Filtyp
Context. The discovery of hot Jupiters, giant gas exoplanets on tight orbits close to their host star, has proven instrumental in the study of exoplanet atmospheres through transit spectroscopy. Just as a temperature increase with height manifests in Earth’s atmosphere due to ozone absorbing ultraviolet radiation, transit spectra of some hot Jupiters has yielded evidence that suggests the presence
Context. With the goal to accurately map about a billion of the Milky Way stars, the astrometric satellite Gaia was launched in December 2013. Its high precision and sensitivity will lead to better understanding of the Galactic structure and evolution. Also, it will be possible to probe the matter distribution in the Galaxy. Aims. To study how well the Galactic matter distribution can be determin
Context. Intensity interferometry was invented and used by R.Hanbury Brown and R.Q.Twiss in the 1960's to measure stellar angular diameters. Its main advantage over conventional interferometry is that it enables very long baselines and is insensitive to poor seeing. However, because it requires very large light collectors, it was never pursued further. The Cherenkov Telescope Array (CTA) is a
In this thesis, I present a case where Dark Matter subhalos would annihilate at some stage in their lifetime. The implication of this scenario could potentially aid the Missing Satellites and the Cusp-Core density profile problem. The Dark Matter particles’ annihilation process and effective “friction” lead to an energy and momentum loss into radiation and hence to the destabilization of the Dark
Context: Data from the recently launched astrometric satellite Gaia will be coming in soon with the final data release expected in 2022. This will provide a very precise map of the Galaxy. The Solar system and Galaxy is thought to be filled with invisible bodies (planetesimals, planets, brown dwarfs, neutron stars, black holes, etc.) and they will affect the observations via gravitational lensing.
The origin of the class of exoplanets typically referred to as hot Jupiters is to this day an unsettled matter. Some of the proposed formation channels predict certain values of the spin-orbit misalignment parameter, i.e. the angle between the stellar rotation axis, and the angular momentum vector of the planet orbit. One such formation channel is tidal capture following Kozai resonance (TCKR). Th
Protoplanetary discs surround young stars for the first few million years after their formation and they are the birthplaces of planetary systems. The thermal structure of the discs is regulated by their dust content and the opacity that it provides. The aim of this project is to investigate the effect grain growth has on the structure of the protoplanetary discs. Hydrodynamical simulations have b
Context. The formation and evolution of the Galactic bulge and the Milky Way is still a debated subject. Observations of, e.g., the X-shaped bulge, cylindrical stellar motions and young stars in the bulge have suggested that the bulge formed through secular evolution of the disk and not through gas dissipation and/or mergers, as thought previously.\\ Data. We use high-resolution optical spectra of
In this thesis we add a temperature dependence to the newly developed variable polytrope equation of state (Varpoly EOS) from Weppner et al. (2015), making it more universal and more applicable for planetary simulations. In this process we develop a new model for the Gruneisen parameter, which is a parameter that describes how pressure changes with the internal energy. This new model conforms to t
For testing three-dimensional (3D) hydrodynamic models of stellar atmospheres, spectroscopy across spatially resolved stellar surfaces with high spectral resolution is desired. 3D models predict center-to-limb changes in asymmetries, shapes, strengths and wavelength positions of spectral line profiles, reflecting the hydrodynamics of the stellar atmosphere. However, except for a few supergiants an
In the thriving field of exoplanet research new discoveries are made all the time, and while most of the observed systems can be explained with classical planet formation models - some are much harder to explain. When stars form they are often surrounded by the remaining material of the nebulae they formed from. Some of this remaining material forms into a protoplanetary disk around the protostars
Researchers in the field of Galactic Archaeology have entered the era of industrial revolution. Upcoming surveys are planning on observing tens of millions of stars and high precision and accuracy must be ensured when deriving their stellar parameters and elemental abundances. Unconventional data-driven techniques hold the promise of efficiently dealing with these vast collections of data while st
Purpose: even in the era of exponential increase in the amount of stellar data gathered, binaries are still often overlooked in observational data due to the special handling they require. The goal of this work is to develop a method capable of automatically and efficiently identifying and extract double-lined spectroscopic binaries (SB2) from a spectroscopic survey, while being scalable and techn
Purpose: In order to study the Galactic Chemical Evolution, elemental abundances are needed. The purpose of this work is to investigate the chemical evolution of the Milky Way by determining several elemental abundances of giants in the local disk. Large surveys are up and coming, and several surveys are already working, and with these, the aim is high quality abundance measurements of several ele
