Evidence for episodic warm outflowing CO gas from the intermediate-mass young stellar object IRAS 08470–4321

We present a R ≃ 10 000 M-band spectrum of LLN 19 (IRAS 08470−4321), a heavily embedded intermediate-mass young stellar object located in theVela molecular cloud, obtained with the Very Large Telescope (VLT)-Infrared Spectrometer And Array Camera (ISAAC). The data were fitted by a two-slab cold-hot model and a wind model. The spectrum exhibits deep broad ro-vibrational absorption lines of ^(12)CO v = 1←0 and ^(13)CO v = 1←0. A weak CO ice feature at 4.67 μmis also detected. Differences in velocity indicate that the warm gas is distinct from the cold millimetre emitting gas, which may be associated with the absorption by cooler gas (45 K). The outflowing warm gas at 300–400 K and with a mass-loss rate varying between 0.48 × 10^(−7) and 4.2 × 10^(−7) M_⊙ yr^(−1) can explain most of the absorption. Several absorption lines were spectrally resolved in subsequent spectra obtained with the VLT-Cryogenic Infrared Echelle Spectrograph (CRIRES) instrument. Multiple absorption substructures in the highresolution (R = 100 000) spectra indicate that the mass-loss is episodic with at least two major events that occurred recently (