title: Unveiling the Milky Way’s History Using Young & Old Population Variable Stars
creator: Medina Toledo, Gustavo Enrique
subject: ddc-520
subject: 520 Astronomy and allied sciences
subject: ddc-530
subject: 530 Physics
description: This dissertation focuses on classical Cepheids and RR Lyrae stars as tracers of the recent star formation and the early assembly of the Milky Way, respectively.    I use data from the Gaia spacecraft to search for classical Cepheids in Galactic open clusters. I confirm (reject) several Cepheid-cluster associations considered in previous studies as bona-fide and identify new potential cluster Cepheid candidates. I also study the feasibility of using young cluster ages as tests of the Cepheid period-age relation, and conclude that their usage still faces difficulties due to their sparsely populated red giant branches, their stochastically sampled main-sequence turn-offs, and their quick dissolution.    I combine publicly available and proprietary data to study outer halo RR Lyrae stars, in the context of the Halo Outskirts with Variable Stars (HOWVAST) survey. Using Dark Energy Camera data, I search for distant halo RR Lyrae stars and detect ∼ 500 candidates, ∼ 25% of which are not reported in the literature, and 11 of which are new discoveries beyond 100 kpc. I use their pulsation properties and radial distribution to investigate the role that the accretion of satellites play in the formation and shape of the halo. Finally, I derive atmospheric parameters, chemical abundances, and kinematics for a sample of distant halo RR Lyrae stars using Magellan Inamori Kyocera Echelle spectra. I speculate about their origin, looking for hints of their association with satellites and stellar streams, and conclude that the accretion of sub-haloes contributes significantly to building up the outer halo.    The results of this thesis confirm the pivotal role of variable stars as tools to unveil the Milky Way’s evolution.
date: 2022
type: Dissertation
type: info:eu-repo/semantics/doctoralThesis
type: NonPeerReviewed
format: application/pdf
identifier: https://archiv.ub.uni-heidelberg.de/volltextserverhttps://archiv.ub.uni-heidelberg.de/volltextserver/32368/1/PhD_Thesis_GustavoMedinaToledo_submitted.pdf
identifier: DOI:10.11588/heidok.00032368
identifier: urn:nbn:de:bsz:16-heidok-323684
identifier:   Medina Toledo, Gustavo Enrique  (2022) Unveiling the Milky Way’s History Using Young & Old Population Variable Stars.  [Dissertation]     
relation: https://archiv.ub.uni-heidelberg.de/volltextserver/32368/
rights: info:eu-repo/semantics/openAccess
rights: http://archiv.ub.uni-heidelberg.de/volltextserver/help/license_urhg.html
language: eng