Docentship lecture: How to kill a Red Giant?

Chairperson: Professor Nikolai Piskunov

Representative of the Docentship Committee: Professor Stephan Pomp

Abstract:

The twinkling stars seen in the night sky are not static objects, but form with different stellar masses and evolve over time. Most stars in the Mily Way are low mass stars that burn nuclear fuel at a slow rate and evolve on timescales of billions of years. Our Sun is an example of such a low mass star, and it will eventually exhaust the fuel in its core and instead burn fuel in shells around the dormant core. This shell burning will cause the future Sun to swell, about to the size of Earth's orbit, and turn it into a Red Giant star. The fate of a Red Giant is not decided by how fast it is burning its nuclear fuel, but rather by the heavy mass loss, through stellar winds, during this evolutionary phase. These stellar winds deliver elements synthesized in the interior of the stars, into the surrounding interstellar medium. The winds of Red Giants are therefore an important piece in the puzzle of the cosmic matter cycle, i.e., how elements are produced and accumulated in stars and planets as the Universe evolves from the elemental composition of the Big Bang nucleosynthesis. This lecture gives an introduction how stars evolve into Red Giant stars, their properties and structure and how the stellar winds that eventually cause their demise are driven. The effects of metal-poor environments on the mass-loss of these stars will also be discussed.

The lecture is an obligatory teaching test for those applying for admittance as docent and it should be possible for students and others with basic academic education in the relevant field to follow it. The lecture will last for 40-45 minutes and afterwards the audience may ask questions. The lecture will be given in Swedish.

Welcome!