2 Stellar Masses

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2 - Stellar Masses Radii
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Stellar Radii
Lunar Occultations
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Michelson Interferometry
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Intensity (Hanbury Brown) Interferometry
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Speckle Interferometry
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Adaptive Optics Imaging
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High Resolution Imaging from Space
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Main Sequence
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Keck
CHARA
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Space Interferometry Mission (SIM)
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Terrestrial Planet Finder (TPF)
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• Optical Doubles 2 stars in the line of sight
  with no physical relationship.
• Visual Binaries Two physically related stars
  orbiting one another that can be resolved
  independently.
• Astrometric Binaries Physically the same as a
  visual binary, except that one member is too
  faint to be detected.
• Eclipsing Binaries here, the plane of the orbit
  is so close to the line of sight that the stars
  pass in front of one another as they orbit their
  mutual center of mass.
• Spectrum Binaries Unresolved binary where the
  spectra of both stars are visible, but no orbital
  motion is detected through the Doppler effect.
• Spectroscopic Binaries Here, the orbital
  velocity and orbital inclination provide a
  Doppler shift large enough to be detected.

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? Cyg Albireo
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For a pair of stars with masses m1 and m2,
located a1 and a2 from the center of mass
We dont measure as directly, but the angular
separation ? in arcsec
Keplers 3rd Law
in astronomers units
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Masses from Spectroscopic Binaries
We see only the radial component of the orbital
velocity
So we measure
Similarly,
But you need to know i pretty well
In many cases you see only the spectrum of star 1
and all you can find is the mass function
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L vs M for Main Sequence Stars
The Main Sequence is a sequence of masses