An analysis of the environments of FU orionis objects with Herschel

We present Herschel-HIFI, SPIRE, and PACS 50-670 µm imaging and spectroscopy of six FU Orionis-type objects and candidates (FU Orionis, V1735 Cyg, V1515 Cyg, V1057 Cyg, V1331 Cyg, and HBC 722), ranging in outburst date from 1936-2010, from the “FOOSH” (FU Orionis Objects Surveyed with Herschel) program, as well as ancillary results from Spitzer-IRS and the Caltech Submillimeter Observatory. In their system properties (Lbol, Tbol, line emission), we find that FUors are in a variety of evolutionary states. Additionally, some FUors have features of both Class I and II sources: warm continuum consistent with Class II sources, but rotational line emission typical of Class I, far higher than Class II sources of similar mass/luminosity. Combining several classification techniques, we find an evolutionary sequence consistent with previous mid-IR indicators. We detect [O I] in every source at luminosities consistent with Class 0/I protostars, much greater than in Class II disks. We detect transitions of 13 CO (Jup of 5 to 8) around two sources (V1735 Cyg and HBC 722) but attribute them to nearby protostars. Of the remaining sources, three (FU Ori, V1515 Cyg, and V1331 Cyg) exhibit only low-lying CO, but one (V1057 Cyg) shows CO up to J = 23 ! 22 and evidence for H2O and OH emission, at strengths typical of protostars rather than T Tauri stars. Rotational temperatures for “cool” CO components range from 20-81 K, for � 10 50 total CO molecules. We detect [C I] and [N II] primarily as diffuse emission. Subject headings: stars: pre-main sequence — stars: variables: T Tauri — ISM: jets and outflows — submillimeter: ISM — stars: individual (HBC 722, FU Orionis, V1057 Cyg, V1735 Cyg, V1331 Cyg, V1515 Cyg)