Astronomy HW #21

Which of the following would NOT be useful in constructing a Hertzsprung-Russell (H-R) diagram?

Why are the most common stars among the most difficult to observe?

An H-R diagram is a plot of which two stellar properties?

Why does the spectroscopic parallax method only work for main sequence stars?

Three M-class stars are identified as main-sequence, giant, and supergiant, respectively. In which physical property do they differ?

What is the full spectral classification of the Sun?

If you could make an entire main sequence of stars, all at the same time, which ones would die first?

Low-mass stars have much longer lifetimes than high-mass stars. Which stellar property is a direct cause of this difference?

A high-mass star has more "fuel" than a low-mass star. Which lives longer? Why?

What property of stars can be measured only by using binary-star systems?

Which of the following does NOT increase as mass increases for main sequence stars?

According to Figure 10.12 in the textbook (H-R Diagram of Well-Known Stars), Barnard's star must be

Compared with a star of absolute magnitude -2 at a distance of 100 pc, a star of absolute magnitude 5 at a distance of 10 pc will appear

The mass of a star may be determined

According to Figures 10.19 in the textbook (Stellar Masses) and 10.20 in the textbook (Stellar Mass Distribution), compared to the Sun, most stars are

From a distance of 1 parsec, the angular size of Earth's orbit would be

Stars of spectral class M do not show strong lines of hydrogen in their spectra because

The radius of a star can be indirectly determined if the star's distance and luminosity are known.

In a spectroscopic binary, the orbital motion of the component stars appears as variations in the overall apparent brightness of the system.

There are no billion-year-old main-sequence O- or B-type stars

Star A appears brighter than star B, as seen from Earth. Therefore, star A must be closer to Earth than star B.

A star of apparent magnitude +5 looks brighter than one of apparent magnitude +2.

Red giants are very bright because they are extremely hot.

Astronomers can distinguish between main-sequence and giant stars purely by spectroscopic means.

Cool stars can be very luminous if they are very

Pluto's apparent magnitude is approximately 14. According to Figure10.6 in the textbook (Apparent Magnitude), Pluto can be seen