Sökning: "radio astronomy"

Visar resultat 1 - 5 av 117 avhandlingar innehållade orden radio astronomy.

  1. 1. Radio emission from supernovae

    Författare :Esha Kundu; Peter Lundqvist; Claes Fransson; Stephen Reynolds; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; supernovae; radio emission; hydrodynamical simulation; Astronomy; astronomi;

    Sammanfattning : This thesis presents the modeling of radio and X-ray emissions from supernova (SN) shock fronts and hydrodynamical simulations of SN-circumstellar medium (CSM) interaction. The interaction of SN ejecta with the CSM drives a strong shock wave into the CSM. LÄS MER

  3. 2. Gas Production in Distant Comets

    Författare :Marcus Gunnarsson; F Peter Schloerb; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Astronomy; Comets; Radio Astronomy; Molecular Spectroscopy; Coma Models; Astronomi; Astronomy and astrophysics; Astronomi och astrofysik; astronomi; Astronomy;

    Sammanfattning : Molecular spectroscopy at radio wavelengths is a tool well suited for studying the composition and outgassing kinematics of cometary comae. This is particularly true for distant comets, i.e. comets at heliocentric distances greater than a few AU, where the excitation of molecules is inefficient other than for rotational energy levels. LÄS MER

  4. 3. Radio waves in the ionosphere : Propagation, generation and detection

    Författare :Tobia Carozzi; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Astronomy; Astronomi; Astronomy and astrophysics; Astronomi och astrofysik; Space Physics; rymdfysik;

    Sammanfattning : We discuss various topics concerning the propagation, generation, and detec-tionof high-frequency (HF) radio waves in the Earth's ionosphere. With re-gardsto propagation, we derive a full wave Hamiltonian and a polarization evo-lutionequation for electromagnetic waves in a cold, stratified magnetoplasma. LÄS MER

  5. 4. Modeling of Radio Emission from Supernovae : Application to Type Ia

    Författare :Esha Kundu; Peter Lundqvist; Claes Fransson; Talvikki Hovatta; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Supernova; Circumstellar interaction; Radio emission; Astronomy; astronomi;

    Sammanfattning : The interaction of supernova (SN) ejecta with the circumstellar medium (CSM) drives a strong shock wave into the CSM. These shocks are ideal places where effective particle acceleration and magnetic field amplification can take place. LÄS MER

  7. 5. Mm-wave Radio Astronomy Instrumentation for the Onsala Space Observatory and SEST

    Författare :Nicholas D. Whyborn; Chalmers tekniska högskola; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; mm-wave receiver; phase retrieval holography; focal plane imaging array; radio astronomy instrumentation; SIS mixer;

    Sammanfattning : The thesis presents work done in developing instrumentation for mm- and submm-wave radio astronomy. The work described is in several fields. The greater part of the thesis is concerned with sensitive heterodyne receivers and in particular the cryogenically cooled mixers. In paper A the SEST telescope and its observing system are described. LÄS MER