One of the most important problems in the context of cataclysmic variables
(CVs) is the lack of observations of systems with periods between 2 and 3.12
hours, known as the period gap. The orbital evolution of CVs with periods
shorter than those in the gap is dominated by gravitational radiation while for
periods exceeding those of the gap it is dominated by magnetic braking of the
secondary star. Spruit & Ritter (1983) showed that as periods approach 3 hours
and secondary stars become fully convective a sharp decline in magnetic dynamo
and braking efficiency would result in such a gap. Recent X-ray observations
finding coronal magnetic energy dissipation is similar in fully convective and
partly radiative M dwarfs cast this theory into doubt. In this work, we use
Zeeman-Doppler imaging observations culled from the literature to show that the
complexity of the surface magnetic fields of rapidly rotating M dwarfs
increases with decreasing rotation period. Garraffo et al. (2018) have shown
that the efficiency of angular momentum loss of cool stars declines strongly
with increasing complexity of their surface magnetic field. By generating
synthetic CV populations, we show that the CV period gap can naturally arise as
a consequence of a rise in secondary star magnetic complexity near the long
period edge of the gap that renders a sharp decline in their angular momentum
loss rate.
Description
The Magnetic Nature of the Cataclysmic Variable Period Gap
%0 Generic
%1 garraffo2018magnetic
%A Garraffo, C.
%A Drake, J. J.
%A Alvarado-Gomez, J. D.
%A Moschou, S. P.
%A Cohen, O.
%D 2018
%K Magnetism
%T The Magnetic Nature of the Cataclysmic Variable Period Gap
%U http://arxiv.org/abs/1808.09450
%X One of the most important problems in the context of cataclysmic variables
(CVs) is the lack of observations of systems with periods between 2 and 3.12
hours, known as the period gap. The orbital evolution of CVs with periods
shorter than those in the gap is dominated by gravitational radiation while for
periods exceeding those of the gap it is dominated by magnetic braking of the
secondary star. Spruit & Ritter (1983) showed that as periods approach 3 hours
and secondary stars become fully convective a sharp decline in magnetic dynamo
and braking efficiency would result in such a gap. Recent X-ray observations
finding coronal magnetic energy dissipation is similar in fully convective and
partly radiative M dwarfs cast this theory into doubt. In this work, we use
Zeeman-Doppler imaging observations culled from the literature to show that the
complexity of the surface magnetic fields of rapidly rotating M dwarfs
increases with decreasing rotation period. Garraffo et al. (2018) have shown
that the efficiency of angular momentum loss of cool stars declines strongly
with increasing complexity of their surface magnetic field. By generating
synthetic CV populations, we show that the CV period gap can naturally arise as
a consequence of a rise in secondary star magnetic complexity near the long
period edge of the gap that renders a sharp decline in their angular momentum
loss rate.
@misc{garraffo2018magnetic,
abstract = {One of the most important problems in the context of cataclysmic variables
(CVs) is the lack of observations of systems with periods between 2 and 3.12
hours, known as the period gap. The orbital evolution of CVs with periods
shorter than those in the gap is dominated by gravitational radiation while for
periods exceeding those of the gap it is dominated by magnetic braking of the
secondary star. Spruit & Ritter (1983) showed that as periods approach 3 hours
and secondary stars become fully convective a sharp decline in magnetic dynamo
and braking efficiency would result in such a gap. Recent X-ray observations
finding coronal magnetic energy dissipation is similar in fully convective and
partly radiative M dwarfs cast this theory into doubt. In this work, we use
Zeeman-Doppler imaging observations culled from the literature to show that the
complexity of the surface magnetic fields of rapidly rotating M dwarfs
increases with decreasing rotation period. Garraffo et al. (2018) have shown
that the efficiency of angular momentum loss of cool stars declines strongly
with increasing complexity of their surface magnetic field. By generating
synthetic CV populations, we show that the CV period gap can naturally arise as
a consequence of a rise in secondary star magnetic complexity near the long
period edge of the gap that renders a sharp decline in their angular momentum
loss rate.},
added-at = {2018-08-30T16:21:50.000+0200},
author = {Garraffo, C. and Drake, J. J. and Alvarado-Gomez, J. D. and Moschou, S. P. and Cohen, O.},
biburl = {https://www.bibsonomy.org/bibtex/2b39e3b98d182e72e31c476d311d3bd36/superjenwinters},
description = {The Magnetic Nature of the Cataclysmic Variable Period Gap},
interhash = {5e56d4f04d2a9c8f3518da1cd1e64ca6},
intrahash = {b39e3b98d182e72e31c476d311d3bd36},
keywords = {Magnetism},
note = {cite arxiv:1808.09450Comment: 6 pages, 3 figures, submitted to ApJ},
timestamp = {2018-08-30T16:21:50.000+0200},
title = {The Magnetic Nature of the Cataclysmic Variable Period Gap},
url = {http://arxiv.org/abs/1808.09450},
year = 2018
}