Early Planet Formation in Embedded Disks (eDisk). XIX. Structures of molecular outflows

Abstract

As part of the ALMA Large Program "Early Planet Formation in Embedded Disks" (eDisk), 12CO (2 - 1) was observed towards 19 nearby low-mass protostars. Of these objects, 15 sources are found to show molecular outflow emission. Based on their morphological and kinematical structures, the CO outflows are classified into three types: a wind-driven shell, where ambient material is swept up by a wide-angle wind from the star, a bow shock, and a slow disk wind, which is a conical or parabolic flow with onion-like velocity structure. We categorize 11 outflows as a slow disk wind, 7 as a wind-driven shell, and 1 as a bow shock. Four of these outflows were found to show signs of both slow disk wind and wind-driven shell characteristics. Five objects show misalignment between the red- and blue-shifted outflows. Seven objects show significant misalignment between the outflow axis (either or both of the red- and blue-shifted outflows) and the minor axis of the dust continuum emission around the protostar. For the objects showing wind-driven shell emission, we compare simple parametrized models with the observations to derive physical properties of the observed shells, such as their dynamical ages. This shows evidence of a time variability in the outflows, such as changes in their direction. In some objects, large differences are seen between the properties of the red- and blue-shifted outflows, possibly indicating differences in the properties of the ambient medium with which the outflow interacts.