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The Variable Star Population in the Center of 47 Tuc as denned by HST Observations1

Published online by Cambridge University Press:  12 April 2016

Ronald L. Gilliland ,
Peter D. Edmonds ,
Larry Petro ,
Abhijit Saha  and
Michael Shara
Ronald L. Gilliland
Affiliation:
Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA
Peter D. Edmonds
Affiliation:
Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA
Larry Petro
Affiliation:
Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA
Abhijit Saha
Affiliation:
Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA
Michael Shara
Affiliation:
Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA

Abstract

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The high stellar densities at the centre of some globular clusters provide prolific breeding grounds for exotic stars, e.g., the 11 msec pulsars in 47 Tuc and numerous blue stragglers. The same high density of stars as viewed on the sky makes ground-based photometry problematic for variable star detection. Even a very few tight binaries can be of fundamental importance for the dynamic evolution of the cluster core. We present results of a continuous 40-hour sequence of U-band CCD exposures acquired with WF/PC on HST. The high spatial resolution coupled with a stable PSF allows nearly Poisson limited time series on some 20,000 stars. The 1000 second sampling and long coverage provide excellent sensitivity to W UMa and δ Scuti variations. Light curves are shown for selected variables and the relative frequencies of binary and variable stars are discussed.

Type
Part 2. Poster Papers
Information
International Astronomical Union Colloquium , Volume 155: Astrophysical Applications of Stellar Pulsation , 1995 , pp. 335 - 336
Copyright
Copyright © Astronomical Society of the Pacific 1995

Footnotes

1

Based on observations with the NASA/ESA Hubble Space Telescope obtained at the Space Telescope Science Institute, which is operated by Association of Universities for Research in Astronomy, Incorporated, under NASA contract NAS5-26555.

References

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