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

Title: MIGRATION OF SMALL MOONS IN SATURN's RINGS

Abstract

The motions of small moons through Saturn's rings provide excellent tests of radial migration models. In theory, torque exchange between these moons and ring particles leads to radial drift. We predict that moons with Hill radii r {sub H} {approx} 2-24 km should migrate through the A ring in 1000 yr. In this size range, moons orbiting in an empty gap or in a full ring eventually migrate at the same rate. Smaller moons or moonlets-such as the propellers-are trapped by diffusion of disk material into corotating orbits, creating inertial drag. Larger moons-such as Pan or Atlas-do not migrate because of their own inertia. Fast migration of 2-24 km moons should eliminate intermediate-size bodies from the A ring and may be responsible for the observed large-radius cutoff of r {sub H} {approx} 1-2 km in the size distribution of the A ring's propeller moonlets. Although the presence of Daphnis (r {sub H} Almost-Equal-To 5 km) inside the Keeler gap challenges this scenario, numerical simulations demonstrate that orbital resonances and stirring by distant, larger moons (e.g., Mimas) may be important factors. For Daphnis, stirring by distant moons seems the most promising mechanism to halt fast migration. Alternatively, Daphnis may be amore » recent addition to the ring that is settling into a low inclination orbit in {approx}10{sup 3} yr prior to a phase of rapid migration. We provide predictions of observational constraints required to discriminate among possible scenarios for Daphnis.« less

Authors:
 [1]
  1. Department of Physics and Astronomy, University of Utah, 115 S 1400 E, Rm 201, Salt Lake City, UT 84112 (United States)
Publication Date:
OSTI Identifier:
22167684
Resource Type:
Journal Article
Journal Name:
Astrophysical Journal
Additional Journal Information:
Journal Volume: 764; Journal Issue: 2; 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; ASTRONOMY; ASTROPHYSICS; COMPUTERIZED SIMULATION; DIFFUSION; INCLINATION; MOMENT OF INERTIA; ORBITS; PARTICLES; RINGS; SATELLITES; SATURN PLANET; TORQUE

Citation Formats

Bromley, Benjamin C., and Kenyon, Scott J., E-mail: bromley@physics.utah.edu, E-mail: skenyon@cfa.harvard.edu. MIGRATION OF SMALL MOONS IN SATURN's RINGS. United States: N. p., 2013. Web. doi:10.1088/0004-637X/764/2/192.
Bromley, Benjamin C., & Kenyon, Scott J., E-mail: bromley@physics.utah.edu, E-mail: skenyon@cfa.harvard.edu. MIGRATION OF SMALL MOONS IN SATURN's RINGS. United States. https://doi.org/10.1088/0004-637X/764/2/192
Bromley, Benjamin C., and Kenyon, Scott J., E-mail: bromley@physics.utah.edu, E-mail: skenyon@cfa.harvard.edu. 2013. "MIGRATION OF SMALL MOONS IN SATURN's RINGS". United States. https://doi.org/10.1088/0004-637X/764/2/192.
@article{osti_22167684,
title = {MIGRATION OF SMALL MOONS IN SATURN's RINGS},
author = {Bromley, Benjamin C. and Kenyon, Scott J., E-mail: bromley@physics.utah.edu, E-mail: skenyon@cfa.harvard.edu},
abstractNote = {The motions of small moons through Saturn's rings provide excellent tests of radial migration models. In theory, torque exchange between these moons and ring particles leads to radial drift. We predict that moons with Hill radii r {sub H} {approx} 2-24 km should migrate through the A ring in 1000 yr. In this size range, moons orbiting in an empty gap or in a full ring eventually migrate at the same rate. Smaller moons or moonlets-such as the propellers-are trapped by diffusion of disk material into corotating orbits, creating inertial drag. Larger moons-such as Pan or Atlas-do not migrate because of their own inertia. Fast migration of 2-24 km moons should eliminate intermediate-size bodies from the A ring and may be responsible for the observed large-radius cutoff of r {sub H} {approx} 1-2 km in the size distribution of the A ring's propeller moonlets. Although the presence of Daphnis (r {sub H} Almost-Equal-To 5 km) inside the Keeler gap challenges this scenario, numerical simulations demonstrate that orbital resonances and stirring by distant, larger moons (e.g., Mimas) may be important factors. For Daphnis, stirring by distant moons seems the most promising mechanism to halt fast migration. Alternatively, Daphnis may be a recent addition to the ring that is settling into a low inclination orbit in {approx}10{sup 3} yr prior to a phase of rapid migration. We provide predictions of observational constraints required to discriminate among possible scenarios for Daphnis.},
doi = {10.1088/0004-637X/764/2/192},
url = {https://www.osti.gov/biblio/22167684}, journal = {Astrophysical Journal},
issn = {0004-637X},
number = 2,
volume = 764,
place = {United States},
year = {Wed Feb 20 00:00:00 EST 2013},
month = {Wed Feb 20 00:00:00 EST 2013}
}