Disks around massive young stellar objects: are they common?

TL;DR

This study uses K-band polarimetric imaging to identify polarization disks around massive young stellar objects, supporting the presence of circumstellar disks and bipolar outflows in high-mass star formation.

Contribution

It provides new observational evidence of polarization disks around additional massive young stellar objects, confirming their role in the collapse and accretion process.

Findings

Polarization vectors are nearly centro-symmetric, indicating dominant illumination.

Three out of four sources show elongated low-polarization structures suggestive of disks.

The polarization disk in S140 IRS1 aligns with known outflow features, confirming its circumstellar nature.

Abstract

We present K-band polarimetric images of several massive young stellar objects at resolutions $\sim$ 0.1-0.5 arcsec. The polarization vectors around these sources are nearly centro-symmetric, indicating they are dominating the illumination of each field. Three out of the four sources show elongated low-polarization structures passing through the centers, suggesting the presence of polarization disks. These structures and their surrounding reflection nebulae make up bipolar outflow/disk systems, supporting the collapse/accretion scenario as their low-mass siblings. In particular, S140 IRS1 show well defined outflow cavity walls and a polarization disk which matches the direction of previously observed equatorial disk wind, thus confirming the polarization disk is actually the circumstellar disk. To date, a dozen massive protostellar objects show evidence for the existence of disks; our work add additional samples around MYSOs equivalent to early B-type stars.