Volume 629, September 2019
|Number of page(s)||11|
|Section||Interstellar and circumstellar matter|
|Published online||10 September 2019|
Warm gas in protostellar outflows
II. Extremely high-velocity emission jet and outflows from OMC-2/3★
CONACYT–Instituto Nacional de Astrofísica, Óptica y Electrónica,
Luis E. Erro 1,
2 LERMA, UMR 8112 du CNRS, Observatoire de Paris, École Normale Supérieure, 61 Av. de l’Observatoire, 75014 Paris, France
3 INAF – Osservatorio Astronomico di Cagliari, Via della Scienza 5, 09047 Selargius (CA), Italy
4 Max-Planck-Institut für Radioastronomie (MPIfR), Auf dem Hügel 69, 53121 Bonn, Germany
5 Joint ALMA Observatory, Alonso de Córdova 3107, Vitacura, Santiago, Chile
6 NAOJ Chile Observatory, Alonso de Córdova 3788, Oficina 61B, Vitacura, Santiago, Chile
7 Department of Astronomical Science, School of Physical Sciences, SOKENDAI (The Graduate University for Advanced Studies), Mitaka, Tokyo 181-8588, Japan
Accepted: 7 June 2019
Context. OMC-2/3 is one of the nearest embedded cluster-forming regions 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.
Aims. The present work presents a study of the warm gas in the high-velocity emission from several outflows found in CO (3–2) emission by previous observations, determines their physical conditions, and makes a comparison with previous results in low-mass star-forming regions.
Methods. We used 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 13CO (6–5) at selected positions. We analyzed these data together with previous CO (3–2) observations. In addition, we mapped the SiO (5–4) emission in OMC-2 FIR 6.
Results. 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 in 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 nH2 = 104–105 cm−3 and T > 200 K, similar to what is observed in young Class 0 low-mass protostars. For the other outflows, values of nH2 > 104 cm−3 were found.
Conclusions. 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.
Key words: stars: formation / ISM: clouds / ISM: jets and outflows / shock waves / ISM: individual objects: OMC-2/3
© ESO 2019
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