Sun and stars: astro-factories of chemical elements

Talk: 25th January 2024, 19:00, Conference Hall/Library of Alovera. Zoom

It is commonly said that we are all made of stardust... but what does this exactly mean? At the earliest stage of the big-bang, only some of the lighter chemical elements were synthesized: primarily hydrogen. It had to pass some time until gravity begun to form agglomerated regions of this lighter elements that grew up in mass until gravity compression initiated the fusion reaction, giving birth to the first stars in the universe. Elements up to iron are synthesized inside stars through fusion reaction chains. Life cycle of stars ends with violent events such as supernovae, that disperse all these elements throughout space. Again, nuclear processes allow synthesis of other chemical elements beyond iron. And gravity, again, agglomerates the debris into acretion disks where eventually a new star can be born, together with planetary systems and, in the end, life. That is why it is often said that we are stardust: the chemical elements we are made of are the consequence of the passage through "life" of stars that existed and died. In this talk we will explain some details of big-bang, primordial nucleosynthesis, fusion and nuclear chains and the life and death of stars. The classification of the stars will be given and we will explain how can we get all this information from so far away. We will also go into details about the closest star we know, our Sun: its physical characteristics, structure and dynamics.

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