Search for dissertations about: "dwarfs"

Showing result 1 - 5 of 25 swedish dissertations containing the word dwarfs.

  2. 1. The faintest stars : A study of white, red and brown dwarfs

    Author : Leif Festin; Uppsala universitet; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; Astronomy; brown dwarfs; white dwarfs; M dwarf; low luminosity; luminosity function; mass function; Pleiades; Astronomi; Astronomy and astrophysics; Astronomi och astrofysik; astronomi; Astronomy;

    Abstract : The local space density of the faintest stars, including M dwarfs, white dwarfs and brown dwarfs has been studied by two different methods.By using dark nebulae as opaque outer screens, the luminosity functions of M dwarfs and white dwarfs were studied as volume-limited and dynamically unbiassed foreground samples. READ MORE

  4. 2. Inside Pulsating White Dwarfs: Clues from time-resolved spectroscopy

    Author : Rubina Kotak; Astronomi - Genomgår omorganisation; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; pulsating white dwarfs; convection; asteroseismology; Astronomi; Astronomy; spectroscopy; Fysicumarkivet A:2002:Kotak;

    Abstract : Several analyses using time-resolved optical spectrocopy of pulsating white dwarfs are presented. The data have been put to a number of uses. First, line-of-sight velocities associated with the pulsations have been measured in three hydrogen-atmosphere white dwarfs (DAVs), bringing the total number of such measurements up to five. READ MORE

  5. 3. Characterising Emblematic Binaries at the Lowest Stellar and Substellar Masses

    Author : Per Calissendorff; Markus Janson; Koraljka Mužić; Stockholms universitet; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; astrometry; binaries; brown dwarfs; low-mass stars; multiplicity; substellar; Astronomy; astronomi;

    Abstract : Stars are involved in most research fields of astronomy, ranging from studies of faraway galaxies, exploding supernovae, to more nearby exoplanets and even our own Sun. As such, it is paramount that our physical interpretation of stars is accurate. READ MORE

  6. 4. Studies of Double and Multiple Stars Using Space Astrometry

    Author : Carl Fredrik Quist; Astronomi - Genomgår omorganisation; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; cosmic chemistry; space research; brown dwarfs; Binaries; astrometric binaries; astrometry; Hipparcos; GAIA; Astronomy; data analysis; Astronomi; rymdvetenskap; kosmisk kemi; Fysicumarkivet A:2000:Quist;

    Abstract : This thesis introduces and summarizes four papers dealing with the study of double and multiple stars using space astrometry. The introduction gives a brief review of the role of binary observations in various fields of astronomy --- star formation, stellar masses and the mass-luminosity relation, initial mass function, detection of sub-stellar mass companions. READ MORE

  7. 5. Metallicity determination of M dwarfs

    Author : Sara Lindgren; Ulrike Heiter; Ansgar Reiners; Uppsala universitet; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; stars: low mass - stars: abundances; fundamental parameters - technique: spectroscopic; photometric - planets and satellites: formation;

    Abstract : M dwarfs constitute around 70% of all stars in the local Galaxy. Their multitude together with their long main-sequence lifetimes make them important for studies of global properties of the Galaxy such as the initial mass function or the structure and kinematics of stellar populations. READ MORE