Adaptive Optics Imaging of VY Canis Majoris at 2 - 5 micron with LBT/LMIRCam

TL;DR

This study uses adaptive optics imaging in the 2-5 micron range to analyze the structure and scattering properties of the Southwest Clump around the red supergiant VY Canis Majoris, revealing insights into its mass and ejection history.

Contribution

First detailed AO imaging of VY Canis Majoris in the 2-5 micron range, modeling the scattering properties and estimating the mass of the Southwest Clump.

Findings

The Southwest Clump appears prominently in all observed bands.

Its brightness is mainly due to scattering, with limited thermal emission.

Estimated mass of the Clump ranges from 5E-03 to 2.5E-02 solar masses.

Abstract

We present adaptive optics images of the extreme red supergiant VY Canis Majoris in the Ks, L' and M bands (2.15 to 4.8 micron) made with LMIRCam on the Large Binocular Telescope (LBT). The peculiar "Southwest Clump" previously imaged from 1 to 2.2 micron appears prominently in all three filters. We find its brightness is due almost entirely to scattering, with the contribution of thermal emission limited to at most 25%. We model its brightness as optically thick scattering from silicate dust grains using typical size distributions. We find a lower limit mass for this single feature of 5E-03 Msun to 2.5E-02 Msun depending on the assumed gas-to-dust ratio. The presence of the Clump as a distinct feature with no apparent counterpart on the other side of the star is suggestive of an ejection event from a localized region of the star and is consistent with VY CMa's history of asymmetric high mass loss events.