Long-term stability of Enceladus' uneven ice shell

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F00216208%3A11320%2F19%3A10403988" target="_blank" >RIV/00216208:11320/19:10403988 - isvavai.cz</a>

Výsledek na webu

<a href="https://verso.is.cuni.cz/pub/verso.fpl?fname=obd_publikace_handle&handle=z.L6XwmF0T" target="_blank" >https://verso.is.cuni.cz/pub/verso.fpl?fname=obd_publikace_handle&handle=z.L6XwmF0T</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1016/j.icarus.2018.10.003" target="_blank" >10.1016/j.icarus.2018.10.003</a>

Jazyk výsledku

angličtina

Název v původním jazyce

Long-term stability of Enceladus' uneven ice shell

Popis výsledku v původním jazyce

We present a new model of Enceladus&apos; internal structure based on the recent shape model by Tajeddine et al. (2017) and the gravity model by Iess et al. (2014). Assuming that the rocky core is homogeneous and in hydrostatic equilibrium, we derive a set of structural models that accurately reproduce the main characteristics of Enceladus&apos; gravity field. In order to restrict the range of acceptable models we analyze the degree of compensation (ratio of the bottom to the surface load) at spherical harmonic degrees well constrained by the gravity data. In agreement with previous studies, we find that Enceladus&apos; ice shell is close to equilibrium, with the degree of compensation approaching one for models with a hydrostatic core having a radius between 190 km and 195 km. By computing the flow of ice driven by variations in hydrostatic pressure on the ice water/interface, we demonstrate that the ice shell is in steady state, as suggested by the gravity and shape data, only if the viscosity of ice at the melting temperature is equal to or higher than 3 x 10(14) Pa s, corresponding to diffusion creep with a grain size of 1 mm or larger. The topographic anomalies are maintained by phase changes at the ice/water interface with a melting/freezing rate of a few mm/yr or smaller. This process is controlled by the heat flux at the top of the ocean, characterized by a strong degree-2 zonal component with amplitudes exceeding 60 rnW/m(2) in both south and north polar regions.

Název v anglickém jazyce

Long-term stability of Enceladus' uneven ice shell

Popis výsledku anglicky

We present a new model of Enceladus&apos; internal structure based on the recent shape model by Tajeddine et al. (2017) and the gravity model by Iess et al. (2014). Assuming that the rocky core is homogeneous and in hydrostatic equilibrium, we derive a set of structural models that accurately reproduce the main characteristics of Enceladus&apos; gravity field. In order to restrict the range of acceptable models we analyze the degree of compensation (ratio of the bottom to the surface load) at spherical harmonic degrees well constrained by the gravity data. In agreement with previous studies, we find that Enceladus&apos; ice shell is close to equilibrium, with the degree of compensation approaching one for models with a hydrostatic core having a radius between 190 km and 195 km. By computing the flow of ice driven by variations in hydrostatic pressure on the ice water/interface, we demonstrate that the ice shell is in steady state, as suggested by the gravity and shape data, only if the viscosity of ice at the melting temperature is equal to or higher than 3 x 10(14) Pa s, corresponding to diffusion creep with a grain size of 1 mm or larger. The topographic anomalies are maintained by phase changes at the ice/water interface with a melting/freezing rate of a few mm/yr or smaller. This process is controlled by the heat flux at the top of the ocean, characterized by a strong degree-2 zonal component with amplitudes exceeding 60 rnW/m(2) in both south and north polar regions.

Druh

J_imp - Článek v periodiku v databázi Web of Science

CEP obor

—

OECD FORD obor

10500 - Earth and related environmental sciences

Projekt

—

Návaznosti

I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Rok uplatnění

2019

Kód důvěrnosti údajů

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

Název periodika

Icarus

ISSN

0019-1035

e-ISSN

—

Svazek periodika

319

Číslo periodika v rámci svazku

2019

Stát vydavatele periodika

US - Spojené státy americké

Počet stran výsledku

9

Strana od-do

476-484

Kód UT WoS článku

000455422800032

EID výsledku v databázi Scopus

2-s2.0-85054729585