Life and Death of a Star

Sources of Energy A Star has Two Sources of Energy Source 1: Fusion –The Conversion of Light Elements into Heavier Ones Source 2: Gravity –The attraction of each atom in the star to every other atom

Sources of Energy Fusion –The joining of Hydrogen Nuclei to make Helium –Can also join Helium Nuclei to make Beryllium –Attempts to Blow the Star apart –Happens only at the very Core of the Star

Sources of Energy Gravity –Draws all the matter of the Star inward –Is the weakest of all the fundamental forces –Grows in strength as the amount of matter increases or the size of the star shrinks

Life of a Star Main Phases of a Star’s Birth –Formation of Cloud Gathering of Innerstellar Dust Innerstellar means the stuff between Stars –Cloud to Protostar Formation of the Seed that will become a Star –Protostar to Star Heating up to full fledged Star

Life of a Star Stellar Cloud –Begins at a cool temperature of 10-30K –Planet Earth is Typically around 300K –Cloud begins to shrink and glow

Life of a Star Protostar –The Stellar Cloud collapses so much that the internal temperature and pressure rise dramatically –The Core begins to push back against Gravity and the Protostar is formed –The core is NOT yet hot enough for Fusion –However the seed of a new star is planted

Life of a Star Star –When the Internal Temperature reaches 10 million K, it is hot enough for Fusion to start –The Hydrogen burning star is born and maintains a balance between gravity and pressure –This balance is known as gravitational equilibrium –This is now a main sequence star

Mass of a Star Every Star in the Universe is compared to our Sun when we talk about mass Our Sun is designated as having 1 Solar Mass Thus a Star with 4 Solar Masses is 4 times bigger than our Sun Every Star has a specific Mass when it is born that will determine the Star’s eventual fate

Mass of a Star Birth Weights - there are 3 possible birth weights for a Star –Low Mass Star: Solar Masses –Intermediate Mass: Solar Masses –High Mass Star: 8 Solar Masses or Bigger The Fate of Each individual Star depends almost entirely on its Birth Mass

Size and Fate Bigger Stars form faster and burn hotter and brighter, but die Faster and more spectacularly Smaller Stars take longer form, burn cooler, but live much longer and have Simple Deaths Big Stars may only live for hundreds of Million of years Small Stars may live for Billions

Astronomy Assessment In class essay that will take place during your lab day Minimum of 3 paragraphs: Intro, Body and Conclusion Minimum of 1 hand written page or 300 words May bring in any notes to use during the essay writing

Essay Prompts Compare and Contrast the Life of a Star to the Life of a Human. Mention the Growth, Stages of Development, Life Expectancy, and Death of Each. Compare and Contrast the Formation, Life, Destruction and Recycling of Veterans Stadium to a Solar System Compare and Contrast the Big Bang to a Bag of Microwavable Popcorn. Relate the Formation, Expansion, Life Time, Collapse and Destruction of Each.