The Hertzsprung-Russell Diagram

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Plotting Stars on the HR Diagram

For this activity, you will plot stars on a simply HR Diagram, based on absolute magnitude and spectral type. There are two tables below, one of the brightest stars visible from Earth, and one of the nearest stars to Earth. Print out the HR Diagram template and then plot the stars from the first table in one color (say blue). Next plot the stars from the second table in a different color (say red). Once you have plotted all the stars note any patterns you see, and see if you can understand why or why not the patterns are there.

Note that there is some overlap between the two tables. For instance, the star Sirius A (being the brightest star visible from Earth and the 9th closest star to the Sun) is on both. You might want to use a third color to plot these. It likely will be cumbersome to put all the star names and/or designations on the chart (unless you have very small handwriting!). In fact, you don't really need them anyway, as all you are looking for are patterns. (After you have thought about the patterns, if any, and what may cause them, click here: Patterns.)

Note on the Spectral Types. The Sun is a G2V, meaning that it is a "G" star, subclass 2, and of a luminosity class V, signifying Main Sequence. Canopus is an A9II, meaning that it is an "A" star, subclass 9, with a luminosity class II, signifying a "bright" giant star. You also will notice some with designations such as "DA." These are white dwarf stars with no luminosity class ranking. Many of the spectral types end with a small letter such as "m" or "e." These are additional classifications indicating specific characteristics of the star's spectrum. You needed be concerned about them -- just consider the main spectral type. Now will you need the distances in light years, which are provided for your edification. Also, a few stars appear in both tables, and some stars do not have names per se, so their alphanumeric designation is provided instead.

Star data adapted from a list on Chris Nolan's Constellations site, originally from Norton's 2000.0, 18th edition.

The Brightest Stars:

The Nearest Stars

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