Kristin A. Woodley, Ryan Goldsbury, Jason Kalirai, Harvey Richer, Pier-Emmanuel Tremblay, Jay Anderson, Pier Bergeron, Aaron Dotter, Lisa Esteves, Greg Fahlman, Brad Hansen, Jeremy Heyl, Jarrod Hurley, R. Michael Rich, Michael Shara, Peter Stetson
We present a new distance determination to the Galactic globular cluster 47
Tucanae by fitting the spectral energy distributions of its white dwarfs to
pure hydrogen atmosphere white dwarf models. Our photometric dataset is
obtained from a 121 orbit Hubble Space Telescope program using the Wide Field
Camera 3 UVIS/IR channels, capturing F390W, F606W, F110W, and F160W images.
These images cover more than 60 square arcmins and extend over a radial range
of 5-13.7 arcmin (6.5-17.9 pc) within the globular cluster. Using a likelihood
analysis, we obtain a best fitting unreddened distance modulus of (m -
M)o=13.36+/-0.02+/-0.06 corresponding to a distance of 4.70+/-0.04+/-0.13 kpc,
where the first error is random and the second is systematic. We also search
the white dwarf photometry for infrared excess in the F160W filter, indicative
of debris disks or low mass companions, and find no convincing cases within our
sample.
View original:
http://arxiv.org/abs/1112.1425
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