Adolfo Carvalho (Caltech): "The Most Extreme Young Stellar Accretion Outbursts"

FU Ori objects are a class of rapidly accreting young stellar objects (YSOs) that have undergone a 4-5 magnitude outburst in the visible band. During outbursts, the accretion rates of the Class I/II YSO progenitors jump from 1e-08 to 1e-05 or 1e-4 solar masses per year. The accretion episodes are believed to last around 100 years, but exactly what mechanism triggers the burst and is able to maintain such a high accretion rate is not known. Persistent follow-up of two recent FU Ori outbursts, V960 Mon and HBC 722, spanning 10+ years of high- and low-resolution spectroscopy and photometry enables us to study them in detail. I will discuss the characteristics of the individual components that we can observe in these two YSO accretion disk systems and how they evolve in time. I will also highlight the differences between the two systems and how they may imply different outburst mechanisms.