The nature of HHL 73 from optical imaging and Integral Field Spectroscopy

TL;DR

This study investigates the Herbig-Haro-like object 73 using optical imaging, integral field spectroscopy, and radio observations, revealing complex kinematics and morphology consistent with a bipolar outflow, and proposing it as a true Herbig-Haro object.

Contribution

The paper provides detailed imaging and spectroscopic analysis of HHL73, demonstrating its bipolar outflow structure and confirming its classification as a Herbig-Haro object with new kinematic insights.

Findings

HHL73 has a comet-shaped morphology with a microjet feature.

Spectroscopy shows complex velocity components indicating bipolar outflow.

Radio emission aligns with the redshifted gas of HHL73.

Abstract

We present new results on the nature of the Herbig-Haro-like object 73 (HHL73, also known as [G84b] 11) based on narrow-band CCD H_alpha and [SII] images of the HHL73 field, and Integral Field Spectroscopy and radio continuum observations at 3.6 cm covering the emission of the HHL 73 object. The CCD images allow us to resolve the HHL 73 comet-shaped morphology into two components and a collimated emission feature of ~4" long, reminiscent of a microjet. The IFS spectra of HHL 73 showed emission lines characteristic of the spectra of Herbig--Haro objects. The kinematics derived for HHL~73 are complex. The profiles of the [SII] lambda6717, 6731AA lines were well fitted with a model of three Gaussian velocity components peaking at -100, -20 and +35 km/s. We found differences among the spatial distribution of the kinematic components that are compatible with the emission from a bipolar outflow with two blueshifted (low- and high-velocity) components. Extended radio continuum emission at 3.6 cm was detected showing a distribution in close agreement with the HHL~73 redshifted gas. From the results discussed here, we propose HHL 73 to be a true HH object. IRAS 21432+4719, offset 30 arcsec northeast from the HHL 73 apex, is the most plausible candidate to be driving HHL 73, although the evidence is not conclusive.