Found 20 talks width keyword Galactic evolution
The previous years have witnessed a big leap forward in our understanding of the Milky Way. Thanks to the highly accurate astrometry and photometry provided by the Gaia mission in combination with large photometric and spectroscopic all-sky surveys, we have now a clearer view of the chemo-dynamics of the stellar populations that constitute our Galaxy. Our former characterization of the Milky Way components (the bulge, halo, and thick and thin discs) is now compromised by the latest discoveries and their limits are blurrier than ever. However, hints on the kind of events and processes that led to the formation of our Galaxy emerge from the analysis of these high-quality data. In this talk I will review the latest results about what caused the current stellar halo configuration and the observational evidences of the dawn of the Milky Way’s disc. I will also present the project carried out at the ULL/IAC to derive the star formation history of the Milky Way which will provide the temporal information that is still missing in Galactic research.
ID de reunión: 857 3719 8942
Código de acceso: 350472
The first Gigayears of our Galactic halo can be probed by using ancient stellar populations as traced by RR Lyrae stars. Today, with the advancement in our knowledge of RR Lyrae properties belonging to the Halo and to Milky Way satellite systems (Globular clusters and dwarf galaxies) we are able
to provide solid constraints on the link between these stellar systems. Here, we present some recent results concerning the Halo formation by using a detailed evolutionary analysis of RR Lyrae stars for which chemical abundances are available.
Recent years have seen impressive development in cosmological simulations for spiral disc galaxies like the Milky Way. I present a suite of high-resolution magneto-hydrodynamic simulations that include many physical processes relevant for galaxy formation, including star formation, stellar evolution and feedback, active galactic nuclei and magnetic fields. I will discuss how these processes affect the formation of galactic discs, and what these simulations can tell us about the formation of the Milky Way, such as the properties of the Galaxy's putative last significant merger and its effect on the formation of the thick disc and stellar halo.
The lowest metallicity stars that still exist today represent a window into the early Universe. Studying these stars gives us a local avenue to guide our understanding of star formation and supernova feedback in the early Universe, the early build-up of galaxies like our Milky Way, and the epoch of reionization. In this talk I will present recent results of the Pristine survey, a narrow-band photometric survey of the Milky Way designed to get metallicity information for millions of stars very efficiently. I will discuss what we have learned from our analysis of the most metal-poor stars about the early formation of the Milky Way. Moreover, I will highlight the bright future for this type of study in synergy with the upcoming highly-multiplexed spectroscopic surveys.
The field of Galactic archaeology has been very active in recent years, with a major influx of data from the Gaia satellite and large spectroscopic surveys. The major science questions in the field include Galactic structure and dynamics, the accretion history of the Milky Way, chemical tagging, and age-abundance relations. I will give an overview of GALAH as a large spectroscopic survey, and describe how it is complementary to other ongoing and future survey projects. I will also discuss recent science highlights from the GALAH team and compelling questions for future work.
One prediction of ΛCDM is the existence of partially phase-mixed substructures from accreted dwarf galaxies in the Milky Way stellar halo. Substructure originating in a single accretion event can be readily identified as a tight cluster of stars in phase space with similar chemical properties. Recently, the discovery of the Gaia Sausage Enceladus (GSE) has revolutionised our understanding of the complex assembly of the Milky Way halo. We present a review of the chemistry that characterises the last major merger that happened to the Milky Way some 9-10 Gy ago.
At present, our understanding of the formation history of the MW is limited due to the complexity of observing the imprints of accretion events and of reproducing them in numerical simulations. Moreover, though being the only galaxy, in which the Galactic potential can be probed in detail, the distribution of mass in the MW, and hence of the dark matter, is poorly constraint, especially at large distances. In addition, the MW is not isolated, and it has recently been suggested that the infall of the LMC can induce a perturbation in the stellar and dark matter distribution of the MW. As a consequence, the details of the formation history of our Galaxy are still unknown, such as the number of accretion events, the mass of the accreted galaxies, and the epoch of these events. Yet this information is crucial to understand our environment and to constrain the theoretical models and simulations that try to reproduce it.
One of the major challenges of the field is that a tremendous number of multi-aspect (astrometric, photometric and spectroscopic) observations at significant depth is required to study the morphology, the kinematics and the chemistry of the outskirts of our Galaxy, where are located the signatures of these events. Hopefully, the advent of recent and incoming complementary large surveys, such as the European Gaia mission, UNIONS (Ultraviolet Near Infrared Optical Northern Survey), Pristine, Pan-STARRS (PS), WEAVE or LSST (Legacy Survey of Space and Time), is offering a new global point of view on our Galaxy’s halo, allowing us to precisely probe the Galactic potential our the MW, and to retrace itsaccretion history.
In this talk I will present recent works that have been conducted to better catarerized our Galaxy and its history with some of the existing surveys mentioned above. In addition, I will present the major improvement that will bring this new generation of large, multi-aspect surveys, to study both our Galactic history, as well as the fundamental nature of the dark matter.
Reconstructing the past of the Milky Way depends on the study of its metal-poor stars, which either have been formed in the Galaxy itself in the first billion years, or have been accreted through mergers of satellite galaxies over time. These stars are usually found in what is known as the Milky Way halo, a light — in terms of total mass — stellar component which is usually made of stars whose kinematics significantly deviates from that of the Galactic disc.
In this talk, I will discuss how it has been possible to use the astrometric and spectroscopic data delivered by Gaia and complementary surveys to shed light on the past of our Galaxy, through the study of its halo. Besides the discovery of the possible last significant merger experienced by the Milky Way, the use of 6D phase space information and chemical abundances allowed to reconstruct the impact this merger had on the early Milky Way disc, and the time it occurred, as well as to discover that some of the most metal-poor stars in the Galaxy possibly formed in a disc. This last finding would imply that the dissipative collapse that led to the formation of the old Galactic disc must have been extremely fast.
Wide hot subdwarf B (sdB) binaries with main-sequence companions are outcomes of stable mass transfer from evolved red giants. The orbits of these binaries show a strong correlation between their orbital periods and mass ratios. The origins of this correlation have, so far, been lacking a conclusive explanation.
We have performed a small but statistically significant binary population synthesis study with the binary stellar evolution code MESA. We have used a standard model for binary mass loss and a standard Galactic metallicity history. We have achieved an excellent match to the observed period - mass ratio correlation without explicitly fine-tuning any parameters. Furthermore, our models produce a good match to the observed period - metallicity correlation.
We demonstrate, for the first time, how the metallicity history of the Milky Way is imprinted in the properties of the observed post-mass transfer binaries. We show that Galactic chemical evolution is an important factor in binary population studies of interacting systems containing at least one evolved low-mass (Mi < 1.6 Msol) component. Finally, we provide an observationally supported model of mass transfer from low-mass red giants onto main-sequence stars.
Zoom link: https://rediris.zoom.us/j/98017007654
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- TBDThursday December 14, 2023 - 10:30 GMT (Aula)
- GESCOPThursday January 18, 2024 - 10:30 GMT (Aula)