Chapter 8 Lesson 4- Stars and the Universe
Vocabulary
1. Star
2. Nebula
3. White dwarf
4. Supernova
5. Black hole
6. Constellation
7. Light-year
8. Galaxy
NOTES
How do stars form?
· Stars form when matter comes together and starts to give off energy.
· Stars go through stages and different stars go through different stages.
· The cycle of a star depends on how much hydrogen the star contains.
· A stars cycle ends when it stops giving off energy.
· All stars form from a nebula.
· Gravity pulls the mass off the nebula together.
· As they get closer together they collide with each other.
· Collisions produce heat and the temperature to rise.
· Protostar – beginning star.
· Hydrogen is the fuel that produces energy in the sun.
· Red giant many times larger than a normal star.
· Helium atoms started forming carbon.
· Eventually the helium begins to cool down and can’t make carbon.
· The star shrinks and becomes a white dwarf.
· This is the end of the medium sized star cycle.
What happens to larger stars?
· Supernovas shine brightly for days or weeks and then fade away.
· A supernova will form a new nebula.
· Stars are characterized by their color and temperature.
· Red and Orange= cooler Yellow=Middle White and Blue=Hotter
· Giant stars have diameters that are 10 to 100 times of the sun.
· Giant Stars-10-100
· Super Giants-1000
· Neutron stars- smallest
· Gravitational Microlensing- analyzing data of the stars brightness for changes that show that a planet passed in front of a star.
What are constellations?
· Constellations are named after animals, characters in stories, and familiar objects.
· Constellations help us with directions.
· Polaris-north star
· If you are lost in the woods, look for Polaris it will guide you to safety.
· Next closest star to earth is Proxima Centauri, 40 trillion, 4.2 light years, away.
What are star systems?
· Each galaxy holds millions of stars.
· The basic shapes are spiral, elliptical, and irregular.
· Our solar system is located in the Milky Way galaxy.
· The Milky Way is a spiral galaxy.
· Bared spirals galaxies have 2 arms that spread across.
· Elliptical galaxies are round and look like a think pancake.
· Irregular galaxies have no definite shape.
· Clusters are shaped like a sphere and hold a 100,000 or more stars.
· Binary stars- when 2 stars form near each other and around each other.
How did the universe form?
· The Big Bang Theory- the universe started out as a big bang and has been expanding ever since.