The deep eclipses of RW Aur revisited by long-term photometric and spectroscopic monitoring

Abstract

RW Aurigae is a young stellar system containing a classical T Tauri star as the primary component. It shows deep, irregular dimmings, first detected in 2010. At the University Observatory Jena, we carried out optical follow-up observations. We performed multiband (BVRI) photometry of the system with the Cassegrain-Teleskop-Kamera II and the Schmidt-Teleskop-Kamera between September 2016 and April 2019, as well as spectroscopy, using the Fibre Linked ÉCHelle Astronomical Spectrograph between September 2016 and April 2018. We present the apparent photometry of RW Aur, which is consistent with and complementary to photometric data from the American Association of Variable Star Observers. The V-band magnitude of RW Aur changed by up to three magnitudes during the timespan of our monitoring campaign. For the observing epochs 2016/2017 and 2017/2018 we report a decreasing brightness, while in the epoch 2018/2019 the system remained in a relatively constant bright state. In the color-magnitude diagram, we see that RW Aur lies close to a track for grey extinction. The spectra show a decreasing equivalent width (EW) of the $H\alpha$ emission line for decreasing brightness, whereas the EW of the $\left[OI\right]$ line increases, indicating an increased outflow activity during the obscuration. Both give further evidence for the favored theory that the obscurations are caused by a hot dusty wind emerging from the inner disk.