Filtyp
This is a bachelor thesis bent on introducing the field of exoplanet research. It primarily includes descriptions of the various detection methods, with some detail into how the methods yield parameter estimates by means of least-squares algorithms. The feasibility of combining state-of-the-art astrometric capabilities of Gaia and radial velocity measurements from ground level is briefly discussed
Imaging of stellar surfaces in visible wavelengths is one of the current frontiers in astronomy. With a few exceptions, stars can not be seen in visible light as anything but point objects with current technology. Being able to properly image stars would open up the door to a vast field of new discoveries, permitting direct studies of phenomena such as rotationally deformed stars, circumstellar di
In this report we present the testing and development made using the Lund Observatory Vacuum Echelle Spectrograph (LOVES) during the last few years. Hardware development includes an assembly from base components due to relocation and necessary calibrations of the optics. Software devel- opment includes the making of a basic image processing pipeline for the instrument. The testing of LOVES wavelen
The current Lambda Cold Dark Matter cosmology predicts galaxy growth by hierarchical merging, leading to galaxy substructure like tidal streams and dark matter subhalos devoid of stars. The goal of this thesis is to investigate whether tidal stream-subhalo interactions can leave observable gaps in the streams, and at which rate this might happen in a galaxy like the Milky Way. The stream-subhalo i
Metal-poor (MP) stars in the Milky Way (the Galaxy) and its satellite galaxies open a window into the earliest times in the history of the Universe, probing the chemistry of the earliest times. Recent galaxy formation simulations predict that the oldest MP stars are those on tightly bound orbits in the inner regions of a galaxy (Tumlinson 2010). Applying this to the Milky Way, MP stars in the bulg
Nucleosynthesis is the mechanism which produces new elements in nuclear reactions. Nuclear reaction rates are highly temperature dependant, and nuclear reactions take place in very hot environments. Current theories predict that the light elements such as hydrogen and helium were produced during the Big Bang. On the other hand, the core of stars produce heavier elements through nuclear fusion. The
Stellar abundances are important for understanding the chemical evolution of galaxies and provide us with constraints on stellar evolution and supernova nucleosynthesis. To determine stellar abundances accurately, atomic data is crucial. This data is incomplete for many elements, especially in the infrared region. In particular, hyperfine structure (hfs) data in the near-infrared region is lacking
Context: The formation of the Galactic Bulge is a topic of active research. There are many scenarios based on observations and Galactic evolution models. The key properties which need to be well constrained observationally are the metallicity distributions of stars and the spatial metallicity gradients. The metallicity distribution of stars in the inner Galactic Bulge (|b|<4o) is a subject of ongo
Over the past two decades many discoveries of exoplanets have been made, which have drawn much attention to extrasolar planetary systems. In this work we study the composition of these systems and search for analogues of the Solar System. We considered the planets in the database at exoplanet.eu. The search of solar-like systems required these planets to be classified. The classification was perf
A major avenue in the study of the Galaxy is the investigation of stellar populations and Galactic chemical evolution by stellar spectroscopy. Due to the dust obscuration in the line-of-sight, stars in the plane and toward the centre of the Galaxy can only be observed in the near-IR wavelength region. Important questions can thus be addressed by observing stars in the near-IR, a field that is in r
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
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
