Outline

Measuring the Properties of Stars 177

6.1 Measuring a Star's Distance 178

Measuring Distance by Triangulation and Parallax 178

Measuring Distance by the Standard-Candles Method 180

Extending Our Reach: Measuring the Distance to Sirius 181

6.2 Measuring the Properties of Stars from Their Light 182

Temperature 182

Luminosity 183

The Inverse-Square Law and Measuring a Star's Luminosity 183

Radius 184

The Stefan-Boltzmann Law 185

Extending Our Reach: Measuring the Radius of the Star Sirius 187

The Magnitude System 187

6.3 Spectra of Stars 188

Measuring a Star's Composition 189

How Temperature Affects a Star's Spectrum 190

Classification of Stellar Spectra 190

Re-Modeling: New Spectrum Classes 192

Definition of the Spectral Classes 192

Measuring a Star's Motion 193

6.4 Binary Stars 195

Visual and Spectroscopic Binaries 196

Measuring Stellar Masses with Binary Stars 197

Eclipsing Binary Stars 198

6.5 Summary of Stellar Properties 199

6.6 The H-R Diagram 199

Constructing the H-R Diagram 200

Analyzing the H-R Diagram 201

Giants and Dwarfs 202

The Mass-Luminosity Relation 202

Luminosity Classes 203

Summary of the H-R Diagram 204

6.7 Variable Stars 204

6.8 Finding a Star's Distance by the Method of Standard Candles 206

Project 210