Prescriptions for convection in 2D (axisymmetric) stellar models

By Pierre Lesaffre (ENS)

Room D18 (2nd floor) at ENS, 24 rue Lhomond, 13:00 to 13:45

Modeling a high velocity LMC: The formation of the Magellanic Stream

By Chiara Mastropietro (Observatoire de Paris)

Room D18 (2nd floor) at ENS, 24 rue Lhomond, 13:00 to 13:45

 

I use high resolution N-body/SPH simulations to model the new proper motion of the Large Magellanic Cloud (LMC) within the Milky Way (MW) halo and investigate the effects of gravitational and hydrodynamical forces on the formation of the Magellanic Stream (MS). Both the LMC and the MW are fully self consistent galaxy models embedded in extended cuspy LCDM dark matter halos. I find that ram-pressure from a low density ionized halo is sufficient to remove a large amount of gas from the satellite's disk forming a trailing Stream that extends more than 120 degree from the Cloud. The morphology of the Stream is used to test different density profiles of the hot gaseous halo surrounding the MW. Tidal forces elongate the LMC's disk but do not affect its vertical structure. No stars become unbound showing that tidal stripping is almost effectiveless.

Simulations of fine-scale structure in Saturn's rings

By Henrik Latter (LRA, ENS)

Room D18 (2nd floor) at ENS, 24 rue Lhomond, 13:00 to 13:30

Recent radio and UV occultation experiments carried out by the Cassini spacecraft have revealed that swathes of Saturn's A and B-ring support fine-scale axisymmetric patterns. This 'microstructure' is surprisingly regular, possessing wavelengths between 150 and 250 metres, and is probably driven by a pulsational instability of viscous origin. Using a simple hydrodynamical model, I show how this fine-scale quasiperiodic structure is generated by the instability, and how it may relate to irregular features on slightly larger-scales.