Sökning: "AXEL BRANDENBURG"

Visar resultat 1 - 5 av 13 avhandlingar innehållade orden AXEL BRANDENBURG.

  1. 1. Origin of solar surface activity and sunspots

    Författare :SARAH JABBARI; AXEL BRANDENBURG; Vasilis Archontis; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Sun-Solar activity-Sunspots; teoretisk astrofysik; Theoretical Astrophysics;

    Sammanfattning : In the last few years, there has been significant progress in the development of a new model for explaining magnetic flux concentrations, by invoking the negative effective magnetic pressure instability (NEMPI) in a highly stratified turbulent plasma. According to this model, the suppression of the turbulent pressure by a large-scale magnetic field leads to a negative contribution of turbulence to the effective magnetic pressure (the sum of non-turbulent and turbulent contributions). LÄS MER

  3. 2. Magnetic helicity in astrophysical dynamos

    Författare :Simon Candelaresi; Axel Brandenburg; Renzo Ricca; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Astronomy; astronomi;

    Sammanfattning : The broad variety of ways in which magnetic helicity affects astrophysical systems, in particular dynamos, is discussed.The so-called alpha effect is responsible for the growth of large-scale magnetic fields. The conservation of magnetic helicity, however, quenches the alpha effect, in particular for high magnetic Reynolds numbers. LÄS MER

  4. 3. From irrotational flows to turbulent dynamos

    Författare :Fabio Del Sordo; Axel Brandenburg; Mordecai-Mark Mac Low; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; astrophysics; magnetic fields; insterstellar medium; MHD; dynamo; turbulence; instability; Astronomy; astronomi;

    Sammanfattning : Many of the celestial bodies we know are found to be magnetized:the Earth, many of the planets so far discovered, the Sun and other stars,the interstellar space, the Milky Way and other galaxies.The reason for that is still to be fully understood, and this work is meant to be a step in that direction. LÄS MER

  5. 4. Generation of magnetic fields on galactic scale

    Författare :Fabio Del Sordo; Axel Brandenburg; Oliver Gressel; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Magnetic fields; galaxies; Astronomy; astronomi;

    Sammanfattning : In these pages we will go through the topic of astrophysical magnetic fields, focusing on galactic fields, their observation and the theories that have been developed for a proper understanding of the these physical phenomena.We review the main work in the study of galactic magnetic fields, often seeing how it is important to deal with problems of general validity in order to be able to point out the right elements needed for a correct interpretation of specific situations. LÄS MER

  7. 5. Gravitational waves from primordial magnetic sources

    Författare :Yutong He; Axel Brandenburg; David Weir; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES;

    Sammanfattning : This licentiate thesis gives an overview of modified gravity and primordial magnetic fields,bridged by gravitational waves (GWs) as a phenomenological probe of both sectors.First we derive the GW equation in a homogeneous and isotropic background from general relativity. LÄS MER