Moonlets in planetaren Ringen: Implikationen für die Ringentstehung?

• Antragsteller: Professor Frank Spahn, Ph.D.
• Fachliche Zuordnung: Astrophysik und Astronomie
• Förderung: Förderung von 2005 bis 2012
• Projektkennung: Deutsche Forschungsgemeinschaft (DFG) - Projektnummer 5445455

• Erstellungsjahr: 2012

Zusammenfassung der Projektergebnisse

In course of the project our early models of the gravitational action of small moons (moonlets) embedded directly in dense planetary have been extended in order to complete the structural “fingerprint” of such moonlets. Numerical particle-in-a-box “experiments” considering dissipative particle collisions and full three spatial dimensions have been carried out to show that the predicted propeller structures are decorated with density wakes which strongly modify the appearance of the structure. Furthermore, the radial and azimuthal scalings, obtained analytically, have been confirmed with the numerical simulations so that in this way indeed a model “characteristics” pointing to embedded moonlets has been provided in the framework of the project. This theoretical preliminary has been affirmed by the detection of the predicted Propellerstructures by Tiscareno et al. Motivated by these successes, we (former and present members of our group) have inspected further data of the cameras (ISS) of the Cassini spacecraft with the result of spotting eight moonlets out of 13 Propellers. Five images show a reappearance of the feature at a later moment shifted by the orbital motion proving in this way that these structures are indeed grooved in the rings by the gravity of “skyscraper”-sized moonlets! Meanwhile more than 150 Propellermoonlets have been detected in the A ring (and a few even in the B ring) of Saturn.

Projektbezogene Publikationen (Auswahl)

• (2005). Structures induced by small moonlets in Saturn’s rings: Implications for the Cassini mission. Geophys. Res. Lett., 32
  Seiß, M.; Spahn, F.; Sremčevič, M.; and Salo, H.
  
• (2006). Cassini dust measurements at Enceladus: Implications for Saturn’s E ring. Science, 311:1416–1418
  Spahn, F.; Seiß, M. et al.
  
• (2006). E ring dust sources: Implications from Cassini’s dust measurements. Planet. Space Sci., 54:1024–1032
  Spahn, F.; Albers, N.; Hörning, M.; Kempf, S.; Krivov, A.; Makuch, M.; Schmidt, J.; and Seiß, M.
  
• (2006). Saturn’s bared Mini-Moons. Nature, 440:614–615
  Spahn, F. and Schmidt, J.
  
• (2007). A belt of moonlets in Saturn’s A ring. Nature, 449:1019–1021
  Sremčevič, M.; Schmidt, J.; Salo, H.; Seiß, M. ; Spahn, F.; and Albers, N.
  
• (2008). The dust halo of Saturn’s largest icy moon, Rhea. Science, 319:1380 – 1384
  Jones, G. H.; Seiß, M.; Spahn, F. et al.
  
• (2010). Moonlet induced wakes in planetary rings: Analytical model including eccentric orbits of moon and ring particles. Icarus, 210:298–317
  Seiß, M.; Spahn, F.; and Schmidt, J.
  
• (2011). Hydrodynamics of Saturn’s dense rings. Math. Model. Nat. Phenom., 4:191–218
  Seiß, M. and Spahn, F.