An infrared view of (candidate accretion) disks around massive young stars

TL;DR

This paper uses near- and mid-infrared observations to study the circumstellar disks and envelopes around massive young stellar objects, revealing their structure, kinematics, and evolutionary status.

Contribution

It provides new infrared observational evidence for the presence and characteristics of disks and envelopes around massive YSOs, enhancing understanding of their formation processes.

Findings

Detection of disk-wind signatures via hydrogen emission lines

CO band-head profiles indicating Keplerian disks

Confirmation of cold envelopes through CO absorption lines

Abstract

Near-infrared surveys of high-mass star-forming regions start to shed light onto their stellar content. A particular class of objects found in these regions, the so-called massive Young Stellar Objects (YSOs) are surrounded by dense circumstellar material. Several near- and mid-infrared diagnostic tools are used to infer the physical characteristics and geometry of this circumstellar matter. Near-infrared hydrogen emission lines provide evidence for a disk-wind. The profiles of the first overtone of the CO band-heads, originating in the inner 10 AU from the central star, are well fitted assuming a keplerian rotating disk. The mid-infrared spectral energy distribution requires the presence of a more extended envelope containing dust at a temperature of about 200 K. CRIRES observations of CO fundamental absorption lines confirm the presence of a cold envelope. We discuss the evolutionary status of these objects.