Poster Abstracts

Name/Affiliation:  Phil Lucas (University of Hertfordshire)

Title:  Eruptive variable protostars: the view from VISTA and UKIDSS

Until now the Milky Way has been largely unexplored territory in the time domain, especially in the infrared. A consequence of this is that it has not been possible to address the longstanding question of whether FUor/EXor type unsteady accretion is common amongst Young Stellar Objects (YSOs), with all the implications that would have for masses and ages of normal pre-main sequence stars. We present a sample of ~800 high amplitude (DeltaK>1 mag) infrared variable stars from VVV (Vista Variables in the Via Lactea), a large ESO time domain public survey with the VISTA telescope. This sample is complemented by a further ~200 high amplitude variables from the UKIDSS Galactic plane survey. We show that most of these objects are YSOs, usually too obscured by extinction to be detectable in the optical. High quality spectra from Magellan/FIRE and Gemini/NIFS indicate that many of these objects are eruptive variables, although other populations are present. The SEDs indicate that we are seeing objects at an earlier stage in their evolution than most classical FUors and EXors, corresponding to a time when the average accretion rate was somewhat higher. In the course of this project we expect to be able to quantify the incidence of eruptive variability on timescales up to a few years. It is also reasonable to hope that new types of stellar variable will be discovered.