Sökning: "cool stars"

Visar resultat 1 - 5 av 9 avhandlingar innehållade orden cool stars.

  1. 1. Magnetic fields of cool active stars

    Författare :Lisa Rosén; Oleg Kochukhov; Eric Stempels; Andrew Collier Cameron; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; stars: magnetic field; stars: late-type; stars: activity; stars: imaging; polarisation; starspots; Astronomy; Astronomi;

    Sammanfattning : Magnetic fields are present throughout the universe and are very important for many astrophysical processes. Magnetic field influences a star throughout its life and affects nearby objects such as planets. LÄS MER

  2. 2. 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. 3. Magnetic fields of cool stars from near-infrared spectropolarimetry

    Författare :Alexis Lavail; Oleg Kochukhov; Nikolai Piskunov; Gaitee Hussain; Jeff Valenti; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; stars: magnetic field; stars: pre-main-sequence; stars: late-type; techniques: spectroscopic; techniques: polarimetric; Astronomy; Astronomi;

    Sammanfattning : Magnetic fields rule many physical processes in and around stars throughout their lifetime. All cool stars possess a magnetic field, likely generated by dynamo processes. In order to properly understand the evolution of cool stars, we need to understand their magnetism. LÄS MER

  4. 4. Spectral Analysis of Neutron Capture Elements in the Laboratory and Stars

    Författare :Martin Lundqvist; Astronomi - Genomgår omorganisation; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; cosmic chemistry; Astronomy; space research; Atom- och molekylärfysik; Atomic and molecular physics; Astronomi; Sm; Hf; Os; Ir; Neutron capture processes; rymdvetenskap; kosmisk kemi; cool stars; Spectroscopy; atomic data;

    Sammanfattning : The pedigree of the elements heavier than iron is a vital question in the history and evolution of our galaxy. The elements up to and including those of the iron group are produced mainly through fusion processes within stars, giving the stars their energy. LÄS MER

  5. 5. Dynamical atmospheres and winds of M-type AGB stars

    Författare :Sara Bladh; Susanne Höfner; Kjell Eriksson; Patricia Whitelock; Uppsala universitet; []
    Nyckelord :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;

    Sammanfattning : 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. LÄS MER