The nature of HH 223 from long-slit spectroscopy

TL;DR

This study uses long-slit spectroscopy to analyze HH 223, a nebular emission in L723, revealing it as a supersonic, shock-excited outflow driven by embedded young stellar objects, clarifying its nature.

Contribution

First detailed spectroscopic analysis of HH 223, confirming its shock-excited, high-velocity outflow nature and physical conditions at small scales.

Findings

HH 223 exhibits intermediate/high excitation emission.

Emission velocities range from -60 to -130 km/s.

Spectroscopy confirms HH 223 as a shock-excited outflow.

Abstract

HH 223 is a knotty, wiggling nebular emission of ~30" length found in the L723 star-forming region. It lies projected onto the largest blueshifted lobe of the cuadrupolar CO outflow powered by a low-mass YSO system embedded in the core of L723. We analysed the physical conditions and kinematics along HH 223 with the aim of disentangling whether the emission arises from shock-excited, supersonic gas characteristic of a stellar jet, or is only tracing the wall cavity excavated by the CO outflow. We performed long-slit optical spectroscopy along HH 223, crossing all the bright knots (A to E) and part of the low-brightness emission nebula (F filament). One spectrum of each knot, suitable to characterize the nature of its emission, was obtained. The physical conditions and the radial velocity of the HH 223 emission along the slits were also sampled at smaller scale (0.6") than the knot sizes. {The spectra of all the HH 223 knots appear as those of the intermediate/high excitation Herbig-Haro objects. The emission is supersonic, with blueshifted peak velocities ranging from -60 to -130 km/s. Reliable variations in the kinematics and physical conditions at smaller scale that the knot sizes are also found. The properties of the HH 223 emission derived from the spectroscopy confirm the HH nature of the object, the supersonic optical outflow most probably also being powered by the YSOs embedded in the L723 core.