Differential Rotation in Convective Envelopes: Constraints from Eclipsing Binaries. (arXiv:1911.01431v1 [astro-ph.SR])
<a href="http://arxiv.org/find/astro-ph/1/au:+Jermyn_A/0/1/0/all/0/1">Adam S. Jermyn</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Tayar_J/0/1/0/all/0/1">Jamie Tayar</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Fuller_J/0/1/0/all/0/1">Jim Fuller</a>
Over time, tides synchronize the rotation periods of stars in a binary system
to the orbital period. However, if the star exhibits differential rotation then
only a portion of it can rotate at the orbital period, so the rotation period
at the surface may not match the orbital period. The difference between the
rotation and orbital periods can therefore be used to infer the extent of the
differential rotation. We use a simple parameterization of differential
rotation in stars with convective envelopes in circular orbits to predict the
difference between the surface rotation period and the orbital period.
Comparing this parameterization to observed eclipsing binary systems, we find
that in the surface convection zones of stars in short-period binaries there is
very little radial differential rotation, with $|rpartial_r ln Omega| <
0.02$. This holds even for longer orbital periods, though it is harder to say
which systems are synchronized at long periods, and larger differential
rotation is degenerate with asynchronous rotation.
Over time, tides synchronize the rotation periods of stars in a binary system
to the orbital period. However, if the star exhibits differential rotation then
only a portion of it can rotate at the orbital period, so the rotation period
at the surface may not match the orbital period. The difference between the
rotation and orbital periods can therefore be used to infer the extent of the
differential rotation. We use a simple parameterization of differential
rotation in stars with convective envelopes in circular orbits to predict the
difference between the surface rotation period and the orbital period.
Comparing this parameterization to observed eclipsing binary systems, we find
that in the surface convection zones of stars in short-period binaries there is
very little radial differential rotation, with $|rpartial_r ln Omega| <
0.02$. This holds even for longer orbital periods, though it is harder to say
which systems are synchronized at long periods, and larger differential
rotation is degenerate with asynchronous rotation.
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