Hubble Space Telescope Observations of the White Dwarf Cooling Sequence of M4

  title={Hubble Space Telescope Observations of the White Dwarf Cooling Sequence of M4},
  author={Brad M S Hansen and Harvey B. Richer and Gregory G. Fahlman and Peter B. Stetson and James Philip Brewer and Thayne M. Currie and Brad K. Gibson and Rodrigo A. Ibata and Roded Shara},
  journal={Astrophysical Journal Supplement Series},
We investigate in detail the white dwarf cooling sequence of the globular cluster Messier 4. In particular, we study the influence of various systematic uncertainties, both observational and theoretical, on the determination of the cluster age from the white dwarf cooling sequence. These include uncertainties in the distance to the cluster and the extinction along the line of sight, as well as the white dwarf mass, envelope, and core compositions and the white dwarf-main-sequence mass relation… 
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