Presentation on theme: "By Danny, Tiffany, and Connor. A “star” is a massive, luminous ball of plasma held together by gravity. A star forms as a collapsing cloud of material."— Presentation transcript:
A “star” is a massive, luminous ball of plasma held together by gravity. A star forms as a collapsing cloud of material composed mainly of hydrogen, along with helium and trace amounts of heavier elements. Stars shine due to thermonuclear fusion. This is a process where hydrogen in the core of the star, releases energy that travels through the star and eventually radiates into space.
Most stars are between 1 billion and 10 billion years old. The more massive the star, the shorter its lifespan. This is because there is greater pressure in the star’s core. Red Dwarfs can have a lifespan of up to hundreds of billions of years.
Star Classification classified by their spectra (elements that they absorb) Temperature There are 7 types O, B, A, F, G, K & M O & B stars are uncommon but bright M stars are common but dim
The Hertzsprung -Russell (H-R) Diagram is a graph that plots stars color (spectral type or surface temperature) vs. its luminosity. On it, astronomers plot stars’ colors, temperature, luminosity and evolutionary stage
This diagram shows 3 different types of stars Main sequence stars Super Giants/Giants Dwarf stars
Young stars Fueled by nuclear fusion (converting hydrogen -> helium) 90% of stars are Main sequence stars The hotter the brighter Yellow dwarf & Red dwarf
A red giant is a relatively old star whose diameter is about 100 times bigger than it was originally. A blue giant is a huge, very hot, blue star. It is a post- main sequence star that burns helium. A supergiant is the largest known type of star; some are almost as large as our entire solar system.
Small faint stars A white dwarf is a small, very dense, hot star that is made mostly of carbon. Their nuclear cores are depleted. They are about the size of the Earth and will eventually become a black dwarf
A binary star is a system of two stars that rotate around a common center of mass (the barycenter). About half of all stars are in a group of at least two stars.
The closest star to the earth is the sun. The earth receives most of its energy from the sun. The sun in our solar system is approximately 4.5 billion years old.
"Stars." Imagine The Universe! Home Page. Web. 14 Mar. 2011.. "Stars." Universe Today. Web. 14 Mar. 2011.. "Stars, Constellations, Galaxies and Nebulae Facts." Kid's Cosmos-Science Resources for Teachers and Students. Web. 14 Mar. 2011..
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