Photospheric Hanle diagnostic of weak magnetic dipoles in stars

Abstract

Diagnostic techniques for stellar magnetic fields based upon spectropolarimetry. We propose and explore a new technique based upon the linear polarization emitted in Hanle-sensitive lines in disk-integrated stars where a dipolar magnetic field breaks the rotational symmetry of the resonance scattering polarization. A star with a simple dipolar field and a 1-0 spectral line are used to compute polarization amplitudes and angles.Predicted amplitudes are low but within reach of present instruments. A new application of the Hanle effect is proposed and analyzed, a tool that allows measuring of some of the weakest stellar magnetic fields.

6 pages, 3 figures. Accepted for publication in A&A

References in corpus (4)

• A Substantial Amount of Hidden Magnetic Energy in the Quiet Sun
• The weak magnetic field of the O9.7 supergiant zeta Orionis A
• Origin and evolution of magnetars
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• Time-Dependent Behavior of Linear Polarization in Unresolved Photospheres, With Applications for The Hanle Effect
• Ultraviolet Spectropolarimetry: Investigating stellar magnetic field diagnostics
• Faraday Rotation Distributions from Stellar Magnetism in Wind-Blown Bubbles
• Synthetic polarimetric spectra from stellar prominences