1.

Stellar parallax is the A. elliptical motion of a star in a binary system, as the two stars orbit around each other. B. difference between the apparent magnitude and the absolute magnitude of a star. C. assumed change in the distance to a star when it dims, as it passes through an interstellar cloud. D. apparent shift in the position of a nearby star because of the Earth's motion.

2.	Stellar parallax is used to determine which of the following properties of a nearby star? A. its spectral type and surface temperature B. its rotation period C. its apparent magnitude D. its distance from the Sun

3.	Light, leaving a point source, spreads out so that the apparent brightness, I , of light per unit area varies with distance d according to which law (µ means "proportional to")? A. I µ 1/d2. B. I = constant. C. I µ 1/d. D. I µ d2.

4.	Suppose that two identical stars (having the same total light output or luminosity) are located such that star A is at a distance of 5 pc and star B is at a distance of 25 pc. How will star B appear, compared to star A? A. 1/2.2 as bright B. 1/25 as bright C. 1/20 as bright D. 1/5 as bright

5.

Which of the following statements is true of the population of stars in our neighborhood? A. There are many more bright than faint stars. B. There are about equal numbers of stars of various brightness. C. There are more stars of intermediate brightness and less fainter or brighter stars. D. There are many more faint than bright stars.

6.	The luminosity of a star is A. another name for its color or surface temperature. B. its brightness as seen by people on Earth. C. its total energy output into all space over all wavelengths. D. its brightness at a hypothetical distance of 10 parsecs (32.6 light-years) from Earth.

7.	Apparent magnitude is a measure of the A. intrinsic brightness (actual light output) of a star. B. brightness of a star, as seen from the Earth. C. size (diameter) of a star. D. temperature of a star.

8.	The ratio of the brightness of a star at two different colors, blue and visual—bV/bB—is a direct measure of what property of the star? A. distance from Earth B. surface temperature C. luminosity D. radius

9.

The star Rigel, in the constellation Orion, appears brighter through a blue filter than it does through a yellow filter. Suppose a second star is found that has the same brightness as Rigel through the yellow filter but is brighter than Rigel through the blue filter. From this information, we can say conclusively that the second star has A. a higher temperature. B. the same temperature but a higher luminosity. C. a lower temperature. D. the same temperature but a lower luminosity.

10.

What effect does interstellar dust have on the apparent color of a star seen through the dust? A. The dust makes the star look brighter than it really is, but leaves the color of the star unchanged. B. The dust makes the star look bluer than it really is. C. The dust makes the star look fainter than it really is, but leaves the color of the star unchanged. D. The dust makes the star look redder than it really is.

11.

The spectrum of an ordinary main sequence star is a A. continuum of colors crossed by dark absorption lines, caused by absorption of cooler atoms and molecules at the surface. B. smooth continuum of color, peaking at a specific wavelength whose position is dependent on the surface temperature. C. series of emission lines, mostly from hydrogen, the major constituent of stellar surfaces, that occasionally overlap to produce sections of continuous color. D. continuum of colors crossed by brighter lines caused by emission of hot atoms and molecules on the surface.

12.	What is "metal" to an astronomer? A. any element heavier than hydrogen B. any element heavier than hydrogen or helium C. any element in solid or liquid form that can conduct electricity easily D. any element

13.	Which two vital parameters are used to describe the systematics of a group of stars (e.g., cluster) in the Hertzsprung-Russell diagram? A. luminosity and radius B. surface temperature and mass C. luminosity and surface temperature D. mass and apparent magnitude

14.

Where on the Hertzsprung-Russell diagram do most local stars in our universe congregate? A. in the supergiant area, where the most massive stars spend a significant time B. in the giants area, where most stars spend the longest time of their lives C. in the white dwarf area, the "graveyard" of stars D. on the main sequence where stars are generating energy by fusion reactions

15.	What fraction of the stars in the night sky are main-sequence stars? A. almost none of them, less than 1% B. relatively few of them, about 20% C. almost all of them, about 90% D. roughly half of them, about 55%

16.	What is the size of a star in the upper right part of the Hertzsprung-Russell diagram compared to one in the middle of the diagram? A. It is fainter. B. It is hotter. C. There are no stars in the upper right part of the diagram. D. It is larger.

17.

Measurements indicate that a certain star has a very high intrinsic brightness (100,000 times as bright as our Sun) and yet is relatively cool (3500 K). How can this be? A. There must be an error in observation, since no star can have this form. B. The star must be quite small. C. The star must belong to the main sequence. D. The star must be very large.

18.	What proportion of visible stars in the night sky are multiple-star systems? A. about 25%, or 1/4 B. less than 1% C. nearly 100% D. about 50%, or 1/2

19.

In a particular binary star system, only one star is visible because the other star is too faint to see at that distance. An astronomer measures the size (semimajor axis) and period of the orbit of the visible star. From this information the astronomer can calculate A. nothing about the mass—both stars have to be visible to do so. B. the mass of each star. C. the sum of the masses of the two stars but not the mass of each star separately. D. the mass of the visible star but not that of the unseen star.

20.

How do two unequal mass stars move around each other in a binary system? A. in a common elliptical orbit, always remaining diametrically opposite to each other through one of the foci of the ellipse B. in straight lines, back and forth past each other C. in elliptical orbits, about a common "center of mass" D. The low-mass star moves in a circular orbit around the stationary high-mass star.

21.

The relationship between mass and luminosity of stars on the main sequence is that A. the luminosity of stars rises to a peak at around a mass of 1 solar mass and decreases as mass increases beyond this limit. B. the greater the stellar mass, the larger the luminosity. C. luminosity is independent of the stellar mass. D. the greater the stellar mass, the less the luminosity.

22.

The radial-velocity curve of a star in a binary star system is a plot against time of the A. speed of the star in a direction perpendicular to the line of sight to the star. B. temperature of the star as determined from the movement of the peak wavelength of its spectrum. C. position of the star in celestial coordinates. D. variation of Doppler shift of its spectral lines and hence of its speed toward or away from us.

23.

An eclipsing binary system is A. two stars whose spectral lines move back and forth, indicating relative motion. B. a star that is periodically eclipsed by the Moon. C. two stars whose combined light output when measured from Earth appears to vary periodically as the two stars move in front of one another. D. two stars that are clearly seen as separate but associated in the sky.

24.

The components of a binary star, particularly if they are close, can influence each other in various ways. Which of the following is NOT likely to be an effect of one star on its companion? A. The gravitational force of one star will make its companion move in an orbit rather than remaining stationary. B. A very hot star can heat part of its cooler companion to produce a hotspot. C. Intense radiation from a hot star can produce nuclear reactions on the surface of a cooler companion and initiate a nova explosion. D. Mass can be transferred from one star to its companion.

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