Mass ejection and time variability in protostellar outflows: Cep E. SOLIS XVI

• Published in: arXiv.org 2022-03
• Main Authors: de A Schutzer, A, Rivera-Ortiz, P R, Lefloch, B, Gusdorf, A, Favre, C, Segura-Cox, D, Lopez-Sepulcre, A, Neri, R, Ospina-Zamudio, J, De Simone, M, Codella, C, Viti, S, Podio, L, Pineda, J, O'Donoghue, R, Ceccarelli, C, Caselli, P, Alves, F, Bachiller, R, Balucani, N, Bianchi, E, Bizzocchi, L, Bottinelli, S, Caux, E, Chacón-Tanarro, A, Dulieu, F, Enrique-Romero, J, Fontani, F, Feng, S, Holdship, J, Jiménez-Serra, I, A Jaber Al-Edhari, Kahane, C, Lattanzi, V, Oya, Y, Punanova, A, Rimola, A, Sakai, N, Spezzano, S, Sims, I R, Taquet, V, Testi, L, Theulé, P, Ugliengo, P, Vastel, C, Vasyunin, A I, Vazart, F, Yamamoto, S, Witzel, A
• Format: Article
• Language: English
• Subjects: Astrochemistry; Chemical composition; Deposition; Ejection; Emission; Knots; Protostars; Star & galaxy formation; Star formation; Sulfur dioxide; Velocity
• ISSN: 2331-8422
• DOI: 10.48550/arxiv.2203.09383

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 the nature of the driving source. We want to 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. We have observed the emission of the CO 2-1 and SO N_J=5_4-4_3 rotational transitions with NOEMA, towards the intermediate-mass Class 0 protostellar system Cep E. The CO high-velocity jet emission reveals a central component associated with high-velocity molecular knots, also detected in SO, surrounded by a collimated layer of entrained gas. The gas layer appears to accelerate along the main axis over a length scale delta_0 ~700 au, while its diameter gradually increases up to several 1000au at 2000au from the protostar. The jet is fragmented into 18 knots of mass ~10^-3 Msun, unevenly distributed between the northern and southern lobes, with velocity variations up to 15 km/s close to the protostar, well below the jet terminal velocities. The knot interval distribution is approximately bimodal with a scale of ~50-80yr close to the protostar and ~150-200yr at larger distances >12". The mass-loss rates derived from knot masses are overall steady, with values of 2.7x10^-5 Msun/yr (8.9x10^-6 Msun/yr) in the northern (southern) lobe. The interaction of the ambient protostellar material with high-velocity knots drives the formation of a molecular layer around the jet, which accounts for the higher mass-loss rate in the north. The jet dynamics are well accounted for by a simple precession model with a period of 2000yr and a mass-ejection period of 55yr.