Only an evolved mass donor would satisfy the condition for the occurrence of superhumps.