Sökning: "Atmospheres"

Visar resultat 1 - 5 av 128 avhandlingar innehållade ordet Atmospheres.

1. 1. 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

3. 2. Atmospheric Species and Spectral Radiation in Terrestrial Exoplanets : Implications for Astrobiology

   Författare :Samuel Konatham; Javier Martin-Torres; María-Paz Zorzano Mier; Akos Kereszturi; Luleå tekniska universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Exoplanets; Atmospheres; Habitability; Human vision; Scotopic vision; Photopic vision; Spectral radaition; Atmosfärsvetenskap; Atmospheric science;

   Sammanfattning : The physical properties of the planets and their parent stars are fundamental in the composition of atmospheres and radiative environments, which fundamentally determine their surface temperature and habitability. The atmospheric composition and radiation play a vital role in the emergence of life. LÄS MER

4. 3. Atomic Processes in Stellar Atmospheres : Inelastic Collisions and Effects on Late-type Spectra

   Författare :Yeisson Fabian Martinez Osorio; Paul Barklem; Karin Lind; Nikolai Piskunov; Carlos Allende Prieto; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; Spectral line: formation; atomic data; stellar abundances.; Fysik med inriktning mot astrofysik; Physics with specialization in Astrophysics;

   Sammanfattning : Chemical abundances as measured from stellar spectral lines are often subject to uncertainties due to lack of accurate data for inelastic collisions, which is needed for non-local thermodynamic equilibrium (non-LTE) modelling. For cool stars, understanding of collision processes with electrons and hydrogen atoms is required to achieve high precision measurements. LÄS MER

5. 4. Theories for convection in stellar atmospheres

   Författare :Åke Nordlund; Stockholms universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES;

   Sammanfattning : .... LÄS MER

7. 5. Magnetic and Chemical Structures in Stellar Atmospheres

   Författare :Oleg Kochukhov; Nikolai Piskunov; Georges Michaud; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Astronomy; chemically peculiar stars; high-resolution spectroscopy; magnetic fields; Doppler imaging; rapidly oscillating Ap stars; Astronomi; Astronomy and astrophysics; Astronomi och astrofysik; Astronomy; Astronomi;

   Sammanfattning : We present an investigation of the magnetic field geometries and inhomogeneous distribution of chemical elements in the atmospheres of peculiar A and B stars. Our study combines high-quality spectroscopic and spectropolarimetric stellar observations with the development and application of novel techniques for theoretical interpretation of the shapes and variability of stellar line profiles. LÄS MER