Sökning: "circumstellar dust"

Visar resultat 16 - 20 av 25 avhandlingar innehållade orden circumstellar dust.

  1. 16. The death throes of massive stars

    Författare :Sofia Wallström; Chalmers tekniska högskola; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; submillimeter: ISM -- ISM: supernova remnants -- ISM: individual objects: Cassiopeia A -- circumstellar matter -- stars: AGB and post-AGB -- stars: mass-loss -- stars: individual: IRAS 17163-3907 -- quasars: absorption lines -- quasars: individual: B 0218 357 -- galaxies: ISM -- galaxies: abundances -- ISM: molecules;

    Sammanfattning : Massive evolved stars affect their local surroundings as they go through phases of intense mass-loss and eventually explode as supernovae, adding kinetic energy and freshly synthesised material to the interstellar medium. The circumstellar material ejected by the star affects the shape and evolution of the future supernova remnant, and how the material is incorporated into the interstellar medium. LÄS MER

  3. 17. Debris disks and the search for life in the universe

    Författare :Gianni Cataldi; Alexis Brandeker; Jean-Charles Augereau; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; debris disks; astrobiology; Astronomy; astronomi;

    Sammanfattning : Circumstellar debris disks are the extrasolar analogues of the asteroid belt and the Kuiper belt. These disks consist of comets and leftover planetesimals that continuously collide to produce copious amounts of circumstellar dust that can be observed as infrared excess or in resolved imaging. LÄS MER

  4. 18. Companion wind shaping in binaries involving an AGB star

    Författare :Lam Doan; Sofia Ramstedt; Eric Lagadec; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; AGB and post-AGB stars; mass-loss; radio lines; binaries; wind shaping; Astronomy; Astronomi;

    Sammanfattning : Stars of initial masses between 0.8-8 M☉ will become "asymptotic giant branch" (AGB) stars during the final stages of their evolution. During this phase, the stars are characterized by low velocity and high-density winds. LÄS MER

  5. 19. Modelling the Winds from Carbon Rich AGB Stars : Implications for Stellar Evolution and the Chemical Evolution of Galaxies

    Författare :Lars Mattsson; Uppsala universitet; []
    Nyckelord :;

    Sammanfattning : Stars on the AGB are known to lose mass at high rates (10-8 - 10-4 Msun/yr) through slow winds (20 km/s), enriching the inter stellar medium with newly synthesised elements. We explore how the mass loss for C-rich AGB stars depends on the basic stellar parameters by computing a large grid of wind models. LÄS MER

  7. 20. Methanol Masers as Signposts of Star Formation and VLBI Observations of Coronal Emission from Young Stars

    Författare :Michele Pestalozzi; Chalmers tekniska högskola; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY;

    Sammanfattning : Using a consistent survey of the galactic plane at 6.7 GHz as a starting point, this thesis reports on the observational as well as theoretical results achieved by extensively studying of the phenomenon of class II methanol masers. The general catalogue of 6. LÄS MER