Sökning: "circumstellar envelopes"

Visar resultat 1 - 5 av 12 avhandlingar innehållade orden circumstellar envelopes.

  1. 1. A study of circumstellar envelopes : OH/IR stars in the galactic centre and carbon-bearing molecules in the envelopes of oxygen-rich stars

    Författare :Michael Lindqvist; Chalmers tekniska högskola; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; ; red giant stars; molecular spectral lines; kinematics; circumstellar envelopes;

    Sammanfattning : .... LÄS MER

  3. 2. UV Chemistry in the Circumstellar Envelopes of Evolved Stars

    Författare :Maryam Saberi; Chalmers tekniska högskola; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Astrochemistry – molecular processes – stars: abundances – AGB – binaries – circumstellar matter – chromospheres – ultraviolet;

    Sammanfattning : Low- and intermediate-mass stars eject a substantial amount of their material into space during a late phase of stellar evolution, the asymptotic giant branch (AGB) phase. Therefore, they impact the chemistry of the interstellar medium. Due to the intense mass loss, a circumstellar envelope (CSE), rich in gas and dust, forms around the AGB star. LÄS MER

  4. 3. Charting Circumstellar Chemistry of Carbon-rich AGB Stars

    Författare :Ramlal Unnikrishnan Nair; Chalmers tekniska högskola; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; submillimeter: stars; astrochemistry; stars: mass-loss; circumstellar matter; stars: winds; outflows; Stars: AGB and post-AGB;

    Sammanfattning : Stars of low to intermediate initial masses (0.8 - 8 M⊙) enter the asymptotic giant branch (AGB) phase during their late evolution. LÄS MER

  5. 4. Asymptotic Giant Branch stars viewed up-close and far-off : The physics, chemistry, and evolution of their circumstellar envelopes

    Författare :Matthias Maercker; Hans Olofsson; Fredrik L. Schöier; Laurentius B. F. M. Waters; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; AGB stars; evolution; mass-loss; abundances; Astronomy; Astronomi; Astronomy; astronomi;

    Sammanfattning : The asymptotic giant branch (AGB) is the last stage of stellar evolution for stars with masses between 0.8-8 M(sun). This phase is characterised by an intense mass loss, which builds up a circumstellar envelope of dust and gas(CSE). It is through this process that the AGB stars contribute to the chemical evolution of galaxies. LÄS MER

  7. 5. High Resolution Studies of Circumstellar Masers

    Författare :Francisco Colomer Sanmartin; Chalmers tekniska högskola; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY;

    Sammanfattning : This thesis describes in detail the observational procedures that we have followed and developed to analyze several research projects organized at Onsala since 1990 to study the regions of SiO maser emission at 43 GHz in the circumstellar envelopes of late-type stars with very high angular resolution. The compact nature of these SiO maser regions has been demonstrated in this work. LÄS MER