1. Test Prompt 1.As a star runs out of nuclear energy, what do you think will occur to the size of the star? Provide an explanation as to why you think that. Jan 23

2. News/Updates Wednesday – Life and Death of a Star – VERY IMPORTANT (we’ll review today) Thursday – Hubble’s Constant activity – LESS IMPORTANT (we’ll review on today/Monday)

3. Today’s Date Opening Activity Work Today’s Picture(s) Exit Slip Today’s Note(s) Protostar Death of HM Death of LM Giants Intro Your Own Model Nebula 3 Types Main Sequence Main Sequence Death of MM Blackhole Star Forces Exit Activity

4. Star Cycle There are 6 primary steps in the life and death of stars.

5. Nebula Cloud The nursery of stars. This “ cloud ” is a combination of Hydrogen, gas, and dust (remnants of other stars and objects of the universe). The matter used to make stars are recycled from other substances in the universe.

7. Protostar The beginning of a star. The nebula cloud condenses due to gravity and forms a solid body. The condensing of matter releases energy, the protostar is the first stage in which light is emitted. Nebula

8. Depending on the amount of matter in the nebula cloud, stars will either become low, medium or high mass stars. ALL of the stars create Helium from fusing together two Hydrogen nuclei. Protostar Low Mass Stars Makes Helium only High Mass Stars Makes Helium - Iron Med Mass Stars Makes Helium - Carbon

9. Death of Low Mass Stars When running out of fuel, low mass stars will simply collapse and die out.

10. Medium Mass Stars The main life of a medium mass stars is known as “main sequence stars” There are different types of main sequence stars depending on the size/mass/ temperature/ luminescence/ etc. Our sun is a “G” main sequence star (all other stars in the universe are compared to our sun).

11. Medium mass stars turn into Red Giants High mass stars turn into Super Red Giants When running out of fuel, medium and high mass stars will expand into red giants and super red giants. High Mass Med Mass Super Red Giants Fuses to make Iron Red Giants Fuses to make Carbon

12. Death of Medium Mass Stars When fuel is completely gone, the medium mass stars will shrink on their own gravity. Red giants will turn into dwarf stars depending on the amount of energy left (red dwarf, white dwarf, brown dwarf, etc.) Red Giant Dwarf Stars

13. Death of High Mass Stars Supernovas Depending on the amount of mass/energy, the stars can explode. High Mass stars often times explode! This spreads all of the elements Hydrogen through Iron (which makes up our planets and other new stars) and forms all elements after Iron (up to element 92- Uranium). Super Red Giants Supernova

14. Blackhole Blackholes are the result of dwarf stars that collapse on themselves. The stars have run out of fuel (so no light is emitted), therefore it looks dark/black. But still has a lot of gravity/mass in a little spot (about the size of a small town) Dwarf Stars Black Hole

15. Forces of a Star Thermal Expansion vs Gravity As a star fuses Hydrogen into Helium and into other elements, this creates a release of energy and therefore increased radiation pressure that is called thermal expansion. As the core runs out of energy, the star begins to expand and near the end of it’s life will either collapse into a dwarf due to gravity, or will supernova due to an increase in thermal pressure.

16. Exit Activity On the back of your graphic organizer/note handout, there is an essential question regarding the energy of a star and the lifetime of the star. Create a hypothesis to the question, then look at the data provided to pull out specific evidence, write a justification of why you pulled that evidence, then write a claim.

17. Exit Slip Look at the graph/image on the next slide: What is the relationship between the following variables compared to size (radius): As mass INCREASES Temperature______________ Radius______________ Luminosity______________ Lifetime______________ Abundance______________