PP 13S, a young, low-mass FU Orionis-type pre-main sequence star

We present near-IR imaging and spectroscopy, together with sub-mm/mm photometry and 12CO molecular line maps of the cometary nebula PP 13S. Previous models have been unable to resolve whether PP 13S is a young, pre-main sequence star or an old, evolved object. Our new observations prove conclusively that PP 13S is a young stellar object with a luminosity of ∼30 L and an accretion disk with an inclination of ∼ 40◦. It has a 12CO J=2–1 outflow, strong and broadened CO overtone band absorption, and vibrationally excited H2 emission. We conclude that PP 13S has all the characteristics of an FU Orionis-type star, and although no outburst has been observed, we suggest that PP 13S should be added to the list of FUor premain sequence stars. Our study also includes PP13N, which we resolve into a young double star system.