Two new white dwarfs with variable magnetic Balmer emission lines

Abstract

We report the discovery of two apparently isolated stellar remnants that exhibit rotationally modulated magnetic Balmer emission, adding to the emerging DAHe class of white dwarf stars. While the previously discovered members of this class show Zeeman-split triplet emission features corresponding to single magnetic field strengths, these two new objects exhibit significant fluctuations in their apparent magnetic field strengths with variability phase. The Zeeman-split hydrogen emission lines in LP 705-64 broaden from 9.4 to 22.2 MG over an apparent spin period of 72.629 min. Similarly, WD J143019.29-562358.33 varies from 5.8 to 8.9 MG over its apparent 86.394 min rotation period. This brings the DAHe class of white dwarfs to at least five objects, all with effective temperatures within 500 K of 8000 K and masses ranging from 0.65 to 0.83 M☉