AST 1002 CORRECT FINALS ANSWERS AND
QUESTIONS SET A+
✔✔You observe a star cluster with a main-sequence turn-off point at spectral type G2
(the same spectral type as the Sun). What is the age of this star cluster? - ✔✔10 billion
years.
✔✔The most distant stars we can measure stellar parallax for are approximately -
✔✔100 parsecs away.
✔✔What are the standard units for apparent brightness? - ✔✔Watts per square meter
✔✔Which of the following statements about apparent and absolute magnitudes is true?
- ✔✔The absolute magnitude of a star is another measure of its luminosity.
The magnitude system that we use now is based on a system used by the ancient
Greeks over 2,000 years ago that classified stars by how bright they appeared.
A star with an apparent magnitude of 1 appears brighter than a star with an apparent
magnitude of 2.
A star's absolute magnitude is the apparent magnitude it would have if it were at a
distance of 10 parsecs from Earth.
✔✔Which of the following best describes the axes of a Hertzsprung-Russell (H-R)
diagram? - ✔✔surface temperature on the horizontal axis and luminosity on the vertical
axis
✔✔A star of spectral type G lives approximately how long on the main sequence? -
✔✔10 billion years
✔✔Which of the following correctly states the relationship between the apparent
brightness, luminosity, and distance of a star? - ✔✔apparent brightness =
(luminosity/4Ï€ x (distance) to power of ((2)).
, ✔✔Which of the following comparisons between low-mass stars and high-mass stars is
true? - ✔✔Low-mass stars are cooler and less luminous than high-mass stars.
✔✔What are the standard units for luminosity? - ✔✔Watts
✔✔You measure the parallax angle for a star to be 0.5 arcseconds. The distance to this
star is - ✔✔2 parsecs. Distance = 1/Parallax angle
✔✔Which of the following luminosity classes refers to stars on the main sequence? -
✔✔V
✔✔On a Hertzsprung-Russell diagram, where would you find white dwarfs? - ✔✔lower
left
✔✔Which of the following stellar properties has the greatest range in values? -
✔✔luminosity
✔✔You see two main-sequence stars with the same spectral type. Star 1 is dimmer in
apparent brightness than Star 2 by a factor of 100. What can you conclude, assuming
there is no absorption of either star's light by interstellar gas or dust? - ✔✔Star 1 is 10
times more distant than Star 2.
✔✔On a Hertzsprung-Russell diagram, where would you find red giant stars? -
✔✔upper right
✔✔Which of the following terms is given to a pair of stars that appear to change position
in the sky, indicating that they are orbiting one another? - ✔✔visual binary
✔✔Which of the following statements about globular clusters is true? - ✔✔Most stars in
the cluster are yellow or reddish in color.
✔✔The spectral sequence, in order of decreasing temperature, is - ✔✔OBAFGKM.
✔✔Which of the following is the most numerous type of main-sequence star? - ✔✔an M
star
✔✔What happens to the core of a star after it ejects a planetary nebula? - ✔✔It
becomes a white dwarf.
✔✔What percentage of a star's total lifetime is spent on the main sequence? - ✔✔90%
✔✔Suppose the star Betelgeuse (the upper left shoulder of Orion) were to become a
supernova tomorrow (as seen here on Earth). What would it look like to the naked eye?
QUESTIONS SET A+
✔✔You observe a star cluster with a main-sequence turn-off point at spectral type G2
(the same spectral type as the Sun). What is the age of this star cluster? - ✔✔10 billion
years.
✔✔The most distant stars we can measure stellar parallax for are approximately -
✔✔100 parsecs away.
✔✔What are the standard units for apparent brightness? - ✔✔Watts per square meter
✔✔Which of the following statements about apparent and absolute magnitudes is true?
- ✔✔The absolute magnitude of a star is another measure of its luminosity.
The magnitude system that we use now is based on a system used by the ancient
Greeks over 2,000 years ago that classified stars by how bright they appeared.
A star with an apparent magnitude of 1 appears brighter than a star with an apparent
magnitude of 2.
A star's absolute magnitude is the apparent magnitude it would have if it were at a
distance of 10 parsecs from Earth.
✔✔Which of the following best describes the axes of a Hertzsprung-Russell (H-R)
diagram? - ✔✔surface temperature on the horizontal axis and luminosity on the vertical
axis
✔✔A star of spectral type G lives approximately how long on the main sequence? -
✔✔10 billion years
✔✔Which of the following correctly states the relationship between the apparent
brightness, luminosity, and distance of a star? - ✔✔apparent brightness =
(luminosity/4Ï€ x (distance) to power of ((2)).
, ✔✔Which of the following comparisons between low-mass stars and high-mass stars is
true? - ✔✔Low-mass stars are cooler and less luminous than high-mass stars.
✔✔What are the standard units for luminosity? - ✔✔Watts
✔✔You measure the parallax angle for a star to be 0.5 arcseconds. The distance to this
star is - ✔✔2 parsecs. Distance = 1/Parallax angle
✔✔Which of the following luminosity classes refers to stars on the main sequence? -
✔✔V
✔✔On a Hertzsprung-Russell diagram, where would you find white dwarfs? - ✔✔lower
left
✔✔Which of the following stellar properties has the greatest range in values? -
✔✔luminosity
✔✔You see two main-sequence stars with the same spectral type. Star 1 is dimmer in
apparent brightness than Star 2 by a factor of 100. What can you conclude, assuming
there is no absorption of either star's light by interstellar gas or dust? - ✔✔Star 1 is 10
times more distant than Star 2.
✔✔On a Hertzsprung-Russell diagram, where would you find red giant stars? -
✔✔upper right
✔✔Which of the following terms is given to a pair of stars that appear to change position
in the sky, indicating that they are orbiting one another? - ✔✔visual binary
✔✔Which of the following statements about globular clusters is true? - ✔✔Most stars in
the cluster are yellow or reddish in color.
✔✔The spectral sequence, in order of decreasing temperature, is - ✔✔OBAFGKM.
✔✔Which of the following is the most numerous type of main-sequence star? - ✔✔an M
star
✔✔What happens to the core of a star after it ejects a planetary nebula? - ✔✔It
becomes a white dwarf.
✔✔What percentage of a star's total lifetime is spent on the main sequence? - ✔✔90%
✔✔Suppose the star Betelgeuse (the upper left shoulder of Orion) were to become a
supernova tomorrow (as seen here on Earth). What would it look like to the naked eye?
