Schutzer, A de A;
Rivera-Ortiz, PR;
Lefloch, B;
Gusdorf, A;
Favre, C;
Segura-Cox, D;
Lopez-Sepulcre, A;
... Witzel, A; + view all
(2022)
SOLIS XVI. Mass ejection and time variability in protostellar outflows: Cep E.
Astronomy & Astrophysics
, 662
, Article A104. 10.1051/0004-6361/202142931.
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Abstract
Context. Protostellar jets are an important agent of star formation feedback, tightly connected with the mass-accretion process. The history of jet formation and mass ejection provides constraints on the mass accretion history and on the nature of the driving source. Aims. We characterize the time-variability of the mass-ejection phenomena at work in the class 0 protostellar phase in order to better understand the dynamics of the outflowing gas and bring more constraints on the origin of the jet chemical composition and the mass-accretion history. Methods. Using the NOrthern Extended Millimeter Array (NOEMA) interferometer, we have observed the emission of the CO 2–1 and SO N_{J} = 5_{4}–4_{3} rotational transitions at an angular resolution of 1.0″ (820 au) and 0.4″ (330 au), respectively, toward the intermediate-mass class 0 protostellar system Cep E. Results. The CO high-velocity jet emission reveals a central component of ≤400 au diameter associated with high-velocity molecular knots that is also detected in SO, surrounded by a collimated layer of entrained gas. The gas layer appears to be accelerated along the main axis over a length scale δ_{0} ~ 700 au, while its diameter gradually increases up to several 1000 au at 2000 au from the protostar. The jet is fragmented into 18 knots of mass ~10^{−3} M⊙, unevenly distributed between the northern and southern lobes, with velocity variations up to 15 km s−1 close to the protostar. This is well below the jet terminal velocities in the northern (+ 65 km s^{−1}) and southern (−125 km s−1) lobes. The knot interval distribution is approximately bimodal on a timescale of ~50–80 yr, which is close to the jet-driving protostar Cep E-A and ~150–20 yr at larger distances >12″. The mass-loss rates derived from knot masses are steady overall, with values of 2.7 × 10^{−5} M⊙ yr^{−1} and 8.9 × 10^{−6} M⊙ yr^{−1} in the northern and southern lobe, respectively. Conclusions. The interaction of the ambient protostellar material with high-velocity knots drives the formation of a molecular layer around the jet. This accounts for the higher mass-loss rate in the northern lobe. The jet dynamics are well accounted for by a simple precession model with a period of 2000 yr and a mass-ejection period of 55 yr.
| Type: | Article |
|---|---|
| Title: | SOLIS XVI. Mass ejection and time variability in protostellar outflows: Cep E |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1051/0004-6361/202142931 |
| Publisher version: | https://doi.org/10.1051/0004-6361/202142931 |
| Language: | English |
| Additional information: | © The European Southern Observatory (ESO). Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0). |
| Keywords: | ISM: jets and outflows, ISM: kinematics and dynamics, stars: formation |
| UCL classification: | UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Physics and Astronomy UCL > Provost and Vice Provost Offices > UCL BEAMS UCL |
| URI: | https://discovery-pp.ucl.ac.uk/id/eprint/10151996 |
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