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Download Characteristics of Stars Stars Analyzing Starlight Star Characteristics
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30.1 Characteristics of Stars Characteristics of Stars Section 30.1 Analyzing Starlight · spectrographs - device that separates light into different wavelengths (colors) · each star produces a unique spectrum (series of colors and lines) · a star's spectrum tells us elements present (composition) surface temperature how fast the star is moving toward or away from Earth Stars · star = ball of gas that emits light · fueled by nuclear fusion · vary in color Star Characteristics · composition most common element - hydrogen second most common - helium · temperature blue = hottest yellow (ex. sun) red = coolest · size and mass dwarf, medium, and giant Solar spectrum 1 How do scientists determine the composition and temperature of stars? A by taking samples from the star's surface B by analyzing the vibrations that the star emits C through magnetic testing D by analyzing the spectra of the light that a star emits 2 What color are the warmest stars? A yellow B blue C white D red 30.1 Characteristics of Stars Stellar Motion · apparent motion visible to the unaided eye caused by Earth's rotation appear to move counter-clockwise around Polaris (the North Star) different stars appear in different seasons circumpolar stars - always visible in the night sky Red Shift = star moving away · actual rotate on an axis revolve around another star move away from or toward our solar system · Doppler effect shifting wavelengths of light emitted by a light source moving toward or away from an observer blue shift = moving toward Earth red shift = moving away from Earth Distances to Stars · light-year = distance light travels in one year 9.46 trillion km/year sun = 8 light minutes away Proxima Centauri = 4.2 light-years away Polaris = 700 light-years away · parallax = apparent shift in a star's position when viewed from different locations accurate up to 1000 light-years 3 Why do stars appear to move in the sky? Blue shift = star moving toward Stellar Brightness · visibility of a star depends on brightness (magnitude) and distance from Earth 1 = brightness stars 6 = faintest stars · apparent magnitude = brightness of a star from Earth · absolute magnitude = how bright a star would be if it were 32.6light-years from Earth aka true brightness compared against a standard 4 Scientists use parallax to determine A a star's distance A the sky is rotating B if the star is moving toward or away from Earth B the universe is expanding C the brightness of a star C Earth is moving D a star's actual motion D galaxies are forming