2015/07/01 by Pasi Hakala, Hakala, Pasi, Gavin Ramsay +5
Physics and Astronomy · #FOS: Physical sciences #High Energy Astrophysical Phenomena (astro-ph.HE) #Solar and Stellar Astrophysics (astro-ph.SR) #astro-ph.HE #astro-ph.SR
paper · pdf · doi:10.48550/arxiv.1507.00149
6 pages, 6 figures, Accepted for publication in MNRAS letters 2015 June 30. Received in original form 2015 May 19
arxiv created 2015/07/27 · arxiv updated 2015/07/28
Sco X-1 is the archetypal low mass X-ray binary (LMXB) and the brightest persistent extra-solar X-ray source in the sky. It was included in the K2 Campaign 2 field and was observed continuously for 71 days with 1 minute time resolution. In this paper we report these results and underline the potential of K2 for similar observations of other accreting compact binaries. We reconfirm that Sco X-1 shows a bimodal distribution of optical "high" and "low" states and rapid transitions between them on timescales less than 3 hours (or 0.15 orbits). We also find evidence that this behaviour has a typical systemic timescale of 4.8 days, which we interpret as a possible disc precession period in the system. Finally, we confirm the complex optical vs. X-ray correlation/anticorrelation behaviour for "high" and "low" optical states respectively.