2007 Student Research Conference:
20th Annual Student Research Conference

Science

Using Cepheid Variable Stars and Other Standard Candles to Determine Extragalactic Distances
Ross A. Coleman
Dr. Ian Lindevald, Faculty Mentor

Distances to nearby stars are obtained through triangulation using observations at two different points in the earth's orbit around the sun. However, distances beyond several hundred light years cannot be determined through triangulation. Since the Milky Way galaxy alone is about 100,000 light-years across, triangulation is not a useful method for determining extragalactic distances. The luminosity of a star is its total power output. Since light intensity decreases with the square of distance, knowing a star's luminosity and measuring its intensity at earth gives its distance. Standard candles are special classes of stars for which luminosity can be precisely determined. For instance, measuring the period of a Cepheid variable star allows us to calculate its luminosity. Supernovae are standard candles that give distances even near the edge of the observable universe. The presentation focuses on the details of how standard candles, especially Cepheid variables, are used to determine extragalactic distances.

Keywords: astrophysics, standard candles, stellar distance, Cepheid variable, luminosity

Topic(s):Physics

Presentation Type: Oral Paper

Session: 13-4
Location: VH 1416
Time: 9:00 am

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