Sökning: "astrofysik"

Visar resultat 1 - 5 av 74 uppsatser innehållade ordet astrofysik.

  1. 1. 'Oumuamua : An analysis of the the debate regarding the first interstellar visitor

    Kandidat-uppsats, Uppsala universitet/Teoretisk astrofysik

    Författare :Erik Westergren; [2022]
    Nyckelord : Oumuamua; asteroid; comet; Avi; Loeb; extraterrestrial; Pan-STARRS; interstellar; alien; vessel; Oumuamua; asteroid; komet; Avi; Loeb; utomjordiskt; PAN-STARRS; interstellär; farkost;

    Sammanfattning : In the year of 2017 in October a strange object with a hyperbolic trajectory was observed in our solar system. There were several hypotheses that scientists used to try to explain what kind of an object it was, but no one could, according to the scientific community as a whole, perpetuate any of these explanations as accepted consensus. LÄS MER

  3. 2. The Metallicity Structure of the Milky Way Halo II : Characterising the distant halo substructure

    Master-uppsats, Uppsala universitet/Observationell astrofysik

    Författare :Amanda Byström; [2022]
    Nyckelord :Milky Way; Galactic archaeology; halo; photometric metallicities; stellar catalogue; Gaia-Enceladus-Sausage; Sagittarius; Pristine survey; metallicity; Gaia mission;

    Sammanfattning : The Milky Way galaxy, like all spiral galaxies, is surrounded by a roughly spherical distribution of stars called the halo. The halo was largely formed when the galaxy merged with smaller galaxies. LÄS MER

  4. 3. The magnetic field of phi Draconis

    Master-uppsats, Uppsala universitet/Observationell astrofysik

    Författare :Nikolaos Papakonstantinou; [2022]
    Nyckelord :stars: atmospheres – stars: chemically peculiar – stars: magnetic field – stars: starspots – stars: individual: phi Dra;

    Sammanfattning : Within this past decade, advances in spectropolarimetric analyses allowed mapping surface characteristics of nearby non-resolved stars with unique characteristics. In this study, we attempt mapping of the magnetic field structure and surface distribution of elements for such a star, the magnetic Ap star phi Dra. LÄS MER

  5. 4. Spatial Variability in the Ionosphere and GNSS Signal Delays in the L-band: A Direct Comparison of In-Situ Satellite- and Swepos-Data

    Kandidat-uppsats, Uppsala universitet/Institutionen för fysik och astronomi; Uppsala universitet/Institutet för rymdfysik, Uppsalaavdelningen

    Författare :Oscar Suneson; [2021]
    Nyckelord :fysik; jonosfären; GNSS; GPS; astrofysik; navigationssystem; mätteknik;

    Sammanfattning : It has been shown that ionospheric irregularities can disturb our GNSS (Global Navigation Satellite System) communication. This disturbance is caused by scintillation of the radio signals when they pass through the ionosphere, leading to lock-on difficulties or in worst case, a loss of position for the GNSS-receiver. LÄS MER

  7. 5. C/O+ charge transfer & the Olson-Demkov model

    Master-uppsats, Uppsala universitet/Teoretisk astrofysik

    Författare :Kristoffer Bengtsson; [2021]
    Nyckelord :Astronomy; Charge transfer; rate coefficient; Carbon; Oxygen; energy defect; spectral modelling; supernovae;

    Sammanfattning : Charge transfer reactions and their rates play a key role in correctly estimating element abundances in astrophysical objects such as supernovae. The reaction $C + O^+ \rightarrow C^+ + O(^1D) + \Delta E$ has been shown to be of significance when estimating oxygen abundances through model spectrum evaluations, and the relative rate of this reaction can under certain circumstances completely dictate the neutralization rate of oxygen ions. LÄS MER