2010/05/01 by E. Garcı́a–Berro, Enrique García-Berro, Santiago Torres +14 · 244 citations
Physics and Astronomy · #Astronomy #Astronomy and Astrophysical Research #Astrophysics #Astrophysics and Star Formation Studies #Main sequence #Open cluster #Physics #Stars #Stellar, planetary, and galactic studies #White dwarf #astro-ph.SR
paper · pdf · doi:10.1038/nature09045
published in Nature 465(7295), 194-196 (Nature Portfolio) · 3 pages, 2 figures, published in Nature
openalex publication_date 2010/05/01 · arxiv created 2010/05/13 · arxiv updated 2015/05/19 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
NGC 6791 is a well studied open cluster1 that it is so close to us that can be imaged down to very faint luminosities. The main sequence turn-off age (~8 Gyr) and the age derived from the termination of the white dwarf cooling sequence (~6 Gyr) are significantly different. One possible explanation is that as white dwarfs cool, one of the ashes of helium burning, 22Ne, sinks in the deep interior of these stars. At lower temperatures, white dwarfs are expected to crystallise and phase separation of the main constituents of the core of a typical white dwarf, 12C and 16O, is expected to occur. This sequence of events is expected to introduce significant delays in the cooling times, but has not hitherto been proven. Here we report that, as theoretically anticipated, physical separation processes occur in the cores of white dwarfs, solving the age discrepancy for NGC 6791.