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science last chapter


spectrograph a devise that breaks light into colors and produces an image of the resulting spectrum.
apparent brightness a star's brightness as seen from Earth. it's measured fairly easy using electronic devices.
absolute brightness brightness the star would have if it were at a standard distance from Earth. finding absolute brightness is more complex than finding its apparent brightness astronomers must first find out apparent brightness and distance from Earth to calculate it's ABSOLUTE brightness. can vary tremendously.
hertzsprung-russell diagram shows the relationship between the absolute brightness and surface temperature of the star
main sequence diagonal area on the H-R diagram where 90% of stars, including the sun, are located
why is it hard to prove black holes exist? you can't see them and no one has been in or out of one.
black hole an object with gravity so strong that light can't escape
how are starts classified? color, temperature and size
what does the color of a star reveal? it's temperature
what color are the coolest stars? red 3,200 C
what color are medium heat star? yellow 5,500 C
what color are the hottest stars? blue 20,000 C
size of stars varies. most are size of sun but some are giant or supergiant sized.
chemical composition of stars 73% hydrogen 25% helium 2% other elements
brightness of a star depends on it's size and temperature. hotter stars are brighter than cooler stars looks brighter when closer to Earth
Created by: gott