# Astronomy Chapter 17 Test Questions

Flashcard maker : Robert May
About how many stars can be seen from somewhere on Earth with the naked eye?
6000
About how many stars has the Hipparcos mission given us accurate distance data on?
a million
Procyon lies about 13 light years distant, thus its parallax is about:
.25”
In order to turn a star’s proper motion into its space velocity, we must also know:
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:
parallax shift
If a star appears to move relative to other stars over a one-year period, this motion is due to the star’s:
true space motion
What is the absolute magnitude of our Sun?
+4.8
The absolute magnitude of a star is its brightness as seen from a distance of:
10 parsecs
In comparing first magnitude Deneb with second magnitude Polaris, we find that:
Deneb appears 2.5 times brighter to us than does Polaris.
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?
36 times less
A nearby star has a parallax of 0.2 arc seconds. What is its distance?
5 parsecs
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?
Star A and star B appear to have the same brightness, but actually star A is brighter than star B.
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?
Star A and star B appear to have the same brightness, but actually star B is brighter than star A.
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?
Star B appears brighter than star A, but actually star B and star A are the same brightness.
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?
Star A appears brighter than star B, but actually star B and star A are the same brightness.
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?
It is impossible to determine how bright these stars are or appear to be relative to one another, given the information above.
What are the two most important intrinsic properties used to classify stars?
luminosity and surface temperature
What physical property of a star does the spectral type measure?
temperature
The star’s color index is a quick way of determining its:
temperature
The most famous G type star is:
the sun
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?
What is proper motion?
annual apparent motion of a star across the sky
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?
Star B is hotter than Star A
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?
Star A is hotter than Star B
Stars that have masses similar to the Sun’s, and sizes similar to the Earth are:
white dwarfs
Compared to the size of the Sun, in what range of sizes are nearly all stars found?
On the H-R diagram, the Sun lies:
about the middle of the main sequence.
Which of the following is the most common type of star?
low mass main sequence
The Hertzsprung-Russell Diagram plots ________ against the spectral type or temperature.
luminosity or absolute magnitude
How might the most common occurring stars be described, based on our stellar neighborhood?
M main sequence
On the H-R diagram, red supergiants like Betelguese lie:
at the top right
On the H-R diagram, white dwarfs lie Sirius B and Procyon B lie:
at the lower left
Which statement about stellar motion is incorrect?
Like parallax, proper motion is measured over intervals of exactly six months.
In the H-R diagram, the bright blue-white stars that dominate the naked eye sky lie to the:
top left
Having nothing to do with trigonometry, ________ parallaxes use the width of absorption lines to estimate the star’s luminosity and size and distance.
specteroscopic
In general, the narrower the spectral line of a star:
the bigger the star is
Upon what data do measurements of sizes of eclipsing binaries depend?
their doppler shifts and durations of stages during their eclipses
Which type of Binary can have their sizes measured by photometry?
eclipsing
In what range of masses are most stars found?
.1 to 100 solar masses
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:
240 years
In a spectroscopic binary system, the star showing the larger blue shift is:
less massive of the pair and receding slower
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:
eight days
What is the single most important characteristic in determining the course of a star’s evolution?
mass
Which of the following best describes the size and distance relationship of our Sun and the nearest star?
2 marbles separated by 300 km
What is the typical main sequence lifetime of an M-type star?
a trillion years
What is the typical main sequence lifetime of a G-type star?
10 billion years
What is the typical main sequence lifetime of a B-type star?
20 million years
For a star of 10 solar masses, its main sequence life span will be:
only 1/1000th of the sun
If a star has a parallax of 0.05″, then its distance in light years is about:
65 light years
If a star is found by spectroscopic observations to be about 500 parsecs distant, its parallax is:
.002”
The ESA’s GAIA project will be able to measure parallax and stellar properties of about how many stars?
1 billion