CALYPSO view of SVS 13A with PdBI: Multiple jet sources

¹ Institut de Radioastronomie Millimétrique (IRAM), 300 rue de la Piscine, 38406 Saint-Martin d’Hères, France
e-mail: lefevre@iram.fr
² LERMA, Observatoire de Paris, CNRS, 61 Av. de l’Observatoire, 75014 Paris, France
³ Laboratoire AIM-Paris-Saclay, CEA/DSM/Irfu – CNRS – Université Paris Diderot, CE-Saclay, 91191 Gif-sur-Yvette, France
⁴ Osservatorio Astrofisico di Arcetri, Largo Enrico Fermi 5, 50125 Florence, Italy
⁵ Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany
⁶ Univ. Grenoble Alpes, CNRS, IPAG, 38000 Grenoble, France

Received: 10 March 2017
Accepted: 6 July 2017

Abstract

Aims. We aim to clarify the origin of the multiple jet features emanating from the binary protostar SVS 13A (=VLA4A/VLA4B).

Methods. We used the Plateau de Bure Interferometer to map at 0.3–0.8′′ (~70–190 au) dust emission at 1.4 mm, CO(2–1), SiO(5–4), SO(6₅–5₄). Revised proper motions for VLA4A/4B and jet wiggling models are computed to clarify their respective contribution.

Results. VLA4A shows compact dust emission suggestive of a disk <50 au, and is the hot corino source, while CO/SiO/SO counterparts to the small-scale H₂ jet originate from VLA4B and reveal the jet variable velocity structure. This jet exhibits ≃ 3″ wiggling consistent with orbital motion around a yet undetected ≃20–30 au companion to VLA4B, or jet precession. Jet wiggling combined with velocity variability can explain the large apparent angular momentum in CO bullets. We also uncover a synchronicity between CO jet bullets and knots in the HH7–11 chain demonstrating that they trace two distinct jets. Their ≃300 yr twin outburst period may be triggered by close perihelion approach of VLA4A in an eccentric orbit around VLA4B. A third jet is tentatively seen at PA ≃ 0°.

Conclusions. SVS13 A harbors at least 2 and possibly 3 distinct jet sources. The CO and HH7-11 jets are launched from quasi-coplanar disks, separated by 20–70 au. Their synchronous major events every 300 yr favor external triggering by close binary interactions, a scenario also invoked for FU Or outbursts.