Globular Cluster Variable Stars—Atlas and Coordinate Improvement using AAVSOnet Telescopes (Abstract)

Volume 43 number 2 (2015)

Doug Welch

Department of Physics and Astronomy, McMaster University, Hamilton, ON L8S 4M1, Canada; welch@physics.mcmaster.ca

Arne Henden

106 Hawkins Pond Road, Center Harbor, NH 03226; arne@aavso.org

Taylor Bell

Saskatoon, SK, Canada; taylor.bell@usask.ca

Cissy Suen

Address correspondence to D. Welch, Department of Physics and Astronomy, McMaster University, Hamilton, ON L8S 4M1, Canada; welch@physics.mcmaster.ca

Ian Fare

Address correspondence to D. Welch, Department of Physics and Astronomy, McMaster University, Hamilton, ON L8S 4M1, Canada; welch@physics.mcmaster.ca

Alison Sills

Address correspondence to D. Welch, Department of Physics and Astronomy, McMaster University, Hamilton, ON L8S 4M1, Canada; welch@physics.mcmaster.ca

Abstract

(Abstract only) The variable stars of globular clusters have played and continue to play a significant role in our understanding of certain classes of variable stars. Since all stars associated with a cluster have the same age, metallicity, distance, and usually very similar (if not identical) reddenings, such variables can produce uniquely powerful constraints on where certain types of pulsation behaviors are excited. Advanced amateur astronomers are increasingly well-positioned to provide long-term CCD monitoring of globular cluster variable stars but are hampered by a long history of poor or inaccessible finder charts and coordinates. Many of variable-rich clusters have published photographic finder charts taken in relatively poor seeing with blue-sensitive photographic plates. While useful signal-to-noise ratios are relatively straightforward to achieve for RR Lyrae, Type 2 Cepheids, and red giant variables, correct identification remains a difficult issue—particularly when images are taken at V or longer wavelengths. We describe the project and report its progress using the OC61, TMO61, and SRO telescopes of AAVSOnet after the first year of image acquisition, and demonstrate several of the data products being developed for globular cluster variables