CFHT UM2019 - Presentation Details

Abstract Details

Title: Studying weak magnetic fields in white dwarf stars with ESPaDOnS

Presenter: John Landstreet


Almost 50 years after the first discovery of a 300 MG magnetic field in a white dwarf (WD), little is known about fields weaker than about 1 MG. We have found that ESPaDOnS is a powerful tool for searching for and studying such fields in the brighter WDs (V < 15). We have set an upper limit of ~200 G for a possible surface field on the brightest isolated WD, 40 Eri B. We have surveyed several dozen WDs with uncertainties of a few kG or less in the longitudinal fields , and discovered weak fields in WD2047 372 and WD1105-340. We have used ESPaDOnS data to find rotation periods and to model the surface fields of WD2047 372 and WD2359-434, and have data for further modelling. ESPaDOnS is able to compete effectively even with the FORS spectropolarimeter on an 8-m ESO telescope.