Discovery of polarizations from ground state absorption lines: tracer of sub-Gauss magnetic field on 89Her

We report the identification of the polarization of ground state absorption lines from post-AGB 89~Hercules. Two ground state neutral iron lines are found to have counterintuitive high-amplitude polarizations and an unchanged polarization direction through the orbital period, as opposed to the patte...

Full description

Saved in:
Bibliographic Details
Published in:arXiv.org 2020-09
Main Authors: Zhang, Heshou, Gangi, Manuele, Leone, Francesco, Taylor, Andrew, Yan, Huirong
Format: Article
Language:English
Subjects:
Alignment
Ground state
Magnetic fields
Outflow
Solar magnetic field
Solar system
Topology
Universe
Zeeman effect
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:We report the identification of the polarization of ground state absorption lines from post-AGB 89~Hercules. Two ground state neutral iron lines are found to have counterintuitive high-amplitude polarizations and an unchanged polarization direction through the orbital period, as opposed to the pattern of polarizations of absorption lines from excited states, which are synchronized with the orbital phase owing to optical pumping. This can be explained with magnetic realignment on the ground state. The 3D mean magnetic field is thereby unveiled from the degree and direction of the polarizations of the two iron lines. The field strength is also constrained to be \(\lesssim 100\,{\rm mG}\). Our result has thus improved the accuracy by orders of magnitude compared to the previous \(10\,{\rm G}\) upper limit set by non-detection of the Zeeman effect.
ISSN:2331-8422
DOI:10.48550/arxiv.1903.08675