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Dark spot, Spiral waves and the SW Sex behaviour: it is all about UX Ursae Majoris

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dc.contributor.author Shearer, Andrew en
dc.date.accessioned 2011-03-10T16:58:18Z en
dc.date.available 2011-03-10T16:58:18Z en
dc.date.issued 2010 en
dc.identifier.citation V. V. Neustroev, V. F. Suleimanov, N. V. Borisov, K. V. Belyakov, A. Shearer...(2010)Dark spot, Spiral waves and the SW Sex behaviour: it is all about UX Ursae Majoris, en
dc.identifier.uri http://hdl.handle.net/10379/1734 en
dc.description.abstract We present an analysis of time-resolved, medium resolution optical spectroscopic observations of UX UMa in the blue (3920-5250 A) and red (6100-7200 A) wavelength ranges, that were obtained in April 1999 and March 2008 respectively. The observed characteristics of our spectra indicate that UX UMa has been in different states during those observations. The blue spectra are very complex. They are dominated by strong and broad single-peaked emission lines of hydrogen. The high-excitation lines of HeII 4686 and the Bowen blend are quite strong as well. All the lines consist of a mixture of absorption and emission components. Using Doppler tomography we have identified four distinct components of the system: the accretion disc, the secondary star, the bright spot from the gas stream/disc impact region, and the unique compact area of absorption in the accretion disc seen as a dark spot in the lower-left quadrant of the tomograms. In the red wavelength range, both the hydrogen (H_alpha) and neutral helium (HeI 6678 and HeI 7065) lines were observed in emission and both exhibited double-peaked profiles. Doppler tomography of these lines reveals spiral structure in the accretion disc, but in contrast to the blue wavelength range, there is no evidence for either the dark spot or the gas stream/disc impact region emission, while the emission from the secondary star is weak. During the observations in 1999, UX UMa showed many of the defining properties of the SW Sex stars. However, all these features almost completely disappeared in 2008. We have also estimated the radial velocity semi-amplitudes K_1 and K_2 and evaluated the system parameters of UX UMa. These estimates are inconsistent with previous values derived by means of analysis of WD eclipse features in the light curve in the different wavelength ranges. en
dc.format application/pdf en
dc.language.iso en en
dc.subject Astrophysics - Solar and Stellar Astrophysics en
dc.title Dark spot, Spiral waves and the SW Sex behaviour: it is all about UX Ursae Majoris en
dc.type Article en
dc.local.publishedsource http://arxiv.org/pdf/1006.3106 en
dc.description.peer-reviewed peer-reviewed en
dc.local.authors V. V. Neustroev, V. F. Suleimanov, N. V. Borisov, K. V. Belyakov, A. Shearer en
dc.local.arxivid 1006.3106 en

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