Fr. 12. September 2014

Fat man, the nuclear bomb which was detonated over Nagasaki on 9 August 1945, released an energy of 21 kilotons - for number lovers this is 88000000000000 or 8.8x1013 Joules in physical units. Mankind unfortunately produced much more powerful bombs. The Tsar bomba, the the most powerful nuclear weapon ever detonated, was 2400 times more powerful than fat man. This is a colossal and incredibly disruptive explosion for Earth's standards but cosmic explosions are unimaginably more powerful. In particular, this seminar will be mostly devoted to the so-called Supernova explosions, which are able to tear a whole massive star apart. Again, for number lovers, a typical Supernova explosion is 100000000000000000000000000 or 1027 times more powerful than the Tsar bomba! Clearly, these events, able to briefly outshine a whole galaxy, produce serious damages in a galaxy and the damages are larger for smaller and less resilient galaxies (the so-called dwarf galaxies). I will review what is known about supernova explosions in different types of galaxies (with an emphasis on explosions in dwarf galaxies) and the (serious!) consequences of these explosions for the dynamical and chemical evolution of these objects. To finish, I will explain the link between Supernova explosions and one of the most spectacular event in the life of some galaxies: galactic winds, namely, extremely high-speed (up to 100-200 km/s!) streams of gas and dust that are often observed blowing out of galaxies.