Exam 17: The Nature of the Stars

A particular star has 12 times the radius of the Sun and only 60% of the Sun's surface temperature. What is the star's luminosity in solar units ( $L_{\odot}$ )? (See Box 17-4.)

How much smaller (in radius) than the Sun is a white dwarf star whose temperature is the same as that of the Sun? (See Figure 17-15b.(in the text))

The star Procyon has a parallax of 0.287 arcsec and a proper motion of 1.25 arcsec per year. What is the tangential velocity of Procyon?

The total apparent motion against the background sky as a result of Earth's motion halfway around its orbit of a star whose distance from the Sun is 40 pc is:

The star β Arietis has an apparent magnitude of +2.7 and a distance of 52 ly. What is its absolute magnitude, M?

How do two stars in a binary system orbit each other? (See Figure 17-21.(in the text))

An eclipsing binary system is:

The apparent angular movement of a nearby star against the background stars as a consequence of its motion in space is known as:

Two stars that differ from each other by five magnitudes have a ratio of brightness of:

Using the Hertzsprung-Russell diagram in Figure 17-15a and the mass-luminosity relationship for main-sequence stars shown in Figure 17-22, which of the following is the correct sequence of stars in increasing order of mass?

The star Hadar has a spectral classification of B1 III. This tells us that Hadar is a:

Why is it that stars with low surface temperature, much cooler than 10,000 K, show very weak or no hydrogen Balmer lines in absorption?

Using Figure 17-15, determine which of the following is the correct sequence of stars in order of increasing size or stellar radius.

The speed of a star in km/s, measured in a direction perpendicular to the line of sight from Earth to the star, is known as:

What fraction of the stars in the night sky are main-sequence stars?

The radius of a typical supergiant is how many times the radius of a typical white dwarf?

What is the intensity of sunlight per square meter reaching Saturn compared to the intensity at Earth's orbital distance?

Brown dwarfs give out energy due mainly to:

On the basis of the graph of absorption line strengths (in Figure 17-12), what is the spectral type of a star with the following spectral pattern: very strong He I lines, moderately strong H lines, weak Si III lines, and no Ca II, Fe II, or He II lines?

If Mercury is at 0.4 au, the Moon is at 1.0 au, and the inverse-square law holds, how much more light falls on a unit area of Mercury's surface than on an equivalent area of the Moon?