# Ast 111 last test

 how we may find the distance to nearby stars with the method of Stellar Parallax The small annual shifts in star's apparent position caused by Earth's motion around the sun.Comparing observations of nearby star made 6 months apartIf we know the stars precise amount of shift distant stars have smaller Parallax angle What are parallax angles measured as? Arcseconds What is an arcsecond 1/60 of an arc minute1/3600 of 1 degree What is a parsec distance in parsec = 1/p P = parallax angle in seconds distance to an object with a parallax angle of 1 arcsecond; approximately equal to 3.26 light years Light year The distance light takes to travel in a year Stellar magnitude Measure the brightness of stars on a scale of stellar magnitudesAncient Greeks made sky maps #1=very bright, #6 faintest you can see my eye Today's Stellar Magnitudes 5 different magnitudesfactor in brightness of 100EX #1 is 100x brighter than #6 Apparent Magnitude How bright a star appears to be on the sky Absolute magnetude Measure the intrinsic brightness of the star At what distance would a star’s apparent magnitude equal its absolute magnitude? 10 parsecs away Apparent Magnitude of sun vs. Absolute magnitude Apparent = -26.7Absolute = +4.5 spectraltype Astronomers use the various absorption lines in the spectrum of a star to define Absorption spectra of starts original classification system based on strength of the hydrogen absorption lines early spectra types A very strong H absorption linesP very weak H absorption lines What do we know governs what spectra looks like more than anything else Temperature Who started the classification system today? Annie J. Cannon Spectra types today OBAFGKMhottest - cool starso0-o9 b0-b9The sun is a G2A type stars have the strongest H absorption lines Authorsummer.sproull ID212151 Card SetAst 111 last test Descriptionlast test Updated2013-04-08T15:55:53Z Show Answers