Several studies have laid groundwork for the fact that the populations of binary systems and blue straggler stars (BSSs) are related, particularly in globular clusters (GCs). Formation channels proposed for BSSs, stars which appear to be more massive and hotter than the rest of the population, can be traced at least partially back to the evolution of binary systems. Furthermore, Milone et al. 2012 found that both BSSs and binaries anti-correlate with the mass of their host cluster, in addition to a correlation between the binary fraction and BSSs frequency in cluster cores. This connection, although apparent, has yet to be directly quantified. In this thesis, I utilized HST observations, in the filters F814W and F275W, to derive high precision photometry and astrometry of the globular cluster NGC 6101, in order to construct mass functions (MFs) as a new approach to remedy this situation. In relating these MFs with each other, a measurable connection between the binary population and BSSs can be determined. Three methods to calculate this were employed, involving estimates for the overall average number of binaries and BSSs, as well as through extrapolating the binary MF out to the range of the BSS MF and doing a bin by bin comparison. All methods found that roughly 10% of binaries may have evolved into BSSs over time. As such, this has provided a meaningful inquiry into the BSS-binary connection for NGC 6101. Expanding this approach for a larger dataset of GCs, as well as comparison to statistical simulations, could then be used to examine how the BSS-binary populations change with respect to GC parameters.
Several studies have laid groundwork for the fact that the populations of binary systems and blue straggler stars (BSSs) are related, particularly in globular clusters (GCs). Formation channels proposed for BSSs, stars which appear to be more massive and hotter than the rest of the population, can be traced at least partially back to the evolution of binary systems. Furthermore, Milone et al. 2012 found that both BSSs and binaries anti-correlate with the mass of their host cluster, in addition to a correlation between the binary fraction and BSSs frequency in cluster cores. This connection, although apparent, has yet to be directly quantified. In this thesis, I utilized HST observations, in the filters F814W and F275W, to derive high precision photometry and astrometry of the globular cluster NGC 6101, in order to construct mass functions (MFs) as a new approach to remedy this situation. In relating these MFs with each other, a measurable connection between the binary population and BSSs can be determined. Three methods to calculate this were employed, involving estimates for the overall average number of binaries and BSSs, as well as through extrapolating the binary MF out to the range of the BSS MF and doing a bin by bin comparison. All methods found that roughly 10% of binaries may have evolved into BSSs over time. As such, this has provided a meaningful inquiry into the BSS-binary connection for NGC 6101. Expanding this approach for a larger dataset of GCs, as well as comparison to statistical simulations, could then be used to examine how the BSS-binary populations change with respect to GC parameters.
The relationship between binaries and blue stragglers: a photometric analysis of NGC 6101
GRIMALDI, ISABELLA MARIA
2023/2024
Abstract
Several studies have laid groundwork for the fact that the populations of binary systems and blue straggler stars (BSSs) are related, particularly in globular clusters (GCs). Formation channels proposed for BSSs, stars which appear to be more massive and hotter than the rest of the population, can be traced at least partially back to the evolution of binary systems. Furthermore, Milone et al. 2012 found that both BSSs and binaries anti-correlate with the mass of their host cluster, in addition to a correlation between the binary fraction and BSSs frequency in cluster cores. This connection, although apparent, has yet to be directly quantified. In this thesis, I utilized HST observations, in the filters F814W and F275W, to derive high precision photometry and astrometry of the globular cluster NGC 6101, in order to construct mass functions (MFs) as a new approach to remedy this situation. In relating these MFs with each other, a measurable connection between the binary population and BSSs can be determined. Three methods to calculate this were employed, involving estimates for the overall average number of binaries and BSSs, as well as through extrapolating the binary MF out to the range of the BSS MF and doing a bin by bin comparison. All methods found that roughly 10% of binaries may have evolved into BSSs over time. As such, this has provided a meaningful inquiry into the BSS-binary connection for NGC 6101. Expanding this approach for a larger dataset of GCs, as well as comparison to statistical simulations, could then be used to examine how the BSS-binary populations change with respect to GC parameters.File | Dimensione | Formato | |
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https://hdl.handle.net/20.500.12608/79647