Light curve morphology study of UW CrB – evidence for a 5 d superorbital period |
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| Authors: | Pasi Hakala Linnea Hjalmarsdotter Diana C Hannikainen Panu Muhli † |
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| Institution: | Tuorla Observatory, Väisäläntie 20, University Of Turku, FIN-21500 Piikkiö, Finland;Observatory, PO BOX 14, University of Helsinki, FIN-00014, Finland;Metsähovi Radio Observatory/TKK, Metsähovintie 114, FIN-02540 Kylmälä, Finland |
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| Abstract: | Since its discovery in 1990, UW CrB (also known as MS1603+2600) has remained a peculiar source without firm classification. Our current understanding is that it is an accretion disc corona (ADC) low-mass X-ray binary. In this paper, we present results from our photometric campaign dedicated to studying the changing morphology of the optical light curves. We find that the optical light curves show remarkable evidence for strongly evolving light curve shapes. In addition, we find that these changes show a modulation at a period of ～5 d. We interpret these changes as either due to strong periodic accretion disc warping or due to other geometrical changes because of disc precession at a period of 5 d. Finally, we have detected 11 new optical bursts, the phase distribution of which supports the idea of a vertically extended asymmetric accretion disc. |
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| Keywords: | accretion accretion discs binaries: close |
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