Name: ____________________________ Date: ___________________ Per: ___ Astronomy: Stars Notes Outline Which star is closest to our sun? In which star system is it? What is the definition of a light year, and what distance is it in kilometers? How long does it take for light from the sun to reach the edge of our solar system? _______________ What is the distance in light years and kilometers for each of the following? Proxima Centauri ___________________ ly ________________ km Center to edge of Milky Way ___________________ly ________________km What is parallax? In general, how is parallax used to measure distances to stars? What three factors are used to classify stars? How are the colors and temperatures of stars related? Which stars are hotter? Cooler? What is a star’s apparent brightness? What 2 factors influence apparent brightness? What is a star’s absolute brightness? How does it differ from apparent brightness? How is a spectrometer used to determine a star’s composition? What 2 elements make up over 95% of a star’s mass? ___________________ and __________________ What is a Hertzsprung-Russell diagram? What important information can it provide about a star? What are Main Sequence stars and what are their characteristics? What are Giants and Supergiants? What are white dwarfs? How does star form from a nebula? What is hydrostatic equilibrium? Why do high-mass stars have shorter life spans than low-mass stars? How does a star become a red giant? What happens between a star’s red giant phases? What element provides the fuel for nuclear fusion? Explain how a star can have more than one red giant phase. What types of star clusters are there and how do they differ? How do we know that the universe is expanding? .