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=mc 2 (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.

Spectral Types of Stars

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