A Search for Helium-Core White Dwarfs in the Globular Cluster 47 Tuc
Abstract
We report preliminary results of a search for helium-core white dwarfs (He WDs) in the globular cluster 47 Tuc. These low-mass white dwarfs are understood to form in binary systems in which a star's evolution is interrupted as it climbs the red giant branch. As such, He WDs can provide a window into the binary star populations in globular clusters. Using WFC3/UVIS data from the Hubble Space Telescope in two filters, F300X and F390W, we construct a color-magnitude diagram and begin by selecting a subset of the best-measured stars in the cluster. From this cleaned diagram we isolate a population of 50 candidate low-mass white dwarfs. Comparing the radial distribution of these stars to the radial distributions of other populations of known mass in 47 Tuc, we show that the He WDs are more centrally concentrated than can be explained if they are single stars. This makes 47 Tuc the third cluster in which a significant population of probable binary stars containing He WDs has been identified.
- Publication:
-
American Astronomical Society Meeting Abstracts #234
- Pub Date:
- June 2019
- Bibcode:
- 2019AAS...23432206D