A kinematical study of the launching region of the blueshifted HH 46/47 outflow with SINFONI K-band observations

TL;DR

This study uses high-resolution near-infrared observations to analyze the kinematics of the HH 46/47 outflow, revealing layered structures, velocity gradients, and asymmetries, contributing to understanding outflow dynamics and their impact on star formation.

Contribution

First detailed kinematic analysis of the HH 46/47 outflow base using VLT/SINFONI, highlighting layered structures and velocity gradients, and challenging the rotation interpretation.

Findings

Confirmed a 10 km/s transverse velocity gradient in the H2 outflow cavity.

Identified layered structure with high-velocity [Fe II] jet surrounded by H2 cavity.

Eliminated outflow rotation as the sole cause of observed velocity gradients.

Abstract

Studying outflows is important as they may significantly contribute to angular momentum removal from the star/disk system, affecting disk evolution and planet formation. To investigate the different outflow components; the collimated jet, wide-angled molecular outflow, and outflow cavity, of the Class I HH 46/47 outflow system. We focus on their kinematics. We present Near Infrared (NIR) K-band integral field observations of the blue-shifted HH 46/47 outflow base obtained using VLT/SINFONI with an angular resolution of 0".81. Our analysis focuses on [Fe II], H2 1-0 S(1), and, Br-gamma emission. We employ a wavelength recalibration technique based on OH telluric lines to probe the kinematics of the wide-angled flow with an accuracy of 1 km/s - 3 km/s. A velocity gradient of 10 km/s transverse to the outflow direction is confirmed in the wide-angled H2 outflow cavity. The H2 cavity peaks at radial velocities of -15 km/s to -30 km/s, and the atomic jet at v = -210 km/s. The outflow exhibits a layered structure; the high-velocity [Fe II] and Br-gamma jet is surrounded by a wide-angled H2 outflow cavity, which is in turn nested within the continuum emission and CO molecular outflow. The continuum emission and H2 outflow cavity are asymmetric with respect to the jet axis. We propose that the origin of the asymmetries and the velocity gradient detected in the wide-angled H2 cavity, is due to a wide-angled outflow or successive jet bowshocks expanding into an inhomogeneous ambient medium, or the presence of a secondary outflow. We eliminate outflow rotation as an exclusive origin of this velocity gradient due to large specific angular momenta values, J(r)= 3000 - 4000 km/s au calculated from 1" to 2" along the outflow. The observations reveal the complexities inherent in outflow systems, and the risk of attributing transverse velocity gradients solely to rotation.