Search for dissertations about: "Stars"

Showing result 16 - 20 of 262 swedish dissertations containing the word Stars.

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

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

    Abstract : 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. READ MORE

  4. 17. On the Winds of Carbon Stars and the Origin of Carbon : A Theoretical Study

    Author : Lars Mattsson; Susanne Höfner; Nils Bergvall; Kjell Olofsson; Martin Groenewegen; Uppsala universitet; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; AGB stars; carbon stars; mass loss; stellar winds; circumstellar matter; cosmic dust; stellar evolution; nucleosynthesis; galactic chemical evolution; Astronomy and astrophysics; Astronomi och astrofysik; Astronomy; Astronomi; Fysik; Physics;

    Abstract : Carbon is the basis for life, as we know it, but its origin is still largely unclear. Carbon-rich Asymptotic Giant Branch (AGB) stars (carbon stars) play an important rôle in the cosmic matter cycle and may contribute most of the carbon in the Galaxy. READ MORE

  5. 18. Investigations of Heavy Elements in Am and HgMn stars

    Author : Linus Dolk; Atomfysik; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; HgMn stars; spectroscopy; heavy elements; Astronomi; Astronomy; Chemically peculiar stars; Am star; Fysicumarkivet A:2002:Dolk;

    Abstract : The relationship between the HgMn and Am classes of chemically peculiar stars has been investigated primarily by observing abundances of heavy elements, including Pr, Nd, Hg, Tl and Bi. The main objective of the investigation has been to gather observational evidence to provide a better understanding of the mechanisms producing the abundance anomalies of these stars, and to establish the relationship between the two classes. READ MORE

  6. 19. Dynamical atmospheres and winds of M-type AGB stars

    Author : Sara Bladh; Susanne Höfner; Kjell Eriksson; Patricia Whitelock; Uppsala universitet; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; Late-type stars; AGB stars; stellar winds; atmospheres; mass-loss; outflows; circumstellar matter; dust; hydroynamics; radiative transfer; Astronomy with specialization in Astrophysics; Astronomi med intiktning mot astrofysik;

    Abstract : Mass loss, in the form of slow stellar winds, is a decisive factor for the evolution of cool luminous giants, eventually turning them into white dwarfs. These dense outflows are also a key factor in the enrichment of the interstellar medium with newly produced elements from the interior of these stars. READ MORE

  7. 20. Gravitational lensing as a probe of the first stars and galaxies

    Author : Claes-Erik Rydberg; Erik Zackrisson; Lise Christensen; Stockholms universitet; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; stars: Population III; first stars; Galaxies: high-redshift; Galaxies: Population III; dark ages; reionization; techniques: photometric; Astronomy; astronomi;

    Abstract : This thesis investigates the potential for detection and identification of primordial stars, galaxies, and supernovae at high redshift.Simulations indicate that the first Population III stars should appear in minihalos of mass M = 105-106 Msol at z ≈ 10-30. READ MORE