Astronomy and Astrophysics, volume 642A, 216-216 (2020/10-1)
Probing the hidden atomic gas in Class I jets with SOFIA.
SPERLING T., EISLOFFEL J., FISCHER C., NISINI B., GIANNINI T. and KRABBE A.
Abstract (from CDS):
Context. We present SOFIA/FIFI-LS observations of five prototypical, low-mass Class I outflows (HH111, SVS13, HH26, HH34, HH30) in the far-infrared [OI]63µm and [OI]145µm transitions.
Aims. Spectroscopic [OI]63µm,145µm maps enable us to study the spatial extent of warm, low-excitation atomic gas within outflows driven by Class I protostars. These [OI] maps may potentially allow us to measure the mass-loss rates (Mjet) of this warm component of the atomic jet.
Methods. A fundamental tracer of warm (i.e. T∼500-1500K), low-excitation atomic gas is the [OI]63µm emission line, which is predicted to be the main coolant of dense dissociative J-type shocks caused by decelerated wind or jet shocks associated with protostellar outflows. Under these conditions, the [OI]63µm line can be directly connected to the instantaneous mass ejection rate. Thus, by utilising spectroscopic [OI]63µm maps, we wish to determine the atomic mass flux rate Mjet ejected from our target outflows.
Results. Strong [OI]63µm emission is detected at the driving sources HH111IRS, HH34IRS, SVS13, as well as at the bow shock region, HH7. The detection of the [OI]63µm line at HH26A and HH8/HH10 can be attributed to jet deflection regions. The far-infrared counterpart of the optical jet is detected in [OI]63µm only for HH111, but not for HH34. We interpret the [OI]63µm emission at HH111IRS, HH34IRS, and SVS13 to be coming primarily from a decelerated wind shock, whereas multiple internal shocks within the HH111 jet may cause most of the [OI]63µm emission seen there. At HH30, no [OI]63µm,145µm was detected. The [OI]145µm line detection is at noise level almost everywhere in our obtained maps. The observed outflow rates of our Class I sample are to the order of Mjet∼10–6M☉/yr, if proper shock conditions prevail. Independent calculations connecting the [OI]63µm line luminosity and observable jet parameters with the mass -loss rate are consistent with the applied shock model and lead to similar mass-loss rates. We discuss applicability and caveats of both methods.
Conclusions. High-quality spectroscopic [OI]63µm maps of protostellar outflows at the jet driving source potentially allow a clear determination of the mass ejection rate.
© ESO 2020
stars: formation - stars: mass-loss - ISM: jets and outflows - Herbig-Haro objects
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<Available at CDS (J/A+A/642/A216): table1.dat table2.dat list.dat fits/*>
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