ESU06 - Stars Understands the role of gravity in forming and maintaining planets, stars, and the solar system Learning Targets: Knows the terms nuclear fusion, nova, supernova, black hole, neutron star, and nebula Knows the basic structure and composition of a star Knows the life cycle of a star

Stars – Facts Can’t even estimate how many there are 100 Billion galaxies each with 100 B stars We can see ≈ 3000 People have always navigated by stars Some stars are named Different stars do have different colors, brightness and sizes

Some stars are binary stars and revolve around each other Stars – Facts binary means … … two Some stars are binary stars and revolve around each other

Stars – Facts Officially there are … … 88 technically Big Dipper is an asterism (not official) Constellation – a formation of stars that looks like a figure or design

Structure of a Star – Interior Core – 15 Million degrees C Made of gasses (H & He) This is where fusion happens Convection Zone – Circulates hot gasses

Structure of a Star – Interior 2 3 Core – 15 Million degrees C 1 Made of gasses (H & He) This is where fusion happens Convection Zone – Circulates hot gasses 4 8 5 7 6

Structure of a Star – Surface Chromosphere – Bottom layer of the surface 5500 degrees C Corona – Next layer away from the core. 2 Million degrees C What we see during eclipse Prominence – gasses that kind of burp out of the sun Solar Flare – gasses that blast out of the sun Sun spots – go along with Pr & SF cooler Solar Wind – sent out from flares, plasma, disrupts wx/electronics

Life Cycle of a Star - Birth Large cloud of gas/ice/dust (nebula) Also known as the “star nursery” This material condenses (protostar) 1 million K Fusion H  He star 10 million K

Life Cycle of a Star - Life Gravity keeps pulling material in Fusion, which releases energy, keeps pushing out equilibrium is reached At equilibrium stars are Main Sequence Stars Stars spend most of their life as Main Sequence Stars

Life Cycle of a Star - Life Star will last as long as there is H to burn Higher the temperature of a star the brighter 90% of stars, including our sun, are main sequence stars

Life Cycle of a Star Yeah, that’s all cool Mr Dalton but we can we do something more exciting? Sure Lacy, how bout a video?

Review 1. What is the scientific word for a “star nursery”? 2. What material begins a star? 3. What happens to that material? 4. What is a “baby star” called? 5. What temperature is needed for it to become a star?

Review 6. Gravity pulls in, what pushes out? 7. What do we call it when the force pulling in matches the force pushing out? 8. Where on the H-R diagram do stars spend most of their life? 9. How long will a star last? 10. Is a bright star hotter or cooler?

Death - Average Size Star runs out of H  no more pushing out More stuff in – temp goes up  Helium burns Now it is a giant Main Sequence  Giant  White Dwarf  Nova He  C 100 M K Now becomes a white dwarf (Dead) Novas (explosions of H & He) will appear from time to time

Death - Large Size Same as with an average size star Hydrogen (H) burns  Helium (He) burns  Carbon  …Iron Now it is a supergiant Main Sequence  Supergiant  Neutron Star Sends heavy elements into space Neutron Star (Dead) He  Fe 10 Billion Kelvin More mass Explodes Supernova

Death – Very Large Size Same as with an average (and large) size star Hydrogen (H) burns  Helium (He) burns  Carbon  …Iron Now it is a supergiant Main Sequence  Supergiant  Black Hole Sends heavy elements into space Black Hole He  Fe 100 B K More mass Explodes Supernova

Life Cycle of a Star Can we watch another video, and can this one have cool music? Sure George

Do Stars Move?

Concept Map What do we call a “baby” star? Nebula What gives birth to a star? If it is a lg or very lg size star what do we call it? If it is an average size star what do we call it? Protostar Lg/Very Lg Average Supergiant Red Giant What will happen when it burns through iron? What will it be when it dies? Supernova Very Large White Dwarf Large? Neutron Star may see Black Hole Nova

Concept Map What do we call a “baby” star? What gives birth to a star? If it is a lg or very lg size star what do we call it? If it is an average size star what do we call it? Lg/Very Lg Average What will happen when it burns through iron? What will it be when it dies? Very Large Large? may see