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A Search for Metal-Poor Stars in the Halo of the Milky Way

Research output: Thesis › Master's Thesis

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A Search for Metal-Poor Stars in the Halo of the Milky Way. / Mohammed, Aruba.
Lancaster University, 2023. 84 p.

Research output: Thesis › Master's Thesis

Harvard

Mohammed, A 2023, 'A Search for Metal-Poor Stars in the Halo of the Milky Way', Masters by Research, Lancaster University. https://doi.org/10.17635/lancaster/thesis/1931

APA

Mohammed, A. (2023). A Search for Metal-Poor Stars in the Halo of the Milky Way. [Master's Thesis, Lancaster University]. Lancaster University. https://doi.org/10.17635/lancaster/thesis/1931

Vancouver

Mohammed A. A Search for Metal-Poor Stars in the Halo of the Milky Way. Lancaster University, 2023. 84 p. doi: 10.17635/lancaster/thesis/1931

Author

Mohammed, Aruba. / A Search for Metal-Poor Stars in the Halo of the Milky Way. Lancaster University, 2023. 84 p.

Bibtex

@mastersthesis{f1dcb71c6f57462f9c714748a73ad4d5,
title = "A Search for Metal-Poor Stars in the Halo of the Milky Way",
abstract = "Metal-poor stars are essential in developing an understanding of the nature ofthe early Universe and the first stars.This study is based on the investigation by Jenkins et al. (2019), which usedthe data that Sobral et al. (2017) gathered from the COSMOS field using theIsaac Newton Telescope (INT) between 2013 and 2015, for the CALYMHA survey.The catalogue contained 123,505 sources and the aim of the investigation was todiscover Pop III stars or their direct descendants.The goal of this research was the same; to discover potential metal-poor candidate stars in the halo of the Milky Way, with an emphasis on extremely metal-poor (EMP: [Fe/H] Using the same catalogue of sources as Jenkins et al. (2019), I was able toinitially adopt and improve their approach to identify 165 metal-poor candidates.I used 102 theoretical spectra from the Pollux database with complete integer metallicities ([Fe/H]) of 0 to -5 to compute magnitude values for multiplefilters: NB392, g, u and i, which were then used to estimate metallicities of the165 candidate metal-poor stars via colour-colour plots and metallicity heatmaps.16 EMP and 38 UMP candidate stars were identified. The correlation between temperature and g-i values was also explored and used to classify the 165candidates. The distance of the stars with a [Fe/H] < -3 was estimated based onapproximations and I found that 41 UMP and EMP candidates sit within 66kpc,and therefore can be reasonably approximated to sit within the Milky Way Halo.Number densities for the candidate F,G and K-type stars identified in thisstudy are (1.50±0.81)×10−13 pc−3, (7.64±1.89) ×10−12 pc−3 and (1.91±0.34) × 10−9 pc−3 respectively, which follows the pattern reported in literature. Finally, I created a metallicity distribution function (MDF) for the candidate stars which follows the predicted MDF and F-type stars are shown to peak around [Fe/H] = -1.5 which is close to the literature value of [Fe/H] = -1.6.",
keywords = "astrophysics, metal poor stars, stars, space, halo, milky way, galaxy",
author = "Aruba Mohammed",
year = "2023",
doi = "10.17635/lancaster/thesis/1931",
language = "English",
publisher = "Lancaster University",
school = "Lancaster University",

}

RIS

TY - THES

T1 - A Search for Metal-Poor Stars in the Halo of the Milky Way

AU - Mohammed, Aruba

PY - 2023

Y1 - 2023

N2 - Metal-poor stars are essential in developing an understanding of the nature ofthe early Universe and the first stars.This study is based on the investigation by Jenkins et al. (2019), which usedthe data that Sobral et al. (2017) gathered from the COSMOS field using theIsaac Newton Telescope (INT) between 2013 and 2015, for the CALYMHA survey.The catalogue contained 123,505 sources and the aim of the investigation was todiscover Pop III stars or their direct descendants.The goal of this research was the same; to discover potential metal-poor candidate stars in the halo of the Milky Way, with an emphasis on extremely metal-poor (EMP: [Fe/H] Using the same catalogue of sources as Jenkins et al. (2019), I was able toinitially adopt and improve their approach to identify 165 metal-poor candidates.I used 102 theoretical spectra from the Pollux database with complete integer metallicities ([Fe/H]) of 0 to -5 to compute magnitude values for multiplefilters: NB392, g, u and i, which were then used to estimate metallicities of the165 candidate metal-poor stars via colour-colour plots and metallicity heatmaps.16 EMP and 38 UMP candidate stars were identified. The correlation between temperature and g-i values was also explored and used to classify the 165candidates. The distance of the stars with a [Fe/H] < -3 was estimated based onapproximations and I found that 41 UMP and EMP candidates sit within 66kpc,and therefore can be reasonably approximated to sit within the Milky Way Halo.Number densities for the candidate F,G and K-type stars identified in thisstudy are (1.50±0.81)×10−13 pc−3, (7.64±1.89) ×10−12 pc−3 and (1.91±0.34) × 10−9 pc−3 respectively, which follows the pattern reported in literature. Finally, I created a metallicity distribution function (MDF) for the candidate stars which follows the predicted MDF and F-type stars are shown to peak around [Fe/H] = -1.5 which is close to the literature value of [Fe/H] = -1.6.

AB - Metal-poor stars are essential in developing an understanding of the nature ofthe early Universe and the first stars.This study is based on the investigation by Jenkins et al. (2019), which usedthe data that Sobral et al. (2017) gathered from the COSMOS field using theIsaac Newton Telescope (INT) between 2013 and 2015, for the CALYMHA survey.The catalogue contained 123,505 sources and the aim of the investigation was todiscover Pop III stars or their direct descendants.The goal of this research was the same; to discover potential metal-poor candidate stars in the halo of the Milky Way, with an emphasis on extremely metal-poor (EMP: [Fe/H] Using the same catalogue of sources as Jenkins et al. (2019), I was able toinitially adopt and improve their approach to identify 165 metal-poor candidates.I used 102 theoretical spectra from the Pollux database with complete integer metallicities ([Fe/H]) of 0 to -5 to compute magnitude values for multiplefilters: NB392, g, u and i, which were then used to estimate metallicities of the165 candidate metal-poor stars via colour-colour plots and metallicity heatmaps.16 EMP and 38 UMP candidate stars were identified. The correlation between temperature and g-i values was also explored and used to classify the 165candidates. The distance of the stars with a [Fe/H] < -3 was estimated based onapproximations and I found that 41 UMP and EMP candidates sit within 66kpc,and therefore can be reasonably approximated to sit within the Milky Way Halo.Number densities for the candidate F,G and K-type stars identified in thisstudy are (1.50±0.81)×10−13 pc−3, (7.64±1.89) ×10−12 pc−3 and (1.91±0.34) × 10−9 pc−3 respectively, which follows the pattern reported in literature. Finally, I created a metallicity distribution function (MDF) for the candidate stars which follows the predicted MDF and F-type stars are shown to peak around [Fe/H] = -1.5 which is close to the literature value of [Fe/H] = -1.6.

KW - astrophysics

KW - metal poor stars

KW - stars

KW - space

KW - halo

KW - milky way

KW - galaxy

U2 - 10.17635/lancaster/thesis/1931

DO - 10.17635/lancaster/thesis/1931

M3 - Master's Thesis

PB - Lancaster University

ER -