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FAUST. II. Discovery of a Secondary Outflow in IRAS 15398-3359: Variability in Outflow Direction during the Earliest Stage of Star Formation?

Okoda, Y; Oya, Y; Francis, L; Johnstone, D; Inutsuka, S-I; Ceccarelli, C; Codella, C; ... Yamamoto, S; + view all (2021) FAUST. II. Discovery of a Secondary Outflow in IRAS 15398-3359: Variability in Outflow Direction during the Earliest Stage of Star Formation? The Astrophysical Journal , 910 , Article 11. 10.3847/1538-4357/abddb1. Green open access

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Abstract

We have observed the very low-mass Class 0 protostar IRAS 15398−3359 at scales ranging from 50 to 1800 au, as part of the Atacama Large Millimeter/Submillimeter Array Large Program FAUST. We uncover a linear feature, visible in H_{2}CO, SO, and C^{18}O line emission, which extends from the source in a direction almost perpendicular to the known active outflow. Molecular line emission from H_{2}CO, SO, SiO, and CH_{3}OH further reveals an arc-like structure connected to the outer end of the linear feature and separated from the protostar, IRAS 15398−3359, by 1200 au. The arc-like structure is blueshifted with respect to the systemic velocity. A velocity gradient of 1.2 km s^{−1} over 1200 au along the linear feature seen in the H_{2}CO emission connects the protostar and the arc-like structure kinematically. SO, SiO, and CH_{3}OH are known to trace shocks, and we interpret the arc-like structure as a relic shock region produced by an outflow previously launched by IRAS 15398−3359. The velocity gradient along the linear structure can be explained as relic outflow motion. The origins of the newly observed arc-like structure and extended linear feature are discussed in relation to turbulent motions within the protostellar core and episodic accretion events during the earliest stage of protostellar evolution.

Type: Article
Title: FAUST. II. Discovery of a Secondary Outflow in IRAS 15398-3359: Variability in Outflow Direction during the Earliest Stage of Star Formation?
Open access status: An open access version is available from UCL Discovery
DOI: 10.3847/1538-4357/abddb1
Publisher version: https://doi.org/10.3847/1538-4357/abddb1
Language: English
Additional information: This version is the version of record. For information on re-use, please refer to the publisher's terms and conditions.
UCL classification: UCL
UCL > Provost and Vice Provost Offices > UCL BEAMS
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
URI: https://discovery.ucl.ac.uk/id/eprint/10125865
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