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| Author(s): |
Stefano Oliveira de Souza
Total Authors: 1
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| Document type: | Doctoral Thesis |
| Press: | São Paulo. |
| Institution: | Universidade de São Paulo (USP). Instituto Astronômico e Geofísico (IAG/SBD) |
| Defense date: | 2024-05-24 |
| Examining board members: |
Beatriz Leonor Silveira Barbuy;
Amancio Cesar Santos Friaca;
Cristina Chiappini Moraes Leite;
Jorge Luis Melendez Moreno;
Basilio Xavier Santiago;
João Francisco Coelho dos Santos Junior
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| Advisor: | Beatriz Leonor Silveira Barbuy; Maria de los Angeles Pérez Villegas |
| Abstract | |
This thesis delves into the multifaceted exploration of Galactic globular clusters (GCs) to unravel their implications for the formation and evolution of the Milky Way bulge and bar. The initial phase of the study involves a meticulous analysis of Palomar 6 (Pal~6) and NGC 6355, located within the inner parts of the Galaxy strongly affected by extinction. We performed the chrono-chemodynamical analysis through a comprehensive approach combining chemical information using FLAMES-UVES and APOGEE spectra, age determination via \\emph photometry, and orbital analysis thanks to \\emph astrometry. Notably, Pal~6 and NGC~6355 were identified as belonging to the in-situ branch of the age-metallicity relation (AMR) of Milky Way GCs. Pal6 was unequivocally confirmed as an in-situ cluster with a determined age of $12.4\\pm1.0$ Gyr and a metallicity of [Fe/H]$ = -1.10\\pm0.09$. Conversely, NGC 6355, with an age of $13.2\\pm0.9$ Gyr and metallicity of [Fe/H]$ = -1.39\\pm0.08$, exhibits characteristics indicative of an ex-situ cluster, manifested through its retrograde motion and distinct chemical composition. The investigation extends to a broader collection of GCs with similar characteristics as Pal~6 and NGC~6355, aiming to unveil their roles in Galactic evolution. Our results highlight the significance of in-situ GCs, characterized by moderately metal-poor compositions (MMP, [Fe/H]$< -1.0$) and ages spanning from $12.0$ to $13.4$ Gyr. Also, their [$\\alpha$/Fe] enhanced values provide insights into the early stages of the bulge. Dynamically, in-situ bulge GCs exhibit prograde motion and low total energy, indicating that they are strongly bound to the Galaxy potential. Furthermore, the research delves into the formation history of early bulge clusters using the AMR of the MMP bulge GCs, tracing their origins back to $13.69\\pm0.12$ Gyr ago. Also, the effective yield obtained is ten times larger than the one fitted to the ex-situ branch, corroborating predictions of the rapid chemical enrichment experienced by the bulge during its early stages. A pivotal aspect of the investigation involves exploring the interplay between GCs and the Galactic bar. By identifying an N-Al-rich star trapped within the bar, we recovered its probable parent cluster as Terzan 5. We estimated that the star was completely captured $315\\pm12$ Myr ago by the bar from Terzan 5 smoothly after several interactions. These findings shed light on the mutual influence of the bar on the evaporation of GCs and the N-Al-rich stars came from GCs that compose the field population of the Galactic bar. This result is particularly interesting because it is the observational evidence for the theoretical model that better explains the evaporation of Terzan 5 to reach its present mass. In essence, this thesis represents a significant advancement in Galactic archaeology, elucidating the pivotal role of GCs in shaping the Galaxy bulge and bar structure and chemical evolution. From deciphering the origins of individual clusters to unravelling wider patterns of Galactic assembly, the research offers a comprehensive understanding of the complex interplay between GCs and the evolving dynamics of our Galaxy. (AU) | |
| FAPESP's process: | 18/22044-3 - Bulge globular clusters: relics of the early formation of the galaxy |
| Grantee: | Stefano Oliveira de Souza |
| Support Opportunities: | Scholarships in Brazil - Doctorate (Direct) |