Program: GN-2013B-Q-47

Eruptive pre-main sequence (PMS) variable stars suffer episodic outbursts, which can persist from months to ~100 yr, due to an abrupt increase in the accretion rate onto the central stars by a factor of up to 1000. The original classification divides this group into two distinctive subclasses with long bursts (FUors) or short bursts (EXors), which are spectroscopically distinct. This optically-based scheme struggles to include intermediate objects and tends to exclude even younger, optically invisible protostars. Only a small number of eruptive PMS variables are known but the phenomenon is thought to be a common part of PMS evolution. If so, this may resolve some long-standing problems in star formation. To quantify this phenomenon we are conducting a search for eruptive variables in the UKIDSS Galactic Plane Survey. Spectroscopic follow up with NIFS in 2012B has confirmed the eruptive variable nature of at least four stars. They show a mix of characteristics, with two objects in the protostar subclass (adding to only 3 previously known). We propose NIFS spectroscopy of new candidates from the recent GPS DR8 release as part of an ongoing effort to characterize eruptive variability and quantify its incidence by expanding the size of the sample, particularly the subclass of optically invisible protostars.