Linear Spectropolarimetry and the Circumstellar Media of Young and Massive Stars

TL;DR

Linear spectropolarimetry is a valuable observational technique for studying the geometry and physical properties of circumstellar environments around young and massive stars, especially when direct imaging is not feasible.

Contribution

This review highlights the application of emission-line polarimetry in constraining the structures and physical conditions of various circumstellar media.

Findings

Spectropolarimetry reveals geometrical asymmetries in accretion disks.

Clumping in stellar winds can be diagnosed through polarization.

Aspherical outflows are characterized in massive star progenitors.

Abstract

Linear spectropolarimetry is a powerful tool to probe circumstellar structures on spatial scales that cannot yet be achieved through direct imaging. In this review I discuss the role that emission-line polarimetry can play in constraining geometrical and physical properties of a wide range of circumstellar environments, varying from the accretion disks around pre-main sequence T Tauri and Herbig Ae/Be stars, to the issue of stellar wind clumping, and the aspherical outflows from the massive star progenitors of supernovae and long gamma-ray bursts at low metallicity.