BINARY STAR SYSTEMS
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Two stars are in a binary star system. Star A is 5 solar masses.
Star B is 2 solar masses. They are separated by a distance of 200
AU.  The period of Star A around the center of mass is _____ the
period for Star B around the center of mass.
   a) larger than
   b) smaller than
  $c) the same as

Which of the following would be a correct statement for stars in
a representative sample of 100 star systems?
  $a) Stars in binary systems are more common than single stars.
   b) Half of the stars would be in resolved visual binaries.
   c) Half of the stars would be eclipsing binaries.
   d) Most would be single stars.

In general, the orbits of binary stars are
   a) circular
   b) of high eccentricity
  $c) oriented more or less randomly in space
   d) tilted perpendicular to the line of sight.

Astrophysical uses of binaries:
------------------------------

The most important feature of binary stars is that they enable us
to determine stellar
   a) temperatures
   b) pressures
   c) compositions
  $d) masses

An astrometric binary is known to have an unseen companion whose
mass is about equal to the Sun's. The companion is most likely a:
   a) black hole
   b) pulsar
   c) supergiant
  $d) white dwarf
                              
If we know the distance to an eclipsing binary system, we can
determine the following property of the stars:
   a) Temperature.
   b) Radius. 
   c) Mass.
   d) Luminosity.
  $e) All of the above. 

In a certain spectroscopic binary, one star's spectral lines vary
in wavelength twice as much as the other.  The star whose lines
move more is
  $a) half the mass of the other
   b) twice the mass of the other
   c) twice as far from Earth as the other
   d) twice as luminous as the other

Classification:
--------------

If we observe the orbit of a binary star system face-on, it is
most likely to be detected as a binary
   a) spectroscopically (periodic velocity variation)
  $b) visually (separation in the plane of the sky)
   c) astrometrically (cyclic motion in the plane of the sky)
   d) by eclipses (periodic photometric variability)

If we observe more distant binary star systems, how are we most
likely to discover their binarity?
  $a) spectroscopically (periodic velocity variation)
   b) visually (spatially resolved)
   c) astrometrically (cyclic motion in the plane of the sky)
   d) by eclipses (periodic photometric variability)

Compared to other types of binaries, a binary star system discovered
as a visual binary is likely to have relatively
   a) high orbital velocities
  $b) large separation, long period
   c) large separation, short period
   d) small separation, long period
   e) small separation, short period

For a long-period spatially resolved (visual) binary, the
observations that suggest it to be a binary system are the
   a) velocity curves of the components
   b) differing brightnesses (eclipses)
   c) Doppler velocities of the components
  $d) small separation and common proper motion

When compared to visual, spectroscopic, or eclipsing binaries,
optical doubles are not true binaries because
   a) they are only binaries in the optical
  $b) they are are not gravitationally bound
   c) their radial velocities do not vary
   d) they have no proper motions 

If we see the orbital plane of two tightly bound stars nearly
edge on, which way are we most likely to discover the binary
system?
  $a) spectroscopic and eclipsing
   b) spectroscopic and long-period
   c) visual and astrometric
   d) visual and eclipsing

Which of the following is most likely?
   a) A spectroscopic binary has a period of over a decade.
   b) A spectroscopic binary is also a visual binary.
   c) A system which produces a nova is also a visual binary.
  $d) An eclipsing binary is also a spectroscopic binary.
   e) An eclipsing binary is also a visual binary.
                                                              
Light curves:
------------

Flat-bottomed minima in the light curve of an eclipsing binary
imply
   a) a large temperature difference between the components
   b) eccentric orbits
   c) partial eclipses
   d) tidal distortion
  $e) total and annular eclipses

If a spectroscopic binary is also eclipsing, the maximum Doppler
shift in the spectral lines occurs
   a) each time an eclipse takes place.  
   b) every other time an eclipse takes place.  
  $c) halfway between eclipses.
   d) between eclipses, but the timing depends on inclination.

In an eclipsing binary, the deeper (less bright) eclipse occurs
when the ______ star is being eclipsed.
  $a) hotter
   b) larger
   c) more luminous
   d) more massive
   e) smaller

For an eclipsing binary, from just the light curve one can find
the
   a) masses of both stars.
   b) luminosities of both stars.
   c) relative masses and diameters of the stars.
   d) relative masses of the stars.
  $e) relative sizes of the stars.