A Documentary of High-Mass Star Formation: Probing the Dynamical Evolution of Orion Source I on 10-100 AU Scales using SiO Masers

TL;DR

This study uses multi-epoch SiO maser observations to map the 3D dynamical evolution of material around a high-mass YSO in Orion, providing insights into the accretion and outflow processes at scales of 10-100 AU.

Contribution

It presents the first multi-epoch VLBA study of SiO masers around a high-mass YSO, revealing detailed dynamical structures and supporting disk-mediated accretion models.

Findings

Evidence for disk-mediated accretion in high-mass star formation.

Proper motions of SiO maser spots reveal outflow dynamics.

Temporal monitoring shows evolving physical conditions in the outflow region.

Abstract

A comprehensive picture of high-mass star formation has remained elusive, in part because examples of high-mass YSOs tend to be relatively distant, deeply embedded, and confused with other emission sources. These factors have impeded dynamical investigations within tens of AU of high-mass YSOs--scales that are critical for probing the interfaces where outflows from accretion disks are launched and collimated. Using observations of SiO masers obtained with the VLA and the VLBA, the KaLYPSO project is overcoming these limitations by mapping the structure and dynamical/temporal evolution of the material 10-1000 AU from the nearest high-mass YSO: Radio Source I in the Orion BN/KL region. Our data include ~40 epochs of VLBA observations over a several-year period, allowing us to track the proper motions of individual SiO maser spots and to monitor changes in the physical conditions of the emitting material with time. Ultimately these data will provide 3-D maps of the outflow structure over approximately 30% of the outflow crossing time. Here we summarize recent results from the KaLYPSO project, including evidence that high-mass star formation is occurring via disk-mediated accretion.