Galactic fountains are an important way to explain _____
a. the distribution of metals in and above the plane of the galactic disk
b. the nature of dark matter
c. the formation of the galactic disk from the first stages of our galaxy
d. the generation and support of spiral density waves
e. why the spiral arms are active sites of star formation
a
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Which best describes the appearance of an asteroid?
a. spherical in shape and covered with craters b. spherical in shape with a volcanic surface c. irregular in shape and covered with craters d. irregular in shape with a volcanic surface e. spherical in shape and smooth, dusty surface
A star is observed with a surface temperature of 3,000 K and a luminosity of 10?2 solar. What is the approximate mass of this star?
A) 0.5 Msun B) 0.9 Msun C) 0.2 Msun D) The mass cannot be determined.
What is the explanation for the pattern of granulation seen on the visible surface of the Sun?
a. The granules form the base of a circulation pattern that extends from the photosphere to the outer corona. b. The granules are regions of nuclear energy generation in the Sun's photosphere. c. Each granule contains a strong magnetic field, which compresses and heats the gas underneath it. d. The granules are the tops of hot gas that have risen from the Sun's convective zone.
In an X-ray diffraction experiment using X-rays of ? = 0.500 × 10?10 m, a first-order maximum occurred at 5.00°. Find the crystal plane spacing.
A. 2.87 × 10?10 m B. 1.36 × 10?10 m C. 6.24 × 10?9 m D. 1.93 × 10?9 m E. 5.74 × 10?9 m