![]() ![]() It’s not mathematically exact-there is a wide range of variation-but it’s not a bad overall rule. Typically, if we have bigger bones, we have more flesh to fill out our larger frame. This makes sense if you are familiar with the structure of human beings. Generally speaking, taller human beings weigh more, whereas shorter ones weigh less. We can conclude from this graph that human height and weight are related. Most points lie along a “main sequence” representing most people, but there are a few exceptions. The plot of the heights and weights of a representative group of human beings. Most points fall along a sequence that goes from the upper left to the lower right. Notice that humans are not randomly distributed in the graph. In the way we have chosen to present our data, height increases upward, whereas weight increases to the left. Such a plot is shown in Figure 1and it has some interesting features. For example, you might plot the heights of a large sample of humans against their weights (which is a measure of their mass). ![]() If you want to understand humans by comparing and contrasting their characteristics-without assuming any previous knowledge of these strange creatures-you could try to determine which characteristics lead you in a fruitful direction. To help understand what sorts of relationships might be found, let’s look briefly at a range of data about human beings. Measure the light curves and Doppler shifts for eclipsing binary stars. Measure the way a star’s light is blocked by the Moon.Ģ. Measure the period and radial velocity curves of spectroscopic binary stars.ġ. Measure the Doppler shift in the spectrum. Measure the apparent brightness and compensate for distance. Measure the spectrum and get the spectral type.ĭetermine which lines are present in the spectrum. When the characteristics of large numbers of stars were measured at the beginning of the twentieth century, astronomers were able to begin a deeper search for patterns and relationships in these data. We have also given an example of a relationship between two of these characteristics in the mass-luminosity relation. In this chapter and Analyzing Starlight, we described some of the characteristics by which we might classify stars and how those are measured. Discuss the physical properties of most stars found at different locations on the H–R diagram, such as radius, and for main sequence stars, mass.Identify the physical characteristics of stars that are used to create an H–R diagram, and describe how those characteristics vary among groups of stars.By the end of this section, you will be able to:
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