Gap opening by planets in discs with magnetised winds. (arXiv:2206.11595v1 [astro-ph.EP])

Gap opening by planets in discs with magnetised winds. (arXiv:2206.11595v1 [astro-ph.EP])
<a href="http://arxiv.org/find/astro-ph/1/au:+Elbakyan_V/0/1/0/all/0/1">Vardan Elbakyan</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Wu_Y/0/1/0/all/0/1">Yinhao Wu</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Nayakshin_S/0/1/0/all/0/1">Sergei Nayakshin</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Rosotti_G/0/1/0/all/0/1">Giovanni Rosotti</a>

Planets open deep gaps in protoplanetary discs when their mass exceeds a gap
opening mass, $M_{rm gap}$. We use one- and two-dimensional simulations to
study planet gap opening in discs with angular momentum transport powered by
MHD disc winds. We parameterise the efficiency of the MHD disc wind angular
momentum transport through a dimensionless parameter $alpha_{rm dw}$, which
is an analogue to the turbulent viscosity $alpha_{rm v}$. We find that
magnetised winds are much less efficient in counteracting planet tidal torques
than turbulence is. For discs with astrophysically realistic values of
$alpha_{rm dw}$, $M_{rm gap}$ is always determined by the residual disc
turbulence, and is a factor of a few to ten smaller than usually obtained for
viscous discs. We introduce a gap opening criterion applicable for any values
of $alpha_{rm v}$ and $alpha_{rm dw}$ that may be useful for planet
formation population synthesis. We show that in discs powered by magnetised
winds, growing planets detach from the disc at planet masses below $sim
0.1M_{rm Jup}$ inside 10 AU. This promotes formation of super-Earth planets
rather than gas giants in this region, in particular precluding formation of
hot jupiters in situ. On larger scales, ALMA gap opening planet candidates may
be less massive than currently believed. Future high-resolution observations
with instruments such as the extended ALMA, ngVLA, and SKA are likely to show
abundant narrow annular features at $R < 10$ AU due to ubiquitous super-Earth
planets.

Planets open deep gaps in protoplanetary discs when their mass exceeds a gap
opening mass, $M_{rm gap}$. We use one- and two-dimensional simulations to
study planet gap opening in discs with angular momentum transport powered by
MHD disc winds. We parameterise the efficiency of the MHD disc wind angular
momentum transport through a dimensionless parameter $alpha_{rm dw}$, which
is an analogue to the turbulent viscosity $alpha_{rm v}$. We find that
magnetised winds are much less efficient in counteracting planet tidal torques
than turbulence is. For discs with astrophysically realistic values of
$alpha_{rm dw}$, $M_{rm gap}$ is always determined by the residual disc
turbulence, and is a factor of a few to ten smaller than usually obtained for
viscous discs. We introduce a gap opening criterion applicable for any values
of $alpha_{rm v}$ and $alpha_{rm dw}$ that may be useful for planet
formation population synthesis. We show that in discs powered by magnetised
winds, growing planets detach from the disc at planet masses below $sim
0.1M_{rm Jup}$ inside 10 AU. This promotes formation of super-Earth planets
rather than gas giants in this region, in particular precluding formation of
hot jupiters in situ. On larger scales, ALMA gap opening planet candidates may
be less massive than currently believed. Future high-resolution observations
with instruments such as the extended ALMA, ngVLA, and SKA are likely to show
abundant narrow annular features at $R < 10$ AU due to ubiquitous super-Earth
planets.

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