Re-brightening of the young star RW Aur: the end of the second deep eclipse
ATel #9428; Aleks Scholz, Inna Bozhinova (University of St Andrews, UK), Oliver Lux, Anna Pannicke, Markus Mugrauer (Astronomical Institute and University Observatory Jena, Germany)
on 30 Aug 2016; 07:59 UT
Credential Certification: Aleks Scholz (as110@st-andrews.ac.uk)
Subjects: Optical, Young Stellar Object
The young star RW Aur (05 07 49.6, +30 24 05.2) has been in eclipse for the last two years. From spring 2015 onwards, the star has been measured at R-band magnitudes between 11.9 and 12.6, more than 2 magnitudes fainter than normal, as we report in a forthcoming paper (Bozhinova et al., MNRAS, under review). On March 31 2016, our last epoch before RW Aur became unobservable, we report an R-band magnitude of 12.4. This eclipse is the second extreme obscuration event in RW Aur, after an eclipse in 2010-11, and of unprecedented depth and duration for this star which has been observed for more than a century. The origin of these events is debated in the literature (see Rodriguez et al. 2016, AJ, 151, 29; Schneider et al. 2015, A&A, 584, 9; Petrov et al., 2015, A&A, 577, 73).
We have now secured new observations with the 25cm telescope at the University Observatory Jena in Großschwabhausen, which show that the 2014-16 eclipse has come to an end. From images taken on Aug 25 (1:35UT) and Aug 26 (2:23UT) with the CTK-II (Cassegrain-Teleskop-Kamera II, a 1Kx1K E2V CCD) we measure approximate R-band magnitudes of 10.7 and 10.6 (error 0.1 mag). This was derived by comparing with the photometry of 3 nearby stars which have R-band magnitudes in the USNO-B1.0 catalogue. The airmass for these observations was 1.7 and 1.4, respectively. The re-brightening of RW Aur is confirmed by the most recent observations reported by AAVSO (https://www.aavso.org/), with visual magnitudes between 11 and 10.5. RW Aur is still slightly fainter than the typical out-of-eclipse level (e.g., R=10.09 in the USNO-B1.0 catalogue). Multi-color photometry and spectroscopy are encouraged to track the end of this two-year long event.
