L1 Stellar Nucleosynthesis PDF

Physical Science Stelllar nucleosynthesis Prepared by: Ms. Janine D. Millar  Lesson Targets Explain stellar 01 nucleosynthesis Compare the two types of 02 star; average and massive star. Cite the different heavy 03 elements formed in each stages of star cycle ...

Physical Science Stelllar nucleosynthesis Prepared by: Ms. Janine D. Millar  Lesson Targets Explain stellar 01 nucleosynthesis Compare the two types of 02 star; average and massive star. Cite the different heavy 03 elements formed in each stages of star cycle  Introduction The world where we live today is just a small part of our universe.This lesson will focus on one of those wonderful things present in outer space, the stars. Although stars are millions of light years away from us, we can still see them twinkling in the night sky.  Check your prior knowledge Can you give one example of the theory suggesting the beginning of the universe?  big bang theory Scientists believe that the formation of the universe began through the explosion of a primordial atom which happened 13 billion years ago. It is known as the Big Bang. It became a theory that also explains the continuous expansion of the universe.  arrange the sequence of the big bang theory forms stars and Continuously galaxies expanding inflation singularity universe cooled down forms other matter recombination  The big bang theory singularity inflation universe recombination cooled down forms stars forms other and galaxies matter Continuously expanding  note Right after Big Bang, protons and neutrons combined together and formed light elements Hydrogen and Helium in the process of Big Bang Nucleosynthesis. Other light elements such as Lithium and Beryllium were also formed during this process.  definition of terms Atom- is the smallest unit of an ordinary matter that forms a chemical element. Isotopes- each of two or more of same element containing equal number of protons but different number of neutrons in their nuclei. Atomic number- number of protons in an element’s nuclei. Atomic mass- associated with the number of protons and neutrons that are present in a particular nucleus of an element.  question: How other light elements are formed?  Stellar nucleosynthesis The word “stellar” means star and the formation of elements in the center of the star is called stellar nucleosynthesis. During this Stellar evolution, nuclear reactions continued, which produced elements heavier than lithium/beryllium to iron.  RADIOACTIVE DECAY It is the process by which an unstable atomic nucleus loses energy by radiation. A material containing unstable nuclei is considered as radioactive. Three of the Most Common Types of Radioactive Decay: 1. Alpha decay (α) – alpha particle is emitted 2. Beta decay (β) 3. Gamma decay (γ) main sequence star The diagram shows the Proton-Proton Chain reaction in main sequence star. This is the process by which average star gets their energy and convert Hydrogen into Helium. massive star Case is different in massive star or star eight times larger than solar mass. They undergo CNO (Carbon, Nitrogen, Oxygen) cycle to convert Hydrogen into Helium. red giant star Tri alpha process happens in red giant star once they leave the stage of main sequence star. super red giant star A star accumulates more mass and continues to grow into red super giant. Alpha particle fusion happens at its core and creates more heavy elements until Iron. This is known as the Alpha ladder process.  additional: Neutron capture, a neutron is added to a seed nucleus. Below is the representation of how neutron is captured and heavier nucleus is formed. Two types of NEUTRON CAPTURE: S-process or slow process happens when there is a slow rate of capturing neutron while there is a faster rate of radioactive decay hence increasing the proton by 1.  additional: R-process or rapid process means that there is faster rate of capturing neutron before it undergoes radioactive decay thus, more neutrons can be combined at the nucleus. This is what happens in a supernova forming heavier elements than Iron with the process known as supernova nucleosynthesis. The explosion of star or supernova is believed to be the source of other elements heavier than Iron.  Thank you for listening!