an inference from the mass-luminosity relation is that
A all stars have equal lifetimes.
B all stars have the same age.
C more massive stars live longer lives.
D more massive stars live shorter lives.
an eclipsing binary with total eclipses allows you to calculate the ratio of the _____ of the stars.
A masses
B sizes
C distances
D no choice
double stars are important in astronomy because
A all stars are double
B they are very beautiful
C they evolve quickly enough for us to see the changes
D study of their orbits allows us to determine their physical properties
observations of binary stars have helped astronomers to determine which important stellar parameter for these stars?
A stellar mass
B pulsation period
C surface temperature
D distance from Earth
strong support for the theory of planet formation discussed in class is the existence of
A galaxies
B black holes
C binary star systems
D many stars similar to the sun
a double line spectroscopic binary has two stars of
A nearly equal brightness
B low actual brightness
C high actual brightness
D no choice
the study of binary stars is important because
A they are completely different from single stars
B we can measure their age
C their distance is known
D we can use the laws of orbits to determine their mass and size
in what way will two stars in a binary system orbit each other, in general
A the larger mass star orbits around the center of the smaller mass star
B they both follow elliptical orbits around a common point between the stars
C they both move in elliptical orbits around a point on the line joining the two star centers, closest to the less massive star
D the lower mass star orbits in an ellipse around the center of the larger m star
in order to determine the size of a star in a binary system, one must have
A an eclipsing system whose distance is known
B a double-line spectroscopic system
C an eclipsing system which is also a spectroscopic binary
D a visual binary whose distance is known
why are eclipsing binary systems important?
A eclipses give information on the stars' atmospheres.
B they yield data on stellar masses.
C evolution proceeded differently in such systems.
D they are very young stars.
E none of the above.
a system which is both a double line spectroscopic and an eclipsing binary allows you to calculate
A the masses of the stars
B the sizes of the stars
C all of the orbit parameters
D all of the above
in binary stars, the two stars move in which way with respect to each other
A the low-mass star moves in a circular orbit around the stationary high-mass star
B in straight lines, back and forth past each other
C in circular orbits around the center of the galaxy
D in elliptical orbits, about a common "center of mass"
a double-line spectroscopic binary consists of two stars which are
A nearly equal in size
B also a visual binary system
C nearly equal in brightness
D nearly equal in temperature
binary star systems are especially important to us because they allow us to calculate the _______ of stars.
A compositions
B proper motions
C radial velocities
D temperatures
E masses
the unknown orbit parameter of a spectroscopic binary is
A the eccentricity
B the angle of inclination
C all parameters are known
D no choice
the existence of planetary systems around other stars has been shown
A by detecting a wobble in the motion of nearby stars against the distant background stars
B by direct observation of other planets
C to be highly unlikely, if not impossible
D to be an unanswerable question.
which of the following is not needed in order to determine the individual masses of stars in a binary system?
A orbital period.
B location of the center of mass.
C Kepler's third law.
D distance to the binary system.
E colors of each of the stars.
the method of dynamical parallaxes can be used for which type of binary star system?
A spectroscopic
B eclipsing
C visual
D none of the above
binary stars are important in astronomy because
A they are so rare
B they are beautiful when observed in telescopes
C astronomers can determine their fundamental properties
D they usually lead to violent explosions
imagine that you observed a binary star system face on, so that you are looking directly down on the orbital plane. what do you expect of the Doppler shift from this system?
A always show red shifts.
B always show blue shifts.
C alternate between red and blue shifts.
D show no Doppler shift at all.
binary stars are important because
A they are very rare
B they are beautiful
C study of their orbits allows us to find their mass
D their motion is determined by their age
what is the most important reason for observing binary stars?
A to measure stellar masses.
B to measure stellar radii.
C to discover planets.
D to detect black holes.
the primary minimum of an eclipsing binary occurs when the ____ star is eclipsed
A hot
B bright
C cool
D no choice
the formation of binary stars is thought to be a process analogous to
A the formation of a galaxy
B the formation of spiral arms in a galaxy
C the formation of a planetary system
D the formation of a cluster of galaxies
the only way which we have discussed to determine the size of a star is by analyzing
A a visual binary
B a spectroscopic binary
C an eclipsing binary
D a cepheid variable
the method of dynamical parallaxes is used to calculate the _____ of visual binary stars
A relative sizes
B distances
C masses
D no choice
which types of binary stars provide information on masses and radii of the individual stars.
A eclipsing binaries.
B spectroscopic binaries.
C visual binaries.
D contact binaries.
the mass-luminosity relation tells you that
A more massive stars are bigger.
B more massive stars are more luminous.
C the less massive stars are more luminous.
D the less massive stars are bigger.
a double line spectroscopic binary allows you to calculate the ratio of the _______ of the stars
A masses
B sizes
C orbits
D no choice
what proportion of visible stars in the nighttime sky are multiple-star systems, such as double stars?
A less than 1%
B about
C about 1/4
D nearly 100%
if one is to measure a star's mass, it must
A not exhibit any parallax motion
B be more massive than five solar masses
C have a known chemical composition
D have a companion star
if two stars in a binary system pass alternately in front of each other as seen from Earth, we have a _____ binary
A spectrum
B eclipsing
C optical
D spectroscopic
a visual binary star is
A one whose brightness drops periodically as one of its members passes in fr of the other
B one whose members can be seen as separate stars through a telescope
C one which looks like a single star but whose spectrum can only be explained as being produced by more than one star
D a star whose proper motion reveals that it has planet-sized companions
the orbit of an eclipsing binary is always seen
A from the top
B edge on
C at no particular orientation
D no choice
stellar diameters may be determined from studies of
A visual binary stars
B astrometric binary stars
C spectroscopic binary stars
D eclipsing binary stars
eclipsing binaries are identified by
A changing brightness
B changes in the intensity of some of the spectral lines
C changes in the position of the spectral lines
D changes in the position of the stars
a star's mass may be most precisely measured if
A its motion around the galaxy's core can be observed for several full orbit
B its luminosity is known precisely
C it is a member of a binary star system
D it has planets
spectroscopic binaries are identified by
A changing brightness
B changes in the intensity of some of the spectral lines
C changes in the position of the spectral lines
D changes in the position of the stars
binary stars allow us to derive which important stellar parameter
A surface temperature
B stellar mass
C the Einstein gravitational red shift
D distance from Earth
an eclipsing binary star is
A one whose brightness drops periodically as one of its members passes in front of the other
B one whose members can be seen as separate stars through a telescope
C one which looks like a single star but whose spectrum can only be explained as produced by more than one star
D a star whose motion reveals that it has planet-sized companions
the size of a star may be determined by analyzing
A an eclipsing binary
B a spectroscopic binary
C a visual binary
D a cepheid variable
if the spectrum of a star shows changing Doppler shifts over time then it is probably a(n)
A variable star
B eclipsing binary star
C spectroscopic binary star
D visual binary star
binary stars are particularly important for determining stellar
A temperature
B luminosity
C distance
D mass
visual binaries are
A any two stars orbiting about each other
B an orbiting pair of stars each of which is detectable with a telescope
C chance apparent coincidence of stars in the sky
D stars with observed planetary systems
an eclipsing binary system is
A two stars which periodically pass in front of each other
B two stars, detected as such by movement of lines in their spectra by Doppler shift
C a star which is periodically eclipsed by the moon
D two stars clearly separated, when viewed from Earth
a star that is determined to be a binary because of its velocity changes is called:
A an astrometric binary.
B an eclipsing binary.
C a visual binary.
D a spectroscopic binary.
the mass-luminosity relation for main-sequence stars tells you that
A the more massive stars are bigger.
B the more massive stars are brighter.
C the less massive stars are brighter.
D the less massive stars are smaller.
why are binary stars so important to astronomers?
A because we can determine the center of their masses.
B because they are so rare they tell us something new about the universe.
C because it is only from binary stars that we can determine stellar masses.
D because they give us an opportunity to use Kepler's laws of orbits
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