Investigation of Class I jets with SOFIA

Protostellar outflows in form of highly collimated jets or less collimated winds are spectacular phenomena associated with star formation (Bally 2016; Frank et al. 2014). Through them excess angular momentum is transported away from the young forming star during its main accretion phase. Outflows are proficient laboratories to study the ejection mechanism that plays a crucial role in many astrophysical objects (e.g. active galactic nuclei [AGNs], pulsars, Gamma-Ray Bursts). In this study nine protostellar outflows (Cep E, HH 1, HH 212, HH 26, HH 34, HH 111, L1551 IRS5, SVS 13, HH 30) have been mapped for the first time in both far-infrared transitions of atomic oxygen at 63.18 m and 145.53 m using the flying observatory SOFIA. These [O I]63,145 maps enable us to trace the warm (T 5005 000 K), neutral, and dense gas component of the outflow. The [O I]63 emission line is predicted to be the main coolant in a dissociative J-shock (Hollenbach and McKee 1989). Potentially, mass-loss rates can be determined from the [O I]63 line luminosity. Thus, the efficiency, that is the ratio between the mass-loss in the outflow and the mass accretion onto the source, can be estimated and compared with theoretical model predictions. Nisini et al. (2015) have already mapped five protostellar outflows from mainly Class 0 sources in [O I]63,145 with Herschel/PACS. Podio et al. (2012) could resolve the [O I]63 emission line towards four more evolved Class II outflows. In this context, our new SOFIA observations of mainly Class 0 and Class I outflow sources help to evaluate the evolutionary role of the neutral outflow component traced by [O I]63.


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