English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

White dwarf atmospheres are subjected to gravitational potentials around$10^5$ times larger than occur on Earth. They provide a unique environment inwhich to search for any possible variation in fundamental physics in thepresence of strong gravitational fields. However, a sufficiently strongmagnetic field will alter absorption line profiles and introduce additionaluncertainties in measurements of the fine structure constant. Estimating themagnetic field strength is thus essential in this context. Here we model theabsorption profiles of a large number of atomic transitions in the white dwarfphotosphere, including first-order Zeeman effects in the line profiles, varyingthe magnetic field as a free parameter. We apply the method to a highsignal-to-noise, high-resolution, far-ultraviolet HST/STIS spectrum of thewhite dwarf G191-B2B. The method yields a sensitive upper limit on its magneticfield of $B < 2300$ Gauss at the $3\sigma$ level. Using this upper limit wefind that the potential impact of quadratic Zeeman shifts on measurements ofthe fine structure constant in G191-B2B is 4 orders of magnitude belowlaboratory wavelength uncertainties.

Constraining the magnetic field on white dwarf surfaces; Zeeman effects and fine structure constant variation