Warm-Up What are the three characteristics that scientists use to categorize stars? – Hint: Look at your HR Diagrams from last week Time’s Up!

Life Cycle of a Star -- Video universe/videos/the-universe-life-and-death- of-a-star universe/videos/the-universe-life-and-death- of-a-star – 0-9:17

Star Death

Gravity pulls. Fusion begins. Fuel runs out. Gravity wins. Remember—the story for all stars…

Stellar Evolution of a low-mass star (0.08 to 0.8 solar masses): Low-density nebula H Protostar H Core is getting hotter million K in the core “Red dwarf” ZAMS H to He fusion in the core

The star’s main sequence goes on… and on…

Finally, H fuel in the core runs out Core collapses & heats, but never gets hot enough to fuse He Main sequence can last over 100 billion years White dwarf Black dwarf With fusion ceased, it gradually becomes cold and dark

Stellar Evolution of a medium-mass star (like the Sun) (0.8 to 8 solar masses): Medium - density nebula H Protostar H Core is getting hotter million K in the core ZAMS H to He fusion in the core Main sequence lasts about 10 billion years

H fuel in the core runs out White dwarf Black dwarf He - C H - He When fusion of He into C begins, the star swells up into a Red Giant Core collapses & gets hot enough to fuse He into C 100 million K in the core Core collapses but never gets hot enough to fuse C. The collapsed core becomes a white dwarf. The rest of the star drifts away as a planetary nebula. He fuel in the core runs out

Stellar Evolution of a high-mass star (>8 solar masses): High -density nebula H Protostar H Core is getting hotter million K in the core ZAMS H to He fusion in the core Main sequence lasts less than 2 billion years

H fuel in the core runs out He - C H - He When fusion of He into C begins, the star swells up into a Red Supergiant Core collapses & gets hot enough to fuse He into C 100 million K in the core C – N&O Fe 1.He fuel in the core runs out 2.Core collapses and gets hot enough to fuse C into N & O 3.C fuel in the core runs out 4.Core collapses and gets hot enough to fuse N & O into Fe 5.When formation of Fe begins in the core, fusion reaches a dead end

Iron kills fusion in the core. The core collapses, and the star explodes as a Supernova. Black hole Neutron Star If the core is >4 solar masses If the core is 1.5 to 4 solar masses

Supernova explosions produce so much energy that the star can briefly become brighter than the entire galaxy! Supernova

Life Cycle of a Star -- Death Evidence of Black Holes! Supermassive Black Hole in the center of the Milky WayMilky Way

Supergiant Star

Life Cycle of a Star -- Video universe/videos/the-universe-life-and-death- of-a-star universe/videos/the-universe-life-and-death- of-a-star – 9:17-19:00

OUT Write a story of a star from BIRTH to DEATH – Your story must include the following terms: Nebula Main Sequence Nuclear Fusion – Awesome Points will be given for creativity and a theatrical death!