Rotation plays a role in the generation of magnetic fields in single white dwarfs
Recent surveys of close white dwarf binaries as well as single white dwarfs have provided evidence for the late appearance of magnetic fields in white dwarfs, and a possible generation mechanism a crystallization and rotation-driven dynamo has been suggested. A key prediction of this dynamo is that...
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Main Authors | , , , , , , , |
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Format | Journal Article |
Language | English |
Published |
26.01.2024
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Subjects | |
Online Access | Get full text |
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Summary: | Recent surveys of close white dwarf binaries as well as single white dwarfs
have provided evidence for the late appearance of magnetic fields in white
dwarfs, and a possible generation mechanism a crystallization and
rotation-driven dynamo has been suggested. A key prediction of this dynamo is
that magnetic white dwarfs rotate, at least on average, faster than their
non-magnetic counterparts and/or that the magnetic field strength increases
with rotation. Here we present rotation periods of ten white dwarfs within 40
pc measured using photometric variations. Eight of the light curves come from
TESS observations and are thus not biased towards short periods, in contrast to
most period estimates that have been reported previously in the literature.
These TESS spin periods are indeed systematically shorter than those of
non-magnetic white dwarfs. This means that the crystallization and
rotation-driven dynamo could be responsible for a fraction of the magnetic
fields in white dwarfs. However, the full sample of magnetic white dwarfs also
contains slowly rotating strongly magnetic white dwarfs which indicates that
another mechanism that leads to the late appearance of magnetic white dwarfs
might be at work, either in addition to or instead of the dynamo. The
fast-spinning and massive magnetic white dwarfs that appear in the literature
form a small fraction of magnetic white dwarfs, and probably result from a
channel related to white dwarf mergers. |
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DOI: | 10.48550/arxiv.2401.15158 |