| Description |
We propose to obtain the broad-band medium-resolution spectra of 15 known outbursting sources with Herschel PACS and SPIRE to cover the 50-650 micron range and to study both the continuum (and the spectral features of ices and dust) and the emission lines. Additional photometry with PACS and SPIRE will be obtained to better characterize the direct environment of the FU Orionis objects. The main goals are 1) to place the FU Ori objects in the context of young stellar evolution by looking for differences in infrared spectral diagnostics between FU Ori objects and regular young stars. To this end we plan 2) to study the composition and evolution of dust grains in FU Ori objects, 3) to look for the presence of ices, 4) to identify atomic lines, in particular faint lines not previously or barely identified with ISO and to use line ratios to constrain the emission mechanism, 5) to search for molecular lines of hydroxyl and water, and of high transition states of (J=13-30) of CO. The CO lines will be used to constrain the origin of the lines (outflow, disk), 6) to use the Herschel spectra and photometry with ground-based and Spitzer data to fit the spectral energy distributions with radiative transfer codes to derive the disk and envelope properties. The Herschel observations of our sample of outbursting sources will probe an important phase in the life of young stellar objects with the aim to better understand their differences and their common properties, and to better place them into the evolutionary sequence from Class I star to Class II stars. |
