In Cycle 17 we were awarded 121 orbits with HST to search for the faintest stellar populations (the coolest white dwarfs, the lowest mass main sequence stars and possibly the brown dwarfs) in 47 Tucanae. It took 10 months to secure all the data with exquisite care taken to minimize the effects of charge transfer and saturation spikes. The ACS stared at a single field for all 121 orbits but the roll angle of the telescope was varied through 180 degrees for the associated parallel fields observed with WFC3. Archival data were employed to proper motion clean the images allowing virtually complete separation of field stars and those in the background Small Magellanic Cloud from those in the cluster. In this poster, we present the resultant color-magnitude diagram for this important cluster which is a proxy for the Galactic bulge. A rich white dwarf cooling sequence is revealed which will be used to determine a cooling age for the cluster for comparison with the turnoff age (see associated poster by A. Dotter et al.). Multicolor data in other ACS filters as well as four filters with WFC3 are used to examine the spectral energy distributions of the cluster white dwarfs.
American Astronomical Society Meeting Abstracts #217
- Pub Date:
- January 2011