Trapping (sub-)Neptunes similar to TOI-216b at the inner disk rim Implications for the disk viscosity and the Neptunian desert

Result code in IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F00216208%3A11320%2F22%3A10456197" target="_blank" >RIV/00216208:11320/22:10456197 - isvavai.cz</a>

Result on the web

<a href="https://verso.is.cuni.cz/pub/verso.fpl?fname=obd_publikace_handle&handle=hYeymzpOSl" target="_blank" >https://verso.is.cuni.cz/pub/verso.fpl?fname=obd_publikace_handle&handle=hYeymzpOSl</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1051/0004-6361/202244461" target="_blank" >10.1051/0004-6361/202244461</a>

Result language

angličtina

Original language name

Trapping (sub-)Neptunes similar to TOI-216b at the inner disk rim Implications for the disk viscosity and the Neptunian desert

Original language description

Context. The occurrence rate of observed sub-Neptunes has a break at 0.1 au, which is often attributed to a migration trap at the inner rim of protoplanetary disks where a positive co-rotation torque prevents inward migration. Aims. We argue that conditions in inner disk regions are such that sub-Neptunes are likely to open gaps, lose the support of the co-rotation torque as their co-rotation regions become depleted, and the trapping efficiency then becomes uncertain. We study what it takes to trap such gap-opening planets at the inner disk rim. Methods. We performed 2D locally isothermal and non-isothermal hydrodynamic simulations of planet migration. A viscosity transition was introduced in the disk to (i) create a density drop and (ii) mimic the viscosity increase as the planet migrated from a dead zone towards a region with active magneto-rotational instability (MRI). We chose TOI-216b as a Neptune-like upper-limit test case, but we also explored different planetary masses, both on fixed and evolving orbits. Results. For planet-to-star mass ratios q similar or equal to (4-8) x 10(-5), the density drop at the disk rim becomes reshaped due to a gap opening and is often replaced with a small density bump centred on the planet&apos;s co-rotation. Trapping is possible only if the bump retains enough gas mass and if the co-rotation region becomes azimuthally asymmetric, with an island of librating streamlines that accumulate a gas overdensity ahead of the planet. The overdensity exerts a positive torque that can counteract the negative torque of spiral arms. Under suitable conditions, the overdensity turns into a Rossby vortex. In our model, efficient trapping depends on the alpha viscosity and its contrast across the viscosity transition. In order to trap TOI-216b, alpha(DZ) = 10(-3) in the dead zone requires alpha(MRI) greater than or similar to 5 x 10(-2) in the MRI-active zone. If alpha(DZ) = 5 x 10(-4), alpha(MRI) greater than or similar to 7.5 x 10(-2) is needed. Conclusions. We describe a new regime of a migration trap relevant for massive (sub-)Neptunes that puts valuable constraints on the levels of turbulent stress in the inner part of their natal disks.

Czech name

—

Czech description

—

Type

J_imp - Article in a specialist periodical, which is included in the Web of Science database

CEP classification

—

OECD FORD branch

10308 - Astronomy (including astrophysics,space science)

Project

<a href="/en/project/GM21-23067M" target="_blank" >GM21-23067M: Hydrodynamic interactions of planets with protoplanetary disks and the origin of close-in exoplanetary systems</a><br>

Continuities

P - Projekt vyzkumu a vyvoje financovany z verejnych zdroju (s odkazem do CEP)

Publication year

2022

Confidentiality

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Name of the periodical

Astronomy &amp; Astrophysics

ISSN

0004-6361

e-ISSN

1432-0746

Volume of the periodical

666

Issue of the periodical within the volume

říjen

Country of publishing house

FR - FRANCE

Number of pages

20

Pages from-to

A63

UT code for WoS article

000865835600002

EID of the result in the Scopus database

2-s2.0-85141652300