Effect of Different Angular Momentum Transport mechanisms on the Distribution of Water in Protoplanetary Disks. (arXiv:1903.06746v1 [astro-ph.EP])

Effect of Different Angular Momentum Transport mechanisms on the Distribution of Water in Protoplanetary Disks. (arXiv:1903.06746v1 [astro-ph.EP])
<a href="http://arxiv.org/find/astro-ph/1/au:+Kalyaan_A/0/1/0/all/0/1">Anusha Kalyaan</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Desch_S/0/1/0/all/0/1">Steven J. Desch</a>

The snow line in a protoplanetary disk demarcates regions with H$_2$O ice
from regions with H$_2$O vapor. Where a planet forms relative to this location
determines how much water and other volatiles it forms with. Giant planet
formation may be triggered at the water snow line if vapor diffuses outward and
is cold-trapped beyond the snow line faster than icy particles can drift
inward. In this study we investigate the distribution of water across the snow
line, considering three different radial profiles of the turbulence parameter
$alpha(r)$, corresponding to three different angular momentum transport
mechanisms. We consider the radial transport of water vapor and icy particles
by diffusion, advection, and drift. We show that even for similar values of
$alpha$, the gradient of $alpha$(r) across the snow line significantly
changes the snow line location, the sharpness of the volatile gradient across
the snow line, and the final water/rock ratio in planetary bodies. A profile of
radially decreasing $alpha$, consistent with transport by hydrodynamic
instabilities plus magnetic disk winds, appears consistent with the
distribution of water in the solar nebula, with monotonically-increasing radial
water content and a diverse population of asteroids with different water
content. We argue that $Sigma(r)$ and water abundance $N_{rm H_2O}(r)/N_{rm
H_2}(r)$ are likely diagnostic of $alpha(r)$ and thus the mechanism for
angular momentum transport in inner disks.

The snow line in a protoplanetary disk demarcates regions with H$_2$O ice
from regions with H$_2$O vapor. Where a planet forms relative to this location
determines how much water and other volatiles it forms with. Giant planet
formation may be triggered at the water snow line if vapor diffuses outward and
is cold-trapped beyond the snow line faster than icy particles can drift
inward. In this study we investigate the distribution of water across the snow
line, considering three different radial profiles of the turbulence parameter
$alpha(r)$, corresponding to three different angular momentum transport
mechanisms. We consider the radial transport of water vapor and icy particles
by diffusion, advection, and drift. We show that even for similar values of
$alpha$, the gradient of $alpha$(r) across the snow line significantly
changes the snow line location, the sharpness of the volatile gradient across
the snow line, and the final water/rock ratio in planetary bodies. A profile of
radially decreasing $alpha$, consistent with transport by hydrodynamic
instabilities plus magnetic disk winds, appears consistent with the
distribution of water in the solar nebula, with monotonically-increasing radial
water content and a diverse population of asteroids with different water
content. We argue that $Sigma(r)$ and water abundance $N_{rm H_2O}(r)/N_{rm
H_2}(r)$ are likely diagnostic of $alpha(r)$ and thus the mechanism for
angular momentum transport in inner disks.

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