Sökning: "stellar astrophysics"

Visar resultat 1 - 5 av 139 avhandlingar innehållade orden stellar astrophysics.

  1. 1. Stellar Winds of Cool Giants : Investigating the Mass-Loss Mechanism of AGB Stars

    Författare :Sofie Liljegren; Susanne Höfner; Kjell Eriksson; Bernd Freytag; Hans Olofsson; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; late-type stars; AGB stars; stellar winds; stellar atmospheres; dust; stellar pulsation; hydrodynamics; radiative transfer;

    Sammanfattning : Asymptotic giant branch (AGB) stars are luminous cool giants of low to intermediate mass that are strongly pulsating and non-spherical, with heavy mass loss through a stellar wind. The mass loss makes these stars important for galactic chemistry, as the wind enriches the interstellar medium with new elements and dust, and it determines the final fate of these stars. LÄS MER

  3. 2. Advances in Stellar Astrophysics from Laboratory Spectroscopy

    Författare :Stefan Ivarsson; Atomfysik; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Astronomy; iridium; osmium; uranium; oscillator strengths; Spectroscopy; term analysis; line profiles; line structure; astrophysics; Sun; Chi Lupi; 17 Comae A; chemically peculiar; praseodymium; stars; space research; cosmic chemistry; Astronomi; rymdvetenskap; kosmisk kemi; Fysicumarkivet A:2004:Ivarsson;

    Sammanfattning : Investigation of astrophysical plasmas, such as stellar atmospheres, require both knowledge of atomic structure and data. We present laboratory instruments, techniques and tools for acquisition of the data required to derive important atomic parameters such as, wavelengths, oscillator strengths and line profiles. LÄS MER

  4. 3. On the Abundances of Li, Be and O in Metal-Poor Stars in the Galaxy

    Författare :Ana Elia García Pérez; Martin Asplund; Bengt Gustafsson; Francesca Primas; Beatriz Barbuy; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Astronomy; galactic evolution; stellar abundances; stellar atmospheres; spectral line formation; stellar mixing; Astronomi; Astronomy and astrophysics; Astronomi och astrofysik;

    Sammanfattning : Stellar atmospheres constitute excellent environments to study the chemical evolution of our Galaxy. The chemical composition of these atmospheres reflects the composition of the gas from where these stars were born. LÄS MER

  5. 4. Stellar kinematics in surveys and simulations

    Författare :Daniel Mikkola; Astronomi - Genomgår omorganisation; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Galactic dynamics; stellar dynamics; simulations; Gaia; Galactic dynamics; Stellar kinematics; Numerical simulations; Statistical methods; Solar neighborhood;

    Sammanfattning : We study stellar motions in the Milky Way with N-body simulations and large astrometric samples from ESA's Gaia mission. We identify two kinematic populations for white dwarfs in the Solar neighbourhood. We also investigate the accreted halo and reveal two new structures. LÄS MER

  7. 5. Characterising Young Stellar Binaries

    Författare :Per Calissendorff; Markus Janson; Eric Stempels; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Binaries; stellar ages; multiplicity; Astronomy; astronomi;

    Sammanfattning : Stars are dispersed all over the sky within our Galaxy, appearing in large varieties of ages and sizes. How- ever, estimating said traits proves not to always be trivial, but certain circumstances allow us to probe the characteristics of stellar binaries. LÄS MER