Seminars
Our seminars take place in the lecture room of the building at
Praha–Sporilov.
Next seminar:
12.03.2018 14:00
James Fuller
Kavli Institute for Theoretical Physics, Caltech
Saturn Ring Seismology: Complex Interactions Between the Planet, the Rings, and the Moons
Abstract
James Fuller
Saturn Ring Seismology: Complex Interactions Between the Planet, the Rings, and the Moons
The rich dynamics of the Saturn ring and moon systems offer unique opportunities to study the evolution of the planet and its surrounding bodies. For instance, seismology of Saturn is made possible by the gravitational interaction between Saturn and its rings, in which density waves in the rings are excited at Lindblad resonances with Saturn's oscillation modes. The seismic signatures in the rings suggest the existence of stable stratification in the deep interior of the planet, likely created by composition gradients between the core and envelope due to helium sedimentation and/or core erosion. These structures within the planet influence the tidal interactions which drive the outward migration of Saturn's inner satellites. Rapid migration can occur when moons become locked in resonance with Saturn's oscillation modes, driving the moons outward on a planetary evolution timescale.
Previous seminar:
26.02.2018 14:00
Joerg Dabringhausen
Astronomical Institute of the Charles University, Prague
The curiously high mass-to-light ratios of ultra-compact dwarf galaxies
Abstract
Joerg Dabringhausen
The curiously high mass-to-light ratios of ultra-compact dwarf galaxies
While ultra-compact dwarf galaxies (UCDs) might just be the most massive globular clusters (GCs), they have also a few properties other than their mass and luminosity that set them apart from more conventional GCs. Among these are their dynamical mass-to-light ratios, which are rather high, and seem in fact inconsistent with the premise of a non-varying stellar initial mass-function (IMF). It was therefore proposed that the IMF in UCDs is top-heavy. I will discuss how this hypothesis relates to the high mass-to-light ratios of UCDs, their populations of neutron stars, and the possible presence of super-massive black holes in them.
If you would like to give a seminar in our group, please contact Petra Sukova or Vladimir Karas.
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