TY  - JOUR
A1  - Seiler, Michael
A1  - Seiß, Martin
A1  - Hoffmann, Holger
A1  - Spahn, Frank
T1  - Hydrodynamic Simulations of Asymmetric Propeller Structures in Saturn's Rings
JF  - The astrophysical journal : an international review of spectroscopy and astronomical physics ; Supplement series
N2  - The observation of the non-Keplerian behavior of propeller structures in Saturn's outer A ring raises the question: how does the propeller respond to the wandering of the central embedded moonlet? Here, we study numerically how the structural imprint of the propeller changes for a libration of the moonlet. It turns out that the libration induces an asymmetry in the propeller, which depends on the libration period and amplitude of the moonlet. Further, we study the dependence of the asymmetry on the libration period and amplitude for a moonlet with a 400 m Hill radius, which is located in the outer A ring. This allows us to apply our findings to the largest known propeller Blériot, which is expected to be of a similar size. For Blériot, we can conclude that, supposing the moonlet is librating with the largest observed period of 11.1 yr and an azimuthal amplitude of about 1845 km, a small asymmetry should be measurable but depends on the moonlet's libration phase at the observation time. The longitude residuals of other trans-Encke propellers (e.g., Earhart) show amplitudes similar to Blériot, which might allow us to observe larger asymmetries due to their smaller azimuthal extent, allowing us to scan the whole gap structure for asymmetries in one observation. Although the librational model of the moonlet is a simplification, our results are a first step toward the development of a consistent model for the description of the formation of asymmetric propellers caused by a freely moving moonlet.
KW  - Hydrodynamics
KW  - methods: data analysis
KW  - methods: numerical
KW  - planets and satellites: dynamical evolution and stability
KW  - planets and satellites: individual (Saturn)
KW  - planets and satellites: rings
Y1  - 2019
U6  - https://doi.org/10.3847/1538-4365/ab26b0
SN  - 0067-0049
SN  - 1538-4365
VL  - 243
IS  - 2
PB  - IOP Publ. Ltd.
CY  - Bristol
ER  - 
TY  - JOUR
A1  - Seiler, Martin
A1  - Sremcevic, Miodrag
A1  - Seiss, Martin
A1  - Hoffmann, Holger
A1  - Spahn, Frank
T1  - A Librational Model for the Propeller Bleriot in the Saturnian Ring System
JF  - The astrophysical journal : an international review of spectroscopy and astronomical physics ; Part 2, Letters
KW  - planets and satellites: individual (Saturn)
KW  - planets and satellites: rings
Y1  - 2017
U6  - https://doi.org/10.3847/2041-8213/aa6d73
SN  - 2041-8205
SN  - 2041-8213
VL  - 840
PB  - IOP Publ. Ltd.
CY  - Bristol
ER  - 
TY  - JOUR
A1  - Hoffmann, H.
A1  - Seiß, Martin
A1  - Spahn, Frank
T1  - Vertical relaxation of a moonlet propeller in Saturn's a ring
JF  - The astrophysical journal : an international review of spectroscopy and astronomical physics ; Part 2, Letters
N2  - Two images, taken by the Cassini spacecraft near Saturn's equinox in 2009 August, show the Earhart propeller casting a 350 km long shadow, offering the opportunity to watch how the ring height, excited by the propeller moonlet, relaxes to an equilibrium state. From the shape of the shadow cast and a model of the azimuthal propeller height relaxation, we determine the exponential cooling constant of this process to be lambda = 0.07 +/- 0.02 km(-1), and thereby determine the collision frequency of the ring particles in the vertically excited region of the propeller to be omega(c)/Omega = 0.9 +/- 0.2.
KW  - planets and satellites: individual (Saturn)
KW  - planets and satellites: rings
Y1  - 2013
U6  - https://doi.org/10.1088/2041-8205/765/1/L4
SN  - 2041-8205
VL  - 765
IS  - 1
PB  - IOP Publ. Ltd.
CY  - Bristol
ER  -