IUPUI AST 105 - Star (3 pages)

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from Feb. 3rd Stars

Lecture number:
Lecture Note
Indiana University - Purdue University Indianapolis
Ast 105 - Stars and Galaxies

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AST 105 1nd Edition Lecture 6 Outline of Last Lecture I Stefan Boltzmann Law II Planck s Law III Spectra IV Spectroscopy a Analysis of light V Modern Theory of Atom a Niels Bohr VI Bohr s Law VII Doppler Shif a Blue shif b Red Shif Outline of Current Lecture Topic Stars I Local Stars a Proxima Centauri b Parallax i How we know distance from stars ii Parallax formula c Temperatures of Stars a Surface temp of distant stars b Two methods to find i Photomomy ii Spectroscopy Classifying Stars II III Current Lecture Stars Our sun is one of 1022 stars in the visible universe In our galaxy milky way there are about 1011 stars Our sun is about 5 billion years into its 10 billion year life cycle where its converting hydrogen into helium These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute Many of the stars we observe out of the 1022 are at different points in their life cycle We call life cycles of stars stellar evolution During stellar evolution the size temp color and luminosity of a star can vary Local Stars Closest neighbor is Proxima Centauri About 4x1016 meters away Q How do we know this distance o A Parallax Parallax o As the earth orbits around the sun a nearby star shifs its location against the background of very distant stars Only works for nearby stars Employs geometry Parallax Formula o Tan opposite leg adjacent leg x If when is small tan So x over d x d AND OR d x over X distance from sun to earth 1 58x10 5 LY average distance Q How do we know surface temperatures of stars A analyze the light of the star 2 methods to do that photomemy and spectroscopy Temperatures find temp by analyzibg the light from the distant star 2 methods to do this photomemy spectroscopy o Photomemy Focuses on colors Intensity brightness of star light at 3 different wavelengths is compared to the black body intensity curves Then a best fit will give us the surface temperature o Spectroscopy

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