A survey of IRAS young stellar object candidates. Searching for large-scale Herbig-Haro objects

TL;DR

This survey investigates large-scale Herbig-Haro objects around IRAS sources to understand young stellar object outflows, revealing new HH detections, clarifying emission origins, and refining source distances through wide-field optical imaging.

Contribution

The paper provides homogeneous deep imaging of 15 IRAS sources, identifying new HH objects, clarifying emission mechanisms, and updating source data, which advances understanding of stellar outflows and their large-scale structures.

Findings

HH emission detected in 6 out of 15 fields.

Extended emission around 9 IRAS targets is scattered light.

Refined distances for 7 sources are reported.

Abstract

Jets and outflows are associated with young stellar objects across the stellar mass spectrum, from brown dwarf protostars to massive, Ae/Be stars. Frequently, the jet morphology is spatially discontinuous because of the temporal variability of the ejection from the driving source. Images covering a wide field of view around the jet driving-source are useful to map the large-scale jet emission and to explore the mass ejection history. The aim of this work was to search for large-scale optical Herbig-Haro (HH) objects lying in a wide field around a sample of IRAS sources, candidates to trace young stellar objects. Deep, narrow-band images through the H$\alpha$ and [SII] emission lines, and through an off-line continuum filter, covering a wide ($\sim15'$) field around the IRAS targets were acquired. The images in the three filters were analyzed to identify shock-excited line emission (i.e., HH) in contrast to scattered line emission. New images of a sample of fifteen IRAS sources, obtained in an homogeneous way are presented. HH emission was detected in six fields, and the astrometry of the knot features is given. The nature of the extended emission as scattered emission around nine of the IRAS targets is confirmed. For seven IRAS sources, with unclear optical counterpart, a more plausible counterpart is proposed. A refined value of the source distance is reported for seven targets. An update of the main data available for each of the sampled fields, including images from public data archives, is also presented.