ASTRONOMY EXAM 3 QUESTIONS AND
ANSWERS 100% CORRECT!!
, Most of the really bright stars in our sky are NOT among the stars that are very close to
us. Why then do they look so bright to us? - ANSWER these stars are intrinsically so
luminous, that they can easily be seen even across great distances
The most common kinds of stars in the Galaxy have - ANSWER low luminosity
compared to the Sun
Two stars that are physically associated (move together through space) are called -
ANSWER binary stars
Which of the following statements about spectroscopic binary stars is FALSE? -
ANSWER an analysis of the ways the lines in the spectrum change allows us to
calculate the star's distance directly
Which law do astronomers use to determine the masses of the stars in a spectroscopic
binary system? - ANSWER Kepler's Third Law
Which of the following has the smallest mass? - ANSWER a planet
Why can astronomers not measure the diameters of stars directly? - ANSWER stars are
so far away, we cannot resolve (distinguish) their diameters
For what type of star can astronomers measure the diameter with relative ease? -
ANSWER eclipsing binary stars
In an H-R diagram, where can you see the spectral type of a star (whether it is an O
type star or a G type star, for example)? - ANSWER along the bottom (the horizontal
axis)
Ninety percent of all stars (if plotted on an H-R diagram) would fall into a region
astronomers call - ANSWER the main sequence
Measurements show a certain star has a very high luminosity (100,000 x the Sun's)
while its temperature is quite cool (3500°K). How can this be? - ANSWER it must be
quite large in size
Imagine that powerful telescopes in the future give us a truly representative sampling of
all the stars in the Sun's cosmic neighborhood. Where on the H-R diagram would most
of the stars in our immediate vicinity lie? - ANSWER in the lower right, among the least
luminous main sequence stars
ANSWERS 100% CORRECT!!
, Most of the really bright stars in our sky are NOT among the stars that are very close to
us. Why then do they look so bright to us? - ANSWER these stars are intrinsically so
luminous, that they can easily be seen even across great distances
The most common kinds of stars in the Galaxy have - ANSWER low luminosity
compared to the Sun
Two stars that are physically associated (move together through space) are called -
ANSWER binary stars
Which of the following statements about spectroscopic binary stars is FALSE? -
ANSWER an analysis of the ways the lines in the spectrum change allows us to
calculate the star's distance directly
Which law do astronomers use to determine the masses of the stars in a spectroscopic
binary system? - ANSWER Kepler's Third Law
Which of the following has the smallest mass? - ANSWER a planet
Why can astronomers not measure the diameters of stars directly? - ANSWER stars are
so far away, we cannot resolve (distinguish) their diameters
For what type of star can astronomers measure the diameter with relative ease? -
ANSWER eclipsing binary stars
In an H-R diagram, where can you see the spectral type of a star (whether it is an O
type star or a G type star, for example)? - ANSWER along the bottom (the horizontal
axis)
Ninety percent of all stars (if plotted on an H-R diagram) would fall into a region
astronomers call - ANSWER the main sequence
Measurements show a certain star has a very high luminosity (100,000 x the Sun's)
while its temperature is quite cool (3500°K). How can this be? - ANSWER it must be
quite large in size
Imagine that powerful telescopes in the future give us a truly representative sampling of
all the stars in the Sun's cosmic neighborhood. Where on the H-R diagram would most
of the stars in our immediate vicinity lie? - ANSWER in the lower right, among the least
luminous main sequence stars
