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Chapter 12: Measuring the Properties of Stars
Distances to the Stars
If you observe something from one position and then change your position, nearby objects will appear to move with respect to distant objects. This observation, or method of judging, is called parallax. (For a number of differenty methods in finding distances to objects in the universe check this site: http://www.astro.ucla.edu/~wright/distance.htm)
Study the materials on this page and the links in it and propose a method using parallax to measure the distance from where you are standing to a visible object.
Visit the Distances to the Stars web site
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Astrometry via Hipparcos
The European Space Agency's "Hipparcos" satellite provided important astrometric data.
Use ESA's Hipparcos site to answer the following: 1) Hipparcos provided data for at least three different categories of stars. Name these and summarize Hipparcos' contribution in each case. (Hint: Go to the Education page.) 2) How did amateurs help the Hipparcos mission? (Hint: A link from the Education page.)
Visit the Hipparcos Space Astrometry Mission web site
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Astrometry via GAIA
Now that the Hipparcos satellite has completed its mission, the European Space Agency is making plans to take the next step in astrometry.
Report on the GAIA mission. Specifically: 1) GAIA is an acronym for what? 2) What is the present status of plans for GAIA?
Visit the The GAIA Homepage web site
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H-R Diagram of the Sun
The H-R diagram is a very useful tool in understanding the life cycle of a star. In the case of our Sun it can tell us something about the future of the Earth, too.
Describe what will happen to the Sun from the time it runs out of hydrogen until its helium is suddenly fused to carbon.
Visit the The Future of the Sun web site
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Multiple Star Systems
More than half of what appear as single stars in the night sky are really multiple star systems. A binary star system is the term used when stars in multiple star systems are gravitationally linked.
Examine the materials here and distinguish among visual, spectroscopic, and eclipsing binary systems. (Hint: Use the "Next" button several times.)
Visit the Multiple Star Systems web site
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