Astronomy Chapter 17 Test Questions – Flashcards
Unlock all answers in this set
Unlock answersquestion
About how many stars can be seen from somewhere on Earth with the naked eye?
answer
6000
question
About how many stars has the Hipparcos mission given us accurate distance data on?
answer
a million
question
Procyon lies about 13 light years distant, thus its parallax is about:
answer
.25''
question
In order to turn a star's proper motion into its space velocity, we must also know:
answer
distance and radial velocity
question
If a star appears to move back and forth relative to other stars over a six-month period, this motion is due to the star's:
answer
parallax shift
question
If a star appears to move relative to other stars over a one-year period, this motion is due to the star's:
answer
true space motion
question
What is the absolute magnitude of our Sun?
answer
+4.8
question
The absolute magnitude of a star is its brightness as seen from a distance of:
answer
10 parsecs
question
In comparing first magnitude Deneb with second magnitude Polaris, we find that:
answer
Deneb appears 2.5 times brighter to us than does Polaris.
question
At the distance of Jupiter (6 times further away from the Sun than Earth) the amount of sunlight received per square centimeter different by what factor?
answer
36 times less
question
A nearby star has a parallax of 0.2 arc seconds. What is its distance?
answer
5 parsecs
question
Star A and star B both have an apparent magnitude of 4.0, but star A has an absolute magnitude of 1.0 and star B has an absolute magnitude of 7.0. Which statement below is correct?
answer
Star A and star B appear to have the same brightness, but actually star A is brighter than star B.
question
Star A and star B both have an apparent magnitude of 7.0, but star A is at a distance of 15 pc and star B is at a distance of 30 pc. Which statement below is correct?
answer
Star A and star B appear to have the same brightness, but actually star B is brighter than star A.
question
Star A and star B both have an absolute magnitude of 2.0, but star A is at a distance of 50 pc and star B is at a distance of 20 pc. Which statement below is correct?
answer
Star B appears brighter than star A, but actually star B and star A are the same brightness.
question
Star A and star B both have an absolute magnitude of 2.0, but star A has an apparent magnitude of 5.0 and star B has an apparent magnitude of 7.0. Which statement below is correct?
answer
Star A appears brighter than star B, but actually star B and star A are the same brightness.
question
Star A has an absolute magnitude of 2.5 and star B has an apparent magnitude of 2.5, but star A is a main sequence star and star B is a red giant. Which statement below is correct?
answer
It is impossible to determine how bright these stars are or appear to be relative to one another, given the information above.
question
What are the two most important intrinsic properties used to classify stars?
answer
luminosity and surface temperature
question
What physical property of a star does the spectral type measure?
answer
temperature
question
The star's color index is a quick way of determining its:
answer
temperature
question
The most famous G type star is:
answer
the sun
question
Two red stars have surface temperatures of 3000 K, but Star A's luminosity is about 5% of the Sun's and Star B's luminosity is about 32,000 times the luminosity of the Sun. How much bigger is star B than star A?
answer
Star B's radius is about 800 times larger than star A's radius.
question
What is proper motion?
answer
annual apparent motion of a star across the sky
question
Star A is a main sequence star of spectral type F2 and star B is a white dwarf of spectral type B4. Which statement below is correct?
answer
Star B is hotter than Star A
question
Star A is a main sequence star of spectral type G5 and star B is a red giant of spectral type K2. Which statement below is correct?
answer
Star A is hotter than Star B
question
Stars that have masses similar to the Sun's, and sizes similar to the Earth are:
answer
white dwarfs
question
Compared to the size of the Sun, in what range of sizes are nearly all stars found?
answer
.01 to 100 solar radii
question
On the H-R diagram, the Sun lies:
answer
about the middle of the main sequence.
question
Which of the following is the most common type of star?
answer
low mass main sequence
question
The Hertzsprung-Russell Diagram plots ________ against the spectral type or temperature.
answer
luminosity or absolute magnitude
question
How might the most common occurring stars be described, based on our stellar neighborhood?
answer
M main sequence
question
On the H-R diagram, red supergiants like Betelguese lie:
answer
at the top right
question
On the H-R diagram, white dwarfs lie Sirius B and Procyon B lie:
answer
at the lower left
question
Which statement about stellar motion is incorrect?
answer
Like parallax, proper motion is measured over intervals of exactly six months.
question
In the H-R diagram, the bright blue-white stars that dominate the naked eye sky lie to the:
answer
top left
question
Having nothing to do with trigonometry, ________ parallaxes use the width of absorption lines to estimate the star's luminosity and size and distance.
answer
specteroscopic
question
In general, the narrower the spectral line of a star:
answer
the bigger the star is
question
Upon what data do measurements of sizes of eclipsing binaries depend?
answer
their doppler shifts and durations of stages during their eclipses
question
Which type of Binary can have their sizes measured by photometry?
answer
eclipsing
question
In what range of masses are most stars found?
answer
.1 to 100 solar masses
question
In a visual binary system with circular orbits, if in 20 years the two stars' position angles have shifted by 30 degrees, the pair's period must be:
answer
240 years
question
In a spectroscopic binary system, the star showing the larger blue shift is:
answer
less massive of the pair and receding slower
question
In a spectroscopic binary, if a pair shows a combined set of lines tonight, but a maximum split two nights later, its orbital period must be:
answer
eight days
question
What is the single most important characteristic in determining the course of a star's evolution?
answer
mass
question
Which of the following best describes the size and distance relationship of our Sun and the nearest star?
answer
2 marbles separated by 300 km
question
What is the typical main sequence lifetime of an M-type star?
answer
a trillion years
question
What is the typical main sequence lifetime of a G-type star?
answer
10 billion years
question
What is the typical main sequence lifetime of a B-type star?
answer
20 million years
question
For a star of 10 solar masses, its main sequence life span will be:
answer
only 1/1000th of the sun
question
If a star has a parallax of 0.05", then its distance in light years is about:
answer
65 light years
question
If a star is found by spectroscopic observations to be about 500 parsecs distant, its parallax is:
answer
.002''
question
The ESA's GAIA project will be able to measure parallax and stellar properties of about how many stars?
answer
1 billion
