AST-L16-ch11__3

AST-L16-ch11__3 - AST 1002 Planets, Stars and Galaxies...

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1 Analyzing Starlight: finding the properties of stars (Astrometry) Measuring the Properties of Stars measuring stars’ Temperature AST 1002 Planets, Stars and Galaxies 1) measuring stars’ Composition measuring stars’ Distance measuring stars’ Luminosity measuring stars’ Size measuring stars’ Mass 2) Properties of Stars 3) H-R diagrams Today’s Lecture: purpose & goals Observing Stars We study stars by observing their light What can we learn about stars? Brightness/luminosity Distance from us Velocity (has fast/what direction) Mass Size Composition Ultimately, we would like to find common characteristics between stars and learn the how and why of them. Review – atoms & spectra (lecture2) Properties of waves wavelength, frequency, period, speed Light is an electromagnetic wave (different types of “light” correspond to different wavelengths ) Atoms/energy levels absorption and emission of photons Doppler effect Temperature and light all objects emit light (blackbody radiation) hotter = bluer & brighter E=h ν =hc / λ v r/ c = Δλ / λ ο
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2 Temperature and Light All Warm or Hot objects give off light Temperature is a measure of how fast the atoms/molecules are moving hot atoms move faster than cooler atoms faster movement means more collisions Collisions of atoms can convert internal energy to light This is what causes an incandescent light bulb to glow Temperature and Light All objects radiate light that is dependant on their temperature.
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This note was uploaded on 10/13/2011 for the course AST 1002 taught by Professor Gerstein during the Spring '08 term at FSU.

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AST-L16-ch11__3 - AST 1002 Planets, Stars and Galaxies...

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