A hunt for C-19 members: the most metal-poor structure in the Galaxy

Vos, Heidi de (2023) A hunt for C-19 members: the most metal-poor structure in the Galaxy. Bachelor's Thesis, Astronomy.

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Abstract

This thesis searched for stars belonging to the current most metal-poor structure in the Galaxy: stellar stream C-19. With a mean metallicity of [Fe/H] = -3.38±0.06 it breaks through the globular cluster metallicity floor and has the opportunity to fill this mysterious observational gap. However, by showing signs of a globular cluster past with its low metallicity dispersion while simultaneously containing the dynamical hotness of a dwarf galaxy, C-19’s progenitor remains undefined. Through the selection of stars in 4D and 5D dynamics for several parts of C-19’s integrated orbit, new candidate members are gathered. These stars hint at a much wider metallicity and velocity dispersion currently visible in the C-19 members. However, follow-up research is necessary. This thesis offers 86 new stars selected based on 5 dynamical dimensions: a location (α, δ) within 5◦ of the orbit, a proper motion (μα, μδ) inside 1◦ of the obit, and a radial velocity between vr,orbit±50km/s. This includes 4 new Blue Horizontal Branch star and 1 variable Asymptotic Giant Branch star, which provide the opportunity for an improved distance calculation by employing standard candles now fitting with C-19 in 5 dimension instead of 4. In addition, the 4D selection found 78 stars containing a metallicity of [Fe/H] < -2.5 (including 36 stars with [Fe/H] < -3), several of which correspond exceptionally well in both coordinate- and proper motion space, which are in need of a radial velocity measurement.

Item Type:	Thesis (Bachelor's Thesis)
Supervisor name:	Starkenburg, E.
Degree programme:	Astronomy
Thesis type:	Bachelor's Thesis
Language:	English
Date Deposited:	22 Nov 2023 08:36
Last Modified:	22 Nov 2023 08:36
URI:	https://fse.studenttheses.ub.rug.nl/id/eprint/31667

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