Binary Stars
Double Stars/Binary Stars
Binary Star
Double StarEarth
Earth
Visual Binary Stars
Orbit of Star 1
Orbit of Star 2
Center of Mass
Sirius A & B
Orbit of 12 Persei(Barlow, Scarfe, and Fekel
Visual Binaries
Stars must be either close to us or far from each other.Long orbital periods indicate they are far from
each other. (years to decades)
About 10% of all stars are visual binariesPossible planet detection
Spectroscopic Binaries
Spectrum of Hydrogen in Lab
Spectrum a Star…..Day 1
What do these spectra tell us about the star?
Spectrum a Star…..Day 2
Spectrum a Star…..Day 3
Spectrum a Star…..Day 4
Spectroscopic Binary Stars
Radial Velocity Curve
HDE 226868
Spectroscopic Binaries
Orbital Periods are several daysStars are close together
Orbits inclined 90° to sky are discovered this way.
All of the extra-solar planets have been found in this way.
Eclipsing Binary Stars
Roche Lobes
Classifications
Detached65 RT And
Semi-detached203 U Cep
Over-Contact12 XY Leo
Star Light Pro
Eclipsing Binaries
Chances of finding an eclipsing binaryInclined 90° to skyStars close together
Same conditions as spectroscopic binaryMany are discovered in both ways
Eclipsing binaries also permit radius to be determined
Relative radius
Eclipse beginsseparation = sum of radii
Second contactseparation = difference in radii
Time difference between these events gives radii of stars
Mass-Luminosity Relationship
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