Salt-bearing disk candidates around high-mass young stellar objects

TL;DR

This study investigates the occurrence of salt-bearing molecular emissions in high-mass young stellar objects, revealing that such salty disks are present in some cases but not universally, and providing new detections of these species.

Contribution

The paper reports five new detections of salt and related molecules in high-mass star-forming regions, expanding the known sample of salty disk candidates and analyzing their properties.

Findings

Salt-bearing molecules are detected in some high-mass YSO disks.

Detected molecules are spatially coincident and often detected together.

Salty disks are neither rare nor ubiquitous among high-mass YSOs.

Abstract

Molecular lines tracing the orbital motion of gas in a well-defined disk are valuable tools for inferring both the properties of the disk and the star it surrounds. Lines that arise only from a disk, and not also from the surrounding molecular cloud core that birthed the star or from the outflow it drives, are rare. Several such emission lines have recently been discovered in one example case, those from NaCl and KCl salt molecules. We studied a sample of 23 candidate high-mass young stellar objects (HMYSOs) in 17 high-mass star-forming regions to determine how frequently emission from these species is detected. We present five new detections of water, NaCl, KCl, PN, and SiS from the innermost regions around the objects, bringing the total number of known briny disk candidates to nine. Their kinematic structure is generally disk-like, though we are unable to determine whether they arise from a disk or outflow in the sources with new detections. We demonstrate that these species are spatially coincident in a few resolved cases and show that they are generally detected together, suggesting a common origin or excitation mechanism. We also show that several disks around HMYSOs clearly do not exhibit emission in these species. Salty disks are therefore neither particularly rare in high-mass disks, nor are they ubiquitous.