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Multi-scale view of star formation in IRAS 21078+5211: From clump fragmentation to disk wind

Moscadelli, L, Beuther, H, Ahmadi, A, Gieser, C, Massi, F, Cesaroni, R, Sánchez-Monge, Á, Bacciotti, F, Beltrán, MT, Csengeri, T, Galván-Madrid, R, Henning, T, Klaassen, PD, Kuiper, R, Leurini, S, Longmore, SN, Maud, LT, Möller, T, Palau, A, Peters, T , Pudritz, RE, Sanna, A, Semenov, D, Urquhart, JS, Winters, JM and Zinnecker, H Multi-scale view of star formation in IRAS 21078+5211: From clump fragmentation to disk wind. Astronomy and Astrophysics. ISSN 0004-6361 (Accepted)

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Abstract

In the massive star-forming region IRAS 21078+5211, a highly fragmented cluster (0.1~pc in size) of molecular cores is observed, located at the density peak of an elongated (1~pc in size) molecular cloud. A small (1~km/s per 0.1~pc) LSR velocity (Vlsr) gradient is detected across the axis of the molecular cloud. Assuming we are observing a mass flow from the harboring cloud to the cluster, we derive a mass infall rate of about 10^{-4}~M_{sun}~yr^{-1}. The most massive cores (labeled 1, 2, and 3) are found at the center of the cluster, and these are the only ones that present a signature of protostellar activity in terms of emission from high-excitation molecular lines or a molecular outflow. We reveal an extended (size about 0.1~pc), bipolar collimated molecular outflow emerging from core 1. We believe this is powered by a (previously discovered) compact (size <= 1000~au) radio jet, ejected by a YSO embedded in core 1 (named YSO-1), since the molecular outflow and the radio jet are almost parallel and have a comparable momentum rate. By means of high-excitation lines, we find a large (14~km/s over 500~au) Vlsr gradient at the position of YSO-1, oriented approximately perpendicular to the radio jet. Assuming this is an edge-on, rotating disk and fitting a Keplerian rotation pattern, we determine the YSO-1 mass to be 5.6+/-2.0~M_{sun}. The water masers (previously observed with VLBI) emerge within 100-300~au from YSO-1 and are unique tracers of the jet kinematics. Their three-dimensional (3D) velocity pattern reveals that the gas flows along, and rotates about, the jet axis. We show that the 3D maser velocities are fully consistent with the magneto-centrifugal disk-wind models predicting a cylindrical rotating jet. Under this hypothesis, we determine the jet radius to be about 16~au and the corresponding launching radius and terminal velocity to be about 2.2~au and 200~km/s, respectively.

Item Type: Article
Uncontrolled Keywords: astro-ph.GA; astro-ph.GA; astro-ph.SR
Subjects: Q Science > QB Astronomy
Q Science > QC Physics
Divisions: Astrophysics Research Institute
Publisher: EDP Sciences
Related URLs:
Date Deposited: 15 Feb 2021 12:19
Last Modified: 15 Feb 2021 12:30
URI: https://researchonline.ljmu.ac.uk/id/eprint/14461

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