Abstract Details
| Name: Laksh Gupta Affiliation: Ahmedabad University Conference ID: ASI2025_269 Title : Study of white dwarfs in NGC2808 using Near-Ultraviolent and optical data from the Hubble Space Telescope Authors and Co-Authors : Author: Laksh Gupta Co-author(s): Samyaday Choudhury, Annalisa Calamida, Christian Johnson, Maurizio Salaris, Dominico Nardiello Abstract Type : Poster Abstract Category : Stars, Interstellar Medium, and Astrochemistry in Milky Way Abstract : NGC2808 is a highly unusual Galactic globular cluster (GC) that supposedly underwent more than one episode of star formation and hosts distinct stellar sub-populations and a significant number of binaries. This study analyzes the white dwarf stars (WDs ~ 500 stars) in NGC2808 using deep near-ultraviolet and optical data (F275W and F336W filter systems) from the Hubble Space Telescope UV Globular Cluster Survey (HUGS). Recently discovered slowly cooling WDs (SCWDs) in only two GCs - M13 and NGC6752 have greatly impacted our understanding of WDs as cosmic chronometers, given that it contradicts the canonical definition of WDs as objects that simply cool. To investigate this, we analyzed the color-magnitude diagrams (CMDs) of NGC2808 using various combinations of filters. We performed star count-crossing time analysis to estimate the theoretical star counts of main sequence turn-off and WDs stars by comparing the completeness-corrected observed counts. We used various isochrones, evolutionary tracks, and BASTI CO-core/H-envelope 0.54 M☉ cooling models of WDs and adopted reddening and distance modulus values from the literature to find the crossing times of evolutionary phases. We inferred a significant excess of WDs from the analysis and WD luminosity function plots, which suggests that these could be slowly cooling Hydrogen envelope WDs or He-core WDs in the cluster. |