Light Curves and Period Changes for Type II Cepheids in the Globular Cluster M13 (Abstract)
Volume 43 number 2 (2015)
- Horace A. Smith
- Michigan State University, Department of Physics and Astronomy, Bio-Physical Sciences Building, 567 Wilson Road, East Lansing, MI 48824; smith@pa.msu.edu
- Mary Anderson
- P. O. Box 300, North Highlands, CA 95660; address email to H. A. Smith, smith@pa.msu.edu
- Wayne Osborn
- Central Michigan University and Yerkes Observatory, 118 Eagle Pointe Drive, Unit C, Delevan, WI 53115; wayne.osborn@cmich.edu
- Andrew Layden
- Bowling Green State University, Department of Physics and Astronomy, 104 Overman Hall, Bowling Green, OH 43403; laydena@bgsu.edu
- Grzegorz Kopacki
- Instytut Astronomiczny, Uniwersytet Wrocławski, Kopernika 11, 51-622Wrocław, Poland; kopacki@astro.uni.wroc.pl
- Barton Pritzl
- Department of Physics and Astronomy, University of Wisconsin Oshkosh, Oshkosh, WI 54901; pritzlb@uwosh.edu
- Andrew Kelley
- Bowling Green State University, Department of Physics and Astronomy, 104 Overman Hall, Bowling Green, OH 43403
- Keith McBride
- Bowling Green State University, Department of Physics and Astronomy, 104 Overman Hall, Bowling Green, OH 43403
- Michael Alexander
- Lehigh University, Department of Physics, 16 Memorial Drive E., Bethlehem, PA 18015; mia313@lehigh.edu
- Charles Kuehn
- University of Sydney, 44 Rosehill Street, Redfern, NSW 2042, Australia; kuehn@physics.usyd.edu.au
- Aron Kilian
- Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824
- Eric King
- Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824
- David Carbajal
- Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824
- R. Lustig
- Department of Physics and Astronomy, Macalester College, Saint Paul, MN 55105
- Nathan De Lee
- University of Nebraska at Kearney, 2401 11th Avenue, Kearney, NE 68849
Abstract
(Abstract only) B, V, and Cousins I-band light curves have been observed for the type II Cepheids V1, V2, and V6 in the globular cluster M13. These are relatively short period, BL Her-type Cepheids, with periods of 1.5, 5.1, and 2.1 days, respectively. Additional observations of V2 have been obtained from early photographic plates in the Yerkes Observatory archive. Long term period changes of these Cepheids have been determined by combining recent photometry with earlier observations that now extend back for more than a century. The observed period changes for V1, V2, and V6 are compared with the predictions of stellar evolution theory, under the assumption that the progenitors of the Cepheids were stars that at one time were on the blue horizontal branch.