Sökning: "stellar evolution"

Visar resultat 26 - 30 av 77 avhandlingar innehållade orden stellar evolution.

  1. 26. Molecules at stellar death: from the winds of massive evolved stars to supernova remnants

    Författare :Sofia Wallström; Chalmers tekniska högskola; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; stellar mass-loss; supernova remnants; circumstellar matter; IRAS 17163-3907; yellow hypergiant stars; Cassiopeia A;

    Sammanfattning : Massive stars play a key role in the chemical and dust budget of the galaxy, producing heavy elements, molecules, and dust. At the end of their lives they evolve through stages of significant mass-loss which affect the subsequent evolution of the star, including whether or not it will eventually explode as a supernova (SN). LÄS MER

  3. 27. Young Stellar Clumps and Clusters in the Local Universe

    Författare :Matteo Messa; Göran Östlin; Angela Adamo; Petri Väisänen; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Astronomy; astronomi;

    Sammanfattning : The thesis introduces the process of star formation at the scale of galaxies, where a turbulent--dominated interstellar medium (ISM) can locally collapse under self-gravity. This collapse results in a star formation process which is hierarchical both in space and time. LÄS MER

  4. 28. Exploring the Chemical Evolution of Globular Clusters and their Stars : Observational Constraints on Atomic Diffusion and Cluster Pollution in NGC 6752 and M4

    Författare :Pieter Gruyters; Andreas Korn; Piercarlo Bonifacio; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; stars: abundances – stars: atmospheres – stars: fundamental parameters – globular clusters: individual: NGC 6752 and M4 – techniques: spectroscopic; Astronomy with specialization in Astrophysics; Astronomi med intiktning mot astrofysik;

    Sammanfattning : Through the cosmic matter cycle, the chemical evolution of the Milky Way is imprinted in the elemental abundance patterns of late-type stars (spectral types F to K). Due to their long lifetimes ( 1 Hubble time), these stars are of particular importance when it comes to studying the build-up of elements during the early times of our Galaxy. LÄS MER

  5. 29. Magnetic fields and chemical maps of Ap stars from four Stokes parameter observations

    Författare :Naum Rusomarov; Oleg Kochukhov; Nikolai Piskunov; Werner Weiss; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; chemically peculiar stars; magnetic fields; spectropolarimetry; Doppler imaging; stellar atmospheres; Astronomy with specialization in Astrophysics; Astronomi med intiktning mot astrofysik; Astronomy; Astronomi;

    Sammanfattning : Our knowledge of stellar magnetic fields relies almost entirely on circular polarization observations, which has historically limited our understanding of the stellar magnetic field topologies. Recently, it has become possible to obtain phase-resolved high-resolution spectropolarimetric observations in all four Stokes parameters for early-type magnetic stars. LÄS MER

  7. 30. The nature of stars with a common origin: clues from metallicity, elemental abundances, and kinematics

    Författare :Cheng Liu; Astronomi - Genomgår omorganisation; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Stars: abundances; Galaxy: evolution; Galaxy: solar neighbourhood; Galaxy: bulge; Galaxy: globular clusters;

    Sammanfattning : Most of field stars originate from dissolved star clusters. If the gas cloud is well mixed the stars in the cluster are expected to be chemically homogenous. LÄS MER