Exam 17: The Nature of the Stars

What is the mass of a main-sequence star that has a luminosity 1000 times greater than that of the Sun? (See Figure 17-22.(in the text))

A red filter passes light at the long wavelength end of the visible spectrum as shown in Figure 17-7. Star 1 and Star 2 are viewed through identical red filters, and Star 1 appears brighter through the filter than does Star 2. What can be determined from this information?

Proxima Centauri is the nearest star beyond the Sun. Its distance is roughly:

If a nearby star shows a parallax of 0.5 arcsec, what is its distance from Earth in parsecs?

The star Ross 128 has a parallax of 0.301 arcsec, a radial velocity of 13 km/s, and a proper motion of 1.40 arcsec per year. At what total velocity does Ross 128 travel through space, relative to the Sun?

A particular star has an absolute magnitude of + 12 and a spectral class of A5. Using Figure 17-18, how would this star be classified?

Which two vital parameters are used to describe the systematics of a group of stars (e.g., cluster) in the Hertzsprung-Russell diagram?

What proportion of visible stars in the night sky are multiple-star systems?

Light intensity variations are detected from a star in which the intensity remains essentially constant, except for the periodic, short, and regular increases and decreases by a fixed amount. What is the most likely explanation for this observation?

Brown dwarfs of spectral type T have surface temperatures below 1300 K. We are also familiar with a group of objects that emit infrared radiation at even lower temperatures, typically a few hundred kelvins. These objects are called:

On the basis of the graph of absorption line strengths in spectra of stars presented in Figure 17-12, what is the spectral type of a star with the following spectral pattern: very strong H, weaker Mg II and Si II, and no He I or Ca II lines?

By studying the radial velocity curves of two visible stars in an edge-on binary system, we determine that the mass of Star A is 3 times the mass of Star B. We also observe their period to be 8 years and the semimajor axis of their relative orbit to be 4 au. What are the masses of these stars?

A particular star has a radius half that of the Sun and a luminosity equal to 60% of that of the Sun. What is the star's surface temperature? (See Box 17-4.) The surface temperature of the Sun is 5800 K.

One star has a spectral-luminosity class of B5 V (main sequence) and the other has a spectral-luminosity class of B5 Ia (supergiant). What difference do we see in the spectra of these two stars and why?

A particular star is equally bright when viewed through a blue filter and a yellow filter. What is the approximate surface temperature of this star? (See Figure 17-9.(in the text))

In the spectral sequence of star types, each category has been divided into 10 intervals. The Sun is classified as:

A particular star is brighter seen through a blue filter than through a yellow filter. Which of the following surface temperatures is possible for this star? (See Figure 17-9.(in the text))

Which molecule produces the spectral absorption bands that are prominent in the spectrum of the cool M-type star in Figure 17-12?

If two stars of unequal mass orbit each other under mutual attraction in circular orbits, what will be the location of the center of these orbits? (See Figure 17-21.(in the text))

In Figure 17-15, both Regulus and Mira are about 100 times as luminous as the Sun. What is the primary source of their radiant energy?