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Chapter 29 Notes. Stars. The Sun: Solar Atmosphere. Photoshere : visible surface, 5800 K Chromosphere : 30,000 K Corona: 1 to 2 million K, solar wind extends from the corona. Solar Interior. Core: nuclear fusion Radiative zone: energy moves outward from the core
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Chapter 29 Notes Stars
The Sun: Solar Atmosphere • Photoshere: visible surface, 5800 K • Chromosphere: 30,000 K • Corona: 1 to 2 million K, solar wind extends from the corona
Solar Interior • Core: nuclear fusion • Radiative zone: energy moves outward from the core • Convective zone: currents carry energy to the surface
Solar Activity • Sunspots—11 year cycle • Solar wind • Prominences
Solar Energy • Nuclear fusion takes place in the core of the sun • Hydrogen nuclei fuse together to form helium • Energy is released • E=mc2 (E = Energy, m = mass, c = speed of light) • When hydrogen is gone, stars will form carbon, oxygen, neon, silicon, and iron—in that order
Electromagnetic Spectrum • Dark bands in the visible spectrum are caused by different chemical elements • 70% hydrogen 28% helium
Measuring Stars • Parallax is used to find the distance to stars • Constellations: Groups of stars in the same part of the sky • Clusters: groups of stars bound together by gravity • Binaries: two stars that orbit a common center of mass
Doppler Shift • Movement of a star affects the frequency of the light waves • Stars moving toward us are blueshifted, stars moving away are redshifted
Star Properties • Magnitude • Apparent magnitude: how bright the star appears from Earth • Absolute magnitude: how bright a star would look if it were 10 parsecs away • Luminosity: energy output per second • Composition of stars: ~73% hydrogen, ~25% helium, ~2% all other elements
Temperature • Temperature determines spectral class and color • Blue stars are hotter, red stars are cooler • Oh, be a fine girl, kiss me.
Star Life Cycle • Stars spend most of their “life” in the Main Sequence and so most stars are located in the Main Sequence section of the H-R diagram • Small mass stars burn fuel slowly and have a long life span • Large mass stars burn their fuel very quickly and are much brighter than small mass stars
Star “Life-Cycle” • Mass determines the future of a star