skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: STRONG TIDAL DISSIPATION IN SATURN AND CONSTRAINTS ON ENCELADUS' THERMAL STATE FROM ASTROMETRY

Abstract

Tidal interactions between Saturn and its satellites play a crucial role in both the orbital migration of the satellites and the heating of their interiors. Therefore, constraining the tidal dissipation of Saturn (here the ratio k{sub 2}/Q) opens the door to the past evolution of the whole system. If Saturn's tidal ratio can be determined at different frequencies, it may also be possible to constrain the giant planet's interior structure, which is still uncertain. Here, we try to determine Saturn's tidal ratio through its current effect on the orbits of the main moons, using astrometric data spanning more than a century. We find an intense tidal dissipation (k{sub 2}/Q = (2.3 {+-} 0.7) Multiplication-Sign 10{sup -4}), which is about 10 times higher than the usual value estimated from theoretical arguments. As a consequence, eccentricity equilibrium for Enceladus can now account for the huge heat emitted from Enceladus' south pole. Moreover, the measured k{sub 2}/Q is found to be poorly sensitive to the tidal frequency, on the short frequency interval considered. This suggests that Saturn's dissipation may not be controlled by turbulent friction in the fluid envelope as commonly believed. If correct, the large tidal expansion of the moon orbits duemore » to this strong Saturnian dissipation would be inconsistent with the moon formations 4.5 Byr ago above the synchronous orbit in the Saturnian subnebulae. But it would be compatible with a new model of satellite formation in which the Saturnian satellites formed possibly over a longer timescale at the outer edge of the main rings. In an attempt to take into account possible significant torques exerted by the rings on Mimas, we fitted a constant rate da/dt on Mimas' semi-major axis as well. We obtained an unexpected large acceleration related to a negative value of da/dt = -(15.7 {+-} 4.4) Multiplication-Sign 10{sup -15} AU day{sup -1}. Such acceleration is about an order of magnitude larger than the tidal deceleration rates observed for the other moons. If not coming from an astrometric artifact associated with the proximity of Saturn's halo, such orbital decay may have significant implications on the Saturn's rings.« less

Authors:
; ; ; ;  [1];  [2]; ;  [3];  [4];  [5];  [6]
  1. IMCCE-Observatoire de Paris, UMR 8028 du CNRS, UPMC, 77 Av. Denfert-Rochereau, 75014 Paris (France)
  2. Royal Observatory of Belgium, Avenue Circulaire 3, 1180 Uccle, Bruxelles (Belgium)
  3. Laboratoire AIM, CEA/DSM-CNRS-Universite Paris Diderot, IRFU/SAp Centre de Saclay, 91191 Gif-sur-Yvette (France)
  4. SyRTE-Observatoire de Paris, UMR 8630 du CNRS, 77 Av. Denfert-Rochereau, 75014 Paris (France)
  5. Laboratoire de Planetologie et Geodynamique de Nantes, Universite de Nantes, CNRS, UMR 6112, 2 rue de la Houssiniere, 44322 Nantes Cedex 3 (France)
  6. LUTH-Observatoire de Paris, UMR 8102 du CNRS, 5 place Jules Janssen, 92195 Meudon Cedex (France)
Publication Date:
OSTI Identifier:
22037107
Resource Type:
Journal Article
Journal Name:
Astrophysical Journal
Additional Journal Information:
Journal Volume: 752; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0004-637X
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ACCELERATION; ASTRONOMY; ASTROPHYSICS; EQUILIBRIUM; EVOLUTION; FRICTION; MECHANICS; MOON; ORBITS; SATURN PLANET; STABILITY

Citation Formats

Lainey, Valery, Desmars, Josselin, Arlot, Jean-Eudes, Emelyanov, Nicolai, Remus, Francoise, Karatekin, Oezguer, Charnoz, Sebastien, Mathis, Stephane, Le Poncin-Lafitte, Christophe, Tobie, Gabriel, and Zahn, Jean-Paul. STRONG TIDAL DISSIPATION IN SATURN AND CONSTRAINTS ON ENCELADUS' THERMAL STATE FROM ASTROMETRY. United States: N. p., 2012. Web. doi:10.1088/0004-637X/752/1/14.
Lainey, Valery, Desmars, Josselin, Arlot, Jean-Eudes, Emelyanov, Nicolai, Remus, Francoise, Karatekin, Oezguer, Charnoz, Sebastien, Mathis, Stephane, Le Poncin-Lafitte, Christophe, Tobie, Gabriel, & Zahn, Jean-Paul. STRONG TIDAL DISSIPATION IN SATURN AND CONSTRAINTS ON ENCELADUS' THERMAL STATE FROM ASTROMETRY. United States. https://doi.org/10.1088/0004-637X/752/1/14
Lainey, Valery, Desmars, Josselin, Arlot, Jean-Eudes, Emelyanov, Nicolai, Remus, Francoise, Karatekin, Oezguer, Charnoz, Sebastien, Mathis, Stephane, Le Poncin-Lafitte, Christophe, Tobie, Gabriel, and Zahn, Jean-Paul. 2012. "STRONG TIDAL DISSIPATION IN SATURN AND CONSTRAINTS ON ENCELADUS' THERMAL STATE FROM ASTROMETRY". United States. https://doi.org/10.1088/0004-637X/752/1/14.
@article{osti_22037107,
title = {STRONG TIDAL DISSIPATION IN SATURN AND CONSTRAINTS ON ENCELADUS' THERMAL STATE FROM ASTROMETRY},
author = {Lainey, Valery and Desmars, Josselin and Arlot, Jean-Eudes and Emelyanov, Nicolai and Remus, Francoise and Karatekin, Oezguer and Charnoz, Sebastien and Mathis, Stephane and Le Poncin-Lafitte, Christophe and Tobie, Gabriel and Zahn, Jean-Paul},
abstractNote = {Tidal interactions between Saturn and its satellites play a crucial role in both the orbital migration of the satellites and the heating of their interiors. Therefore, constraining the tidal dissipation of Saturn (here the ratio k{sub 2}/Q) opens the door to the past evolution of the whole system. If Saturn's tidal ratio can be determined at different frequencies, it may also be possible to constrain the giant planet's interior structure, which is still uncertain. Here, we try to determine Saturn's tidal ratio through its current effect on the orbits of the main moons, using astrometric data spanning more than a century. We find an intense tidal dissipation (k{sub 2}/Q = (2.3 {+-} 0.7) Multiplication-Sign 10{sup -4}), which is about 10 times higher than the usual value estimated from theoretical arguments. As a consequence, eccentricity equilibrium for Enceladus can now account for the huge heat emitted from Enceladus' south pole. Moreover, the measured k{sub 2}/Q is found to be poorly sensitive to the tidal frequency, on the short frequency interval considered. This suggests that Saturn's dissipation may not be controlled by turbulent friction in the fluid envelope as commonly believed. If correct, the large tidal expansion of the moon orbits due to this strong Saturnian dissipation would be inconsistent with the moon formations 4.5 Byr ago above the synchronous orbit in the Saturnian subnebulae. But it would be compatible with a new model of satellite formation in which the Saturnian satellites formed possibly over a longer timescale at the outer edge of the main rings. In an attempt to take into account possible significant torques exerted by the rings on Mimas, we fitted a constant rate da/dt on Mimas' semi-major axis as well. We obtained an unexpected large acceleration related to a negative value of da/dt = -(15.7 {+-} 4.4) Multiplication-Sign 10{sup -15} AU day{sup -1}. Such acceleration is about an order of magnitude larger than the tidal deceleration rates observed for the other moons. If not coming from an astrometric artifact associated with the proximity of Saturn's halo, such orbital decay may have significant implications on the Saturn's rings.},
doi = {10.1088/0004-637X/752/1/14},
url = {https://www.osti.gov/biblio/22037107}, journal = {Astrophysical Journal},
issn = {0004-637X},
number = 1,
volume = 752,
place = {United States},
year = {Sun Jun 10 00:00:00 EDT 2012},
month = {Sun Jun 10 00:00:00 EDT 2012}
}