Cosmic explosions: A story about paradigms lost

Speaker:Hagai Perets
Location:Lidow Rosen Auditorium (323)

The wide diversity of cosmic explosion arise from a variety of complex 
physical phenomena.  Each one of these cosmic fireworks, be it 
supernovae, gamma ray burst, stellar collisions or tidal disruptions 
is different in nature, but many of them also share many similarities. 
In recent years the field of cosmic explosions began to be filled with 
a zoo of peculiar explosions ranging in orders of magnitude in 
brightness and time-length. I will discuss the strongly debated 
progenitors of such cosmic explosions, the main processes involved in 
their actual production, their major implications for the evolution of 
the universe, and I will touch upon the many open questions which they 
raise. In particular I will explain how do the regular seemingly 
delicate but shining life of stars eventually lead to their violent 
explosive death;  how close symbiotic relations between companion 
stars which exchange materials between them end up in a blasting 
breakout of a ball of fire.
If time permit, I will explore the realm of stellar dynamics where 
stars can clash and collide in small chaotic systems and in dense 
stellar clusters, and explain how lighter stars are shredded by more 
massive ones, or even by monstrous supermassive black holes in 
galactic nuclei.
Beside their magnificent role in lighting up our night sky, cosmic 
explosions have major implications for the overall evolution of the 
universe and our understanding of it, and play a key-role in the 
build-up of the basic elements needed for life. I will briefly discuss 
how they shape the environments of galaxies through a network of 
feedback processes between star formation and stellar death, and I'll 
review how explosive thermonuclear burning in these explosion 
synthesize the heavy elements which compose most of Earth and  and 
thriving living environment in which we live today.