Padova-Asiago Supernova Group
Outburst from Young Stellar Objects (YSO)
Large brightness changes in very young stars and protostars; Hartmann et al. 2016, ARA&A, 54, 125) can be related to different processes, including star to disk mass transfer, interactions between a star and an eccentric planet, disk instabilities, stellar shell releases and formation of an excretion disc. All of this can generates heterogeneous variability displays (e.g. FUor or EXor events produce decades- to months-long outbursts, respectively), or even puzzling events like like ASASSN-13db (Holoien et al. 2014, ApJL, 785, L23) and ASASSN-15qi (Herczeg et al. 2016, ApJ, 831, 133). An example of the light curve of the YSO ASASSN-13db is shown in Fig. 2 (ASASSN-13db, Sicilia-Aguilar et al. 2017).
Mid-IR composite image of the location of the YSO candidate ASASSN-15qi. Credits: Herczeg et al. 2016.
Fig 2 Long-term V-band light curve of ASASSN-13db. Credits: Figure from Sicilia-Aguilar et al. 2017 (preprint arXiv:1708.02010).