High-resolution Linear Spectropolarimetry of Red Supergiant VY CMa: Identification of Atomic and Molecular Features

Abstract We present a high-resolution optical spectropolarimetric observation of the red supergiant VY CMa. The spectrum CMa contains numerous emission features that are mainly due to molecular bands TiO, ScO, and VO. In addition, lines Ba ii , Ca i Na K i, Rb identified in spectrum. Our shows all exhibit very large abrupt linear polarization reduction, i.e., depolarization, across band heads up 10% or higher with respect continuum level. observations demonstrate clearly associated largest depolarization. Using this property together simulated TiO we able identify most broad as emission. also reveal previously unknown phenomenon atomic either absoprtion depolarization line profile, doublet showing almost complete observed pattern is similar among lines, even though spectral belong different species. Together recent high resolution observations, discuss origin suggest absorption scattering complex circumstellar environment CMa, especially dense dusty clumps located on plane sky.