EPoS Contribution
EPoS Contribution
Extreme Variables in Star Forming Regions

Carlos Contreras
Centre for Astrophysics Research (CAR), University of Hertfordshire, Hatfield, UnitedKingdom
FU Ori/EX Ori stars (FUORs/EXORs) are a class of low-mass Young Stellar Objects (YSOs) that show sudden and large increases in brightness believed to be caused by a steep increase in the mass being accreted onto the central star, going from 10^-7 Msun yr^-1 to 10^-4 Msun yr^-1. It is thought that these episodic outbursts may be common among pre-main sequence (PMS) stars. If so, it would help to explain many long standing problems in star formation. The aim of this project is to search for this kind of high-amplitude variables in the variability data of infrared surveys: UKIDSS Galactic Plane Survey (GPS) and the Vista Variables in the Via Lactea (VVV), and to determine how common are these episodic outbursts among PMS stars. Here, I present the results of the photometric and spectroscopic analysis of FUOR/EXOR candidates selected from the first tranche of the UKIDSS GPS variability data in DR5. Most of the candidates are in the Serpens OB2 association. Our analysis shows the discovery of two deeply embedded FUORs and 2 likely EXORs. Moreover, examination of the candidates in UKIDSS DR7 shows another concentration of high amplitude infrared variables in the Cygnus X region
Phil Lucas, CAR UH, England