Sökresultat

This bachelor thesis concerns the NIR spectral region of the Sr-filament, a substructure of the fan located in the equatorial skirt of Eta Carinae. The primary objective was to identify emission features intrinsic to the Sr-filament, and to tabulate these in a line-list spanning the spectral range λλ990 − 2410 nm. A secondary objective was concerned with the use of identified parity-forbidden atom

In this project spectra of neutral calcium between 2000-30000 cm-1 have been recorded by the Fourier Transform Spectrometer Bruker HR IRFTS at Lund Observatory. Using 204 spectral lines, 78 energy levels in the calcium atom have been derived. Level mixing and self absorption of some transitions are discussed. The energy levels in the previously not resolved triplet 4s5g 3G have been measured in th

When inspecting the currently known pulsar population one finds a velocity distribution which is in constrast to the galactic rotation curve. This has lead researchers to believe that the pulsars receive linear momentum (a kick) at the SN event which produces these. In this work we try and see what can be learned about these kicks by studying the existing double neutron star binary population. We

The usual terrestrial optical astronomy is focused on observing vertically through the atmosphere. When traveling through the atmosphere, the light coming from distant objects gets distorted by the turbulent atmosphere due to varying refractive indices. The effects varies with time and causes position shifts, size changes and intensity variations in an image. The closer to the ground that the ligh

A 3m ground-based optical telescope, with active and adaptive optics, is a powerful and versatile research tool. This type of telescopes is affordable and manageable also for communities with limited previous telescope experience. While there are many scientific and technical reports regarding modern 3m class telescopes, there is no document giving a comprehensive description. This paper is an att

Gravitational light deflection in the Solar System can be detected by high precision astrometric measurements. We discuss the parametrized post-Newtonian framework and the comparison of metric theories of gravity. At the precision of a few micro-arcseconds, Gaia data will permit tests of the PPN parameters beta and gamma and to distinguish monopole and quadrupole gravitational light deflection. Ac

Gravitational light deflection in the Solar System can be detected by high precision astrometric measurements. We discuss the parametrized post-Newtonian framework and the comparison of metric theories of gravity. At the precision of a few micro-arcseconds, Gaia data will permit tests of the PPN parameters beta and gamma and to distinguish monopole and quadrupole gravitational light deflection. Ac

Stars form in clusters or groups. In these crowded environments, they are likely to experience encounters with one another. These encounters may perturb their planetary systems and cause the ejection of one or more planets. N-body simulations were performed to study the effect of encounters between stars on their planetary systems in young stellar clusters. Two categories of young clusters were mo

Scattered in our galaxy today are planets that have no host star and are only bound to the galaxy. These so called free floating planets are believed to be formed around stars but have later been ejected by passing stars perturbing their orbits, or have undergone close interactions with another planet in a planetary system. This results in one of the planets becoming tightly bound in an often ecce

Thirteen stellar objects known as extended globular clusters were found in the Halo of the Andromeda Galaxy. Three of these extended clusters have quantitative properties which are subsequently used to determine whether clusters of extended size could survive in the orbits of the Milky Way Galaxy. The question of whether extended clusters could survive in the orbits of the Milky Way, is interestin

Recent work by Nissen and Schuster have found two distinct populations of halo stars with -1<5 alpha [Fe/H] -0<5. Both populations are kinematically selected to be halo stars. The differences between the two groups are the alpha -elemental abundances and the [Na/Fe] and [Ni/Fe] ratios. From angular momentum space, we can see that the majority of these stars do not show any extreme kinematic indica

Blue stragglers were first discovered as hotter and more luminous than the turnoff in the globular cluster M3. Their presence is typically explained by the interplay between stellar collisions and mass transfer in binary systems. In this thesis, I study blue stragglers produced from primordial binary evolution. This is done by both reproducing individual blue stragglers, to examine the different f

The first detailed chemical abundance analysis of the M-dwarf (M4.0) exoplanet-hosting star Ross 128 is presented here, based upon near-infrared (1.5-1.7 μm), high-resolution (R ∼ 22,500) spectra from the SDSS Apache Point Galactic Evolution Experiment survey. We determined precise atmospheric parameters T eff = 3231 ±100 K, log g = 4.96 ±0.11 dex and chemical abundances of eight elements (C, O, M

Investigating the chemical homogeneity of stars born from the same molecular cloud at virtually the same time is very important for our understanding of the chemical enrichment of the interstellar medium and with it the chemical evolution of the Galaxy. One major cause of inhomogeneities in the abundances of open clusters is stellar evolution of the cluster members. In this work, we investigate va

At least 25 percent of white dwarfs show atmospheric pollution by metals, sometimes accompanied by detectable circumstellar dust/gas discs or (in the case of WD 1145+017) transiting disintegrating asteroids. Delivery of planetesimals to the white dwarf by orbiting planets is a leading candidate to explain these phenomena. Here, we study systems of planets and planetesimals undergoing planet–planet

Context. We present the second Gaia data release, Gaia DR2, consisting of astrometry, photometry, radial velocities, and information on astrophysical parameters and variability, for sources brighter than magnitude 21. In addition epoch astrometry and photometry are provided for a modest sample of minor planets in the solar system. Aims. A summary of the contents of Gaia DR2 is presented, accompani

Context. Detailed chemical abundances of Galactic stars are needed in order to improve our knowledge of the formation and evolution of our galaxy, the Milky Way. Aims. We took advantage of the GIANO archive spectra to select a sample of Galactic disc stars in order to derive their chemical inventory and to compare the abundances we derived from these infrared spectra to the chemical pattern derive