2004/10/21 by Susanne Friedrich, S. Friedrich, Friedrich, S. +4
Physics and Astronomy · #Astro and Planetary Science #Astrophysics (astro-ph) #Astrophysics and Star Formation Studies #FOS: Physical sciences #Stellar, planetary, and galactic studies #astro-ph
paper · pdf · doi:10.48550/arxiv.astro-ph/0410507
4 LaTeX pages, 4 eps figures, to appear in the proceedings of the 14th European Workshop on White Dwarfs, eds. D. Koester and S. Moehler, ASP Conf. Series
arxiv created 2004/10/21 · openalex publication_date 2004/10/21 · arxiv updated 2009/12/01 · openalex created_date 2019/06/27 · openalex updated_date 2026/07/28
It is generally assumed that metals detected in the spectra of a few cool\nwhite dwarfs cannot be of primordial origin and must be accreted from the\ninterstellar medium. However, the observed abundances of hydrogen, which should\nalso be accreted from the interstellar medium, are lower than expected from\nmetal accretion. Magnetic fields are thought to be the reason for this\ndiscrepancy. We have therefore obtained circular polarization spectra of the\nhelium-rich white dwarfs GD40 and L745-46A, which both show strong metal lines\nas well as hydrogen. Whereas L745-46A might have a magnetic field of about\n-6900 G, which is about two times the field strength of 3000G necessary to\nrepell hydrogen at the Alfen radius, only an upper limit for the field strength\nof GD40 of 4000G (with 99% confidence) can be set which is far off the minimum\nfield strength of 144000G to repell hydrogen.\n