Exam 17: The Nature of the Stars

Radial velocity curves are plotted for a binary star system. The two curves cross when one star begins approaching and the other star begins receding, then cross again when they reverse, and then cross a third time when the first star again begins approaching. Which statement is TRUE about this set of curves?

Several optical glass filters are used to select specific portions of a star's light for photometry. Which of the following filters most closely matches the sensitivity of the eye, with peak wavelength sensitivity at about 550 nm? (I = infrared, B = blue, U = ultraviolet, V = visual)

What is the color of a star whose ratio of visual and blue apparent brightnesses, b_V/b_B, is 1.8?

In the Hertzsprung-Russell diagram of Figure 17-15a, which of the following is the correct sequence of stars in order of increasing temperature?

All of the statements comparing the Sun to the giant stars are true EXCEPT which of the following? (Refer to Figure 17-15a.)

What is the magnitude of a star that appears twice as bright as a 3.0 magnitude star?

Using the Hertzsprung-Russell diagram in Figure 17-15a. determine which type of star has the following characteristics: surface temperature of 10,000 K and luminosity 1/100 times that of the Sun.

The triple star system α Centauri has the largest known stellar parallax angle, namely 0.75 arcsec. How far is this star system from the Sun in light-years? (Careful with units!)

What effect does interstellar dust have on the apparent color of a star seen through the dust?

Betelgeuse and Barnard's star are both in the red portion of the H-R diagram as shown in Figure 17-15. What does this tell you about their relative sizes?

In a binary star system, each star is in an elliptical orbit with the:

How do the luminosities of main-sequence stars compare with those in luminosity class III?

Each of the following could cause a star to appear red EXCEPT ONE. Which is the EXCEPTION?

A star whose ratio of visual and blue apparent brightnesses is b_V/b_B = 5 (see Figure 17-9(in the text)) has a surface temperature of about:

The Hertzsprung-Russell diagram is a statistical plot of which of the following two stellar parameters?

What two quantities do we need to measure to calculate the tangential velocity of a star?

The color ratio b_B/b_U has the following values for four stars. Which value indicates the coolest surface temperature?

Figure 17-14 sketches a number of stellar properties: radius, temperature, chemical composition, spectral type, luminosity, and distance. It shows how these may be calculated from three measured quantities:

A particular star is found to have a very faint companion. When the spectrum of the companion is photographed and analyzed, it is found to contain absorption bands of the metal hydrides methane (CH₄) and ammonia (NH₃), :but no water (H₂O). Based on this information, the companion is a brown dwarf of spectral class

The intensity of sunlight per square meter reaching Venus is approximately what fraction of the intensity of sunlight at Earth's orbital distance?