Spectropolarimetry of Beta Lyrae: Constraining the Location of the Hot Spot and Jets

TL;DR

This study uses six years of spectropolarimetric data to analyze Beta Lyrae's complex disk-jet structure, revealing the hot spot's location and the distribution of hot gas, enhancing understanding of mass transfer in binary systems.

Contribution

It provides new spectropolarimetric insights into Beta Lyrae's disk, hot spot, and jet geometry, improving models of mass transfer in semi-detached binaries.

Findings

Identified the hot spot location on the accretion disk.

Mapped the distribution of hot line-emitting gas.

Confirmed bipolar outflows through polarimetry.

Abstract

Beta Lyrae is an eclipsing, semi-detached binary system whose state of active mass transfer can reveal details of the nonconservative evolution of binary stars. Roche lobe overflow has caused the system to evolve to a complex state. A thick accretion disk almost completely obscures the secondary, mass-gaining star while the rapid mass transfer likely drives mass loss through the system's bipolar outflows. Polarimetry can provide important information about the physical structure of complex systems; in fact, the discovery of bipolar outflows in beta Lyrae was confirmed through polarimetry. Here we present results from 6 years of new and recalibrated spectropolarimetric data taken with the University of Wisconsin's Half-Wave Spectropolarimeter (HPOL). We discuss their implications for our current understanding of the system's disk-jet geometry. Using both broadband and line polarization analysis techniques, we derive new information about the structure of the disk, the presence and location of a hot spot, and the distribution of hot line-emitting gas.