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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
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
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
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
Context. Large scale chemical abundance gradients in the Galactic disks, small-scale abundance structures, and the mean chemical abundance values in the Solar vicinity, are important constraints to Galactic chemo-dynamical formation and evolution models. The formation and evolution of stars, and interstellar gas and dust depends on the distribution and evolution of matter in the Galaxy. Therefore,
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
Context. Effective temperature is one of the fundamental stellar parameters. A traditional spectroscopic way to determine it is from optical spectra using excitation balance of Fe-lines. With technological advances and the advent of the next generation telescopes there will be an emphasis on the relatively unexplored near-IR (NIR) wavelength region (1-5 μm). A method to determine the effective tem
In this project I have studied the effect of gas expulsion on the evolution of stellar clusters. What effect the rate of gas removal and the quantity of gas removed has on the evolution on the cluster will be studied through computer simulations with the NBody6 code and compared to analytical predictions. The rate at which gas is removed has a very significant impact on how the cluster evolves
Where the dust in a protoplanetary disk is as the disk evolves over time is essential to know for further studies of the planet formation process. A new star is created alongside a stellar nebula. The nebula contains rock, ice and gas which are not accreted to the star. Our nebula is constructed using the Minimum Mass Solar Nebula model and the column density is studied as the protoplanetary disk
This is an analysis of all the planets at exoplanets.org, with the goal of finding out how many of these that could possibly have moons supporting life. I have first calculated the ranges of the habitable zones (HZ:s) for the stars in the archive, using the Runaway Greenhouse model for the inner limit, and the Maximum Greenhouse model for the outer limit, as presented by Kopparapu et al. (2013A).
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
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
