Dissecting Massive YSOs with Mid-Infrared Interferometry

TL;DR

This study uses mid-infrared interferometry to resolve the innermost regions of massive young stellar objects, providing new insights into their structure and dust emission at scales of 20 milliarcseconds.

Contribution

First application of MIDI interferometry to measure the compact thermal emission regions of massive YSOs, advancing understanding of their innermost structures.

Findings

Resolved objects with sizes of 30-50 mas

Quantified thermal emission extent from warm circumstellar dust

Provided new constraints on the compactness of emission in pre-UCHII regions

Abstract

The very inner structure of massive YSOs is difficult to trace. With conventional observational methods we often identify structures still several hundreds of AU in size. But we also need information about the innermost regions where the actual mass transfer onto the forming high-mass star occurs. An innovative way to probe these scales is to utilise mid-infrared interferometry. Here, we present first results of our MIDI GTO programme at the VLTI. We observed 10 well-known massive YSOs down to scales of 20 mas. We clearly resolve these objects which results in low visibilities and sizes in the order of 30 - 50 mas. Thus, with MIDI we can for the first time quantify the extent of the thermal emission from the warm circumstellar dust and thus calibrate existing concepts regarding the compactness of such emission in the pre-UCHII region phase. Special emphasis will be given to the BN-type object M8E-IR where our modelling is most advanced and where there is indirect evidence for a strongly bloated central star.