The Cooling of Old White Dwarfs in 47 Tucanae
arXiv:2507.22046 · doi:10.1093/mnras/stag1024
Abstract
We analyse the cooling of white dwarfs in the globular cluster 47 Tucanae (47 Tuc) using deep observations from the Hubble Space Telescope that resolve the white dwarf cooling sequence to late enough cooling times that the envelope has become convectively coupled to the core. At these late times, the thickness of the outer H envelope is an important consideration in modelling the cooling. Using the stellar evolution software Modules for Experiments in Stellar Astrophysics, we create a suite of white dwarf cooling models for different thicknesses of the H envelope and different white dwarf masses. An unbinned likelihood analysis is performed to compare the cooling models to the observations in order to constrain the values of these key parameters. We find that thicker H envelopes are preferred, with the best-fitting models reproducing the observed cumulative 47 Tuc white dwarf luminosity functions well.
23 pages, 13 figures, published in MNRAS
References in corpus (12)
- Modules for Experiments in Stellar Astrophysics (MESA)
- Modules for Experiments in Stellar Astrophysics (MESA): Pulsating Variable Stars, Rotation, Convective Boundaries, and Energy Conservation
- Gaia Early Data Release 3: Photometric content and validation
- Modules for Experiments in Stellar Astrophysics (MESA): Time-Dependent Convection, Energy Conservation, Automatic Differentiation, and Infrastructure
- Updated Electron-Conduction Opacities: The Impact on Low-Mass Stellar Models
- On the Spectral Evolution of Hot White Dwarf Stars. I. A Detailed Model-Atmosphere Analysis of Hot White Dwarfs from SDSS DR12
- Found: The missing blue opacity in atmosphere models of cool hydrogen white dwarfs
- YBC, a stellar bolometric corrections database with variable extinction coefficients: an application to PARSEC isochrones
- The WISE Extended Source Catalogue (WXSC) I: The 100 Largest Galaxies
- New Conductive Opacities for White Dwarf Envelopes
- Electron conduction opacities at the transition between moderate and strong degeneracy: Uncertainties and impact on stellar models
- The Onset of Convective Coupling and Freezing in the White Dwarfs of 47 Tucanae