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Information Bulletin on Variable Stars


EX Lup is the prototype of EXors, a class of pre-main sequence eruptive variables, exhibiting unpredictable brightenings lasting some months (Herbig, 1977; Herbig et al., 2001; Herbig, 2007). According to the current picture, eruptions of pre-main sequence stars are caused by enhanced accretion (Hartmann & Kenyon, 1996). In quiescent phase, EX Lup has typically V 13 mag, while in outburst, it may brighten by 1{4 mag. The last known are-up happened in 2002 (Herbig, 2007). As was announced by Jones (2008), EX Lup has been in outburst again since at least 2008 January 15. Based on visual estimates, the star reached a peak brightness of 8 mag, brighter than at any time before. We started an optical spectroscopic monitoring programme on 2008 January 25. In this paper we present our spectra collected until 2008 February 17, as well as the visual light curve for the same period.

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