(a) Assume that a cloud of gas and dust is encountered along the line of sight for the data given in Table 24.2 and plotted in Problem 24.6. Assume also that the stellar number density found in Problem 24.6 is constant along the entire line of sight. Estimate the amount of extinction (in magnitudes) that is due to the cloud. Hint: How would the graph change if the cloud were not present? The cloud's presence may be revealed through reddening.
(b) If the density of gas and dust in the cloud leads to an extinction rate of 10 mag kpc−1, what is the length of the cloud along the line of sight?
Graphs of log10AM vs. m that demonstrate changes in slope and then resume the original slope at larger values of m are referred to as Wolf diagrams, after Maximilian Wolf (1863--1932), who first used them to explore the properties of interstellar clouds.