Herschel/PACS far-IR spectral imaging of a jet from an intermediate mass protostar in the OMC-2 region

Abstract

We present the first detection of a jet in the far-IR [O I] lines from an intermediate mass protostar. We have carried out a Herschel/PACS spectral mapping study in the [O I] lines of OMC-2 FIR 3 and FIR 4, two of the most luminous protostars in Orion outside of the Orion Nebula. The spatial morphology of the fine structure line emission reveals the presence of an extended photodissociation region (PDR) and a narrow, but intense jet connecting the two protostars. The jet seen in [O I] emission is spatially aligned with the Spitzer/IRAC 4.5 µm jet and the CO (6-5) molecular outflow centered on FIR 3. The mass loss rate derived from the total [O I] 63 µm line luminosity of the jet is 7.7 ×10 −6 M yr −1 , more than an order of magnitude higher than that measured for typical low mass class 0 protostars. The implied accretion luminosity is significantly higher than the observed bolometric luminosity of FIR 4, indicating that the [O I] jet is unlikely to be associated with FIR 4. We argue that the peak line emission seen toward FIR 4 originates in the terminal shock produced by the jet driven by FIR 3. The higher mass-loss rate that we find for FIR 3 is consistent with the idea that intermediate mass protostars drive more powerful jets than their low-mass counterparts. Our results also call into question the nature of FIR 4.

The VLA/ALMA Nascent Disk and Multiplicity (VANDAM) Survey of Orion Protostars. I. Identifying and Characterizing the Protostellar Content of the OMC-2 FIR4 and OMC-2 FIR3 Regions

“…It is difficult, however, to reconcile the appearance of the loops surrounding HOPS-108 with a typical bi-polar outflow. Also, the 12 CO emission in the vicinity of HOPS-108 could be complex due to the outflow from HOPS-370 (FIR3) crossing this region (Shimajiri et al 2008;González-García et al 2016a). Other searches for outflows in Orion from 13 CO emission (Williams et al 2003), 12 CO (Shimajiri et al 2008;Hull et al 2014;Kong et al 2018), and the near-infrared (Davis et al 2009;Stanke et al 2006) are also not conclusive for HOPS-108.…”

Star Formation Under the Outflow: The Discovery of a Non-thermal Jet from OMC-2 FIR 3 and Its Relationship to the Deeply Embedded FIR 4 Protostar

“…These results are consistent with the VLA 12 knots being part of a non-thermal radio jet either originating from the Class 0 protostar HOPS 108 (FIR 4), which falls in between the VLA 12C and the VLA 12S knots, or from the intermediate-mass Class I YSO HOPS 370 (FIR 3), as the VLA 12 knots are roughly aligned in the direction of the VLA 11 radio jet associated with HOPS 370 (Figure 1) and fall on the southwest lobe of the outflow observed at submillimeter and far-IR wavelengths (Manoj et al 2013;González-García et al 2016) driven by this object.…”

“…It has been proposed that shocks associated with the interaction of jets with the surrounding medium could compress the gas and induce local instabilities that may trigger star formation (e.g., Yokogawa et al 2003;Graves et al 2010;Duarte-Cabral et al 2011). In particular, this scenario has been proposed for HOPS 108, as it is associated with strong shocks (Manoj et al 2013;González-García et al 2016) and is probably interacting with a nearby dense core (Shimajiri et al 2008). Interestingly, the shape of the jet in the region of the VLA 12 knots appears to follow the eastern edge of a clump of enhanced dust emission, as imaged by ALMA at 3 mm (Kainulainen et al 2017; see Figure 2, right panel).…”

“…Such a large velocity implies that it should have been acquired very recently (200 year) in order for the star to be formed in the proximity (within a few arcsec) of its current position, in the region where the shock emission has been identified (Manoj et al 2013;González-García et al 2016). Otherwise, if this velocity was maintained during a longer time interval, it would imply that the HOPS 108 protostar originated at a distant position from its current location, making the triggering hypothesis inviable.…”

The Herschel Orion Protostar Survey: Far-infrared Photometry and Colors of Protostars and Their Variations across Orion A and B*

“…This paper is part of a series describing results from HOPS. These papers include evolutionary studies of protostars via modeling of their SEDs (Furlan et al 2016;Fischer et al 2017), the analysis of far-IR protostellar spectra (Manoj et al 2013(Manoj et al , 2016, the discovery and characterization of the youngest protostars (Stutz et al 2013;Tobin et al 2015Tobin et al , 2016Karnath et al 2020), a study of multiplicity in the Orion YSOs (Kounkel et al 2016), progress on understanding outburst phenomena in protostars (Fischer et al 2012(Fischer et al , 2019Safron et al 2015), and detailed studies of the active OMC 2/3 region (Furlan et al 2014;González-García et al 2016;Osorio et al 2017).…”