http://arxiv.org/abs/1906.03522
OMC-2/3 is one of the nearest embedded cluster-forming region that includes intermediate-mass protostars at early stages of evolution. A previous CO (3–2) mapping survey towards this region revealed outflow activity related to sources at different evolutionary phases. The present work aims to study the warm gas in the high-velocity emission from several outflows found in CO (3–2) emission by previous observations, determine their physical conditions, and make comparison with previous results in low-mass star-forming regions. We use the CHAMP+ heterodyne array on the APEX telescope to map the CO (6–5) and CO (7–6) emission in the OMC-2 FIR 6 and OMC-3 MMS 1-6 regions, and to observe $^{13}$CO (6–5) at selected positions. We analyze these data together with previous CO (3–2) observations. In addition, we mapped the SiO (5–4) emission in OMC-2 FIR 6. The CO (6–5) emission was detected in most of the outflow lobes in the mapped regions, while the CO (7–6) was found mostly from the OMC-3 outflows. In the OMC-3 MMS 5 outflow, a previously undetected extremely high velocity gas was found in CO (6–5). This extremely high velocity emission arises from the regions close to the central object MMS 5. Radiative transfer models revealed that the high-velocity gas from MMS 5 outflow consists of gas with $n_{\rm H_2}=$10$^4$–10$^{5}$ cm$^{-3}$ and $T>$ 200 K, similar to what is observed in young Class 0 low-mass protostars. For the other outflows, values of $n_{\rm H_2}>$10$^{4}$ cm$^{-3}$ were found. The physical conditions and kinematic properties of the young intermediate-mass outflows presented here are similar to those found in outflows from Class 0 low-mass objects. Due to their excitation requirements, mid$-J$ CO lines are good tracers of extremely high velocity gas in young outflows likely related to jets.
A. Gómez-Ruiz, A. Gusdorf, S. Leurini, et. al.
Tue, 11 Jun 19
25/60
Comments: Accepted for publication in Astronomy & Astrophysics
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