lec16 - Lecture 16 Properties of Stars Lecture 16 Purdue...

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Lecture 16 Properties of Stars Purdue University, Astronomy 364 1 Lecture 16
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Distance Ladder • Radar ranging: solar system • Parallax: up to 500 pc • “Standard candle”: 5-100 kpc with RR Lyrae variables, 1 kpc-30 Mpc with Cepheid variables, 1 to over 1000 Mpc with Type Ia supernovae • Spectroscopic Parallax: 40 pc-10 kpc • “Standard yardstick” 2 Purdue University, Astronomy 364 Lecture 16
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Luminosity Distance • For a standard candle of luminosity L , from the measured flux F from the source one defines the luminosity distance to it as • Luminosity distance is an observational concept. d L L 4 π F 1/2 3 Purdue University, Astronomy 364 Lecture 16
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Angular-Diameter Distance • For a standard yardstick of current proper length l , from the measured angular size  of the yardstick one defines the angular-diameter distance to it as • Like luminosity distance, angular-diameter distance is also an observational concept . d A l δθ 4 Purdue University, Astronomy 364 Lecture 16
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Intrinsic vs Apparent Brightness • Intrinsic brightness – Bolometric luminosity: overall radiative power
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This note was uploaded on 04/23/2011 for the course ASTR 364 taught by Professor Cui,weik. during the Spring '11 term at Purdue University-West Lafayette.

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lec16 - Lecture 16 Properties of Stars Lecture 16 Purdue...

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