Ultraviolet Spectropolarimetry with Polstar: Massive Star Binary Colliding Winds

TL;DR

This paper discusses how the Polstar mission's ultraviolet spectropolarimetry can significantly improve understanding of massive star winds and their mass-loss rates, especially in binary systems with colliding winds.

Contribution

It proposes using Polstar's spectropolarimetric observations to precisely constrain the physics of colliding stellar winds in massive binaries.

Findings

Enhanced accuracy in measuring mass-loss rates.

Detailed wind velocity structure characterization.

Sample of 17 targets for comprehensive wind studies.

Abstract

As sources of chemical enrichment, ionizing radiation and energetic feedback, massive stars drive the ecology of their host galaxies despite their relative rarity, additionally to yielding compact remnants, which can generate gravitational waves. The evolution of massive stars is crucially informed by their detailed mass-loss history; however, wind structures on a variety of scales cause important uncertainties on their mass-loss rates. Binary systems can place further constraints on the mass-loss properties of massive stars, especially colliding-wind binaries. In this paper, we review how the proposed MIDEX-scale mission Polstar can critically constrain the physics of colliding winds (and hence radiatively-driven winds in general) with ultraviolet spectropolarimetric observations, providing an unprecedented improvement on the accuracy of the determination of both mass-loss rates and the velocity structure of the winds of massive stars. We propose a sample of 17 targets that will allow us to study a variety of wind-colliding systems spanning a large parameter space using the spatial information yielded by both spectroscopic and polarimetric data obtained with Polstar.