H-R Diagram Patterns


The twelfth conceptual objective, “I can explain how astronomers use the Hertzsprung-Russel diagram to study properties of stars”, has been a topic of discussion in class as of late. The H-R diagram is a graphical tool that astronomers use to classify stars according to their luminosity, spectral type, color, temperature and evolutionary stage. In order to analyze the relationship between the spectral type and luminosity of a star, Ejnar Hertzsprung and Henry Norris Russell came up with the H-R diagram. They started by making graphs of stellar properties. One axis of the graph consists of stellar luminosity while the other axis is the spectral type. Ultimately, these graphs paved the way toward a fundamental pattern among stars. The H-R diagram now serves as a fundamental way to research and study the properties of stars. In class, we exercised this concept in the Lecture-Tutorial book. In the section titled, “H-R Diagram”, in the Lecture-Tutorial book, we were given an example star and we were asked to determine the stars’ spectral type, temperature, absolute magnitude and luminosity of the star only using the given H-R diagram. We then had to compare the properties of one star to the others. This tutorial has given me a full understanding of the H-R diagram. The clear layout of the H-R diagram graphs makes the study of stars’ properties simplistic.

The article I chose, “Massive Survey Makes Sense of the Diversity of Quasars”, discusses the relationships of a variety of stars observed in the sky. Quasars are similar to stars but are light from rapidly accreting, super massive black holes. Quasars come in random forms, causing astronomers to further investigate them. This specific study observed over 20,000 quasars. Eventually, a pattern was noticed. The H-R diagram was used to indicate a relationship among these quasars. All 20,000 of the observed quasars fit into a pattern, much like the main sequence stars. Essentially, there is a main sequence of quasars. This indicates that the H-R diagram is consistent and accurate. The diagram consisting of quasars is almost identical to the main sequence stars in the H-R diagram.

Figure 1 in the paper. The graph relates orientation to the black hole's consumption efficiency. Data points represent the 20,000 quasars from the Sloan Digital Sky Survey.  H-R diagram, with over 22,000 stars plotted.

The quasars discussed in this article compares to the stars we discussed in class. An unique pattern exists among main sequence stars on the H-R diagram and quasars. This article clearly demonstrates the twelfth conceptual objective by comparing the main sequence stars to studied quasars. The pattern that exists among the main sequence stars can be directly compared to the pattern that exists among the quasars. This article was very interesting to me, as it allowed me to get a better understanding of how the H-R diagram is used to classify stars, and also quasars. The correlation between a stars’ luminosity and surface temperature is clearly portrayed on the H-R diagram.




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