3D model atmospheres and their impact in stellar evolution
Master/PhD
Detailed hydrodynamical simulations of stellar atmospheres have recently become available. This sophisticated set of models includes all relevant physical processes that govern the evolution of convective outer layers and are of key importance to accurately predict stellar properties. This projects aims at coupling the average results of these simulations to 1D hydrostatic evolutionary codes and study its impact in physical and pulsation properties of stars.
Supervisor: Víctor Aguirre Børsen-Koch
Anchoring the asteroseismic age scale
Bachelor/Master
Asteroseismology is a powerful tool to determine precise stellar properties, including masses of red giant stars. This project aims at anchoring the zero-point of the asteroseismic age scale by comparing mass determinations (and thus ages) of solar-like oscillators in clusters with those predicted by isochrone fitting to the CMD.
Supervisor: Víctor Aguirre Børsen-Koch
Constraining overshoot in intermediate mass stars
Master/PhD
An adequate prescription of mixing processes in stellar interiors is of crucial importance for precise predictions of stellar ages across the HRD. This projects will constrain the amount of non-canonical mixing from convective cores in stars from ~1.1-2.5 solar masses using frequency combinations in the main-sequence phase and gravity modes period spacing in the base of the red giant branch.
Supervisor: Víctor Aguirre Børsen-Koch
Developing 3D magnetohydrodynamic models of stellar atmospheres
Bachelor/Master
A grid of 3D stellar atmosphere models, mainly covering the cooler side of the HR diagram, has provided important insight about stellar convection. Particularly, it has contributed to the accurate determination of stellar properties, the characterisation of stellar spectra, exoplanets, and Galactic chemical evolution.
These 3D simulations include a realistic treatment of the physical processes that take place in the outer layers of the stars, avoiding magnetic fields. Therefore, this project aims at generating key 3D stellar atmospheres models, incorporating the treatment of both magneto- and hydrodynamics.
Supervisor: Luisa Fernanda Rodriguez Diaz
Dissecting the Milky Way disc with SAGA and Kepler/K2
Master/PhD
Combining Strömgren photometry with Kepler asteroseismic observations provides a powerful tool to determine self-consistent properties of thousands of stars. This project couples the SAGA observations with data from Kepler to study gradients and variations in the population of the Milky Way disc as a function of position and distance, revealing the main dynamical processes that formed the thin and thick discs.
Supervisor: Víctor Aguirre Børsen-Koch
Exploring the effects of metallicity in 3D stellar atmosphere models
Bachelor/Master
A huge diversity of stars are found in the universe. They have different temperatures, sizes, colours, and chemical compositions, which means that the physical processes that take place inside the stars can vary significantly. The goal of this project is to compare and analyse 3D stellar models with fixed temperatures, surface gravities, but different metallicities.
Supervisor: Luisa Fernanda Rodriguez Diaz
Exploring the Initial Mass Function (IMF) with asteroseismology
Master/PhD
The IMF is an empirical function that describes the distribution of initial masses for a population of stars. So far its determination and test of its universality has been hampered by the difficulty in estimating stellar masses for a field stars across the Galaxy. In this project the student will use stellar masses derived from seismology to explore whether new constraints can be derived for the IMF.
Supervisor: Víctor Aguirre Børsen-Koch
Galactic archaeology with APOGEE and Kepler/K2
Master/PhD
Combining spectroscopy and asteroseismology to determine accurate stellar properties can provide stringent constraints into the formation and evolution of the Milky Way. This project uses the latest observations from the APOGEE survey and Kepler asteroseismic data of red giants to study correlations between age, composition, and velocity dispersions as a tracer of our Galactic history.
Supervisor: Víctor Aguirre Børsen-Koch
Mass loss along the red giant branch
Bachelor/Master
The efficiency of mass loss in stars is still very much unconstrained. In this project, the student will combine asteroseismic and classical stellar parameters to fit the spectral energy distribution of red giant stars and match observed multi-band photometry. The goal is to determine whether stars display any infrared excess, which could be the signature of mass-loss. The study of this excess will give insights on the mass-loss mechanism.
Supervisor: Víctor Aguirre Børsen-Koch
One size fits all: determining stellar properties of solar-like oscillators
Bachelor/Master
The manner in which properties of stars are determined from asteroseismology depends on the availability and quality of the data, as well as the evolutionary stage where the star is. The aim of this project is to refine and optimize the BAyesian STellar Algorithm (BASTA) for determining accurate stellar properties of solar-like oscillators across all evolutionary stages, as well as update its library of stellar isochrones and pulsation frequencies.
Supervisor: Víctor Aguirre Børsen-Koch
