Sökning: "brown dwarfs"
Visar resultat 1 - 5 av 6 avhandlingar innehållade orden brown dwarfs.
1. The faintest stars : A study of white, red and brown dwarfs
Sammanfattning : 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. LÄS MER
2. Characterising Emblematic Binaries at the Lowest Stellar and Substellar Masses
Sammanfattning : 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. LÄS MER
3. Studies of Double and Multiple Stars Using Space Astrometry
Sammanfattning : 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. LÄS MER
4. High-contrast imaging of low-mass companions and debris disks
Sammanfattning : The search for exoplanets, i.e., planets orbiting other stars than the Sun, is a relatively new research field, but has already established itself as one of the most prolific and intriguing areas of astronomy. LÄS MER
5. Globulettes : a new class of very small and dense interstellar clouds
Sammanfattning : The space between stars is not empty, but filled with a thin gas and microscopic dust grains, together forming the so-called interstellar medium. Matter is concentrated into clouds of very different sizes, ranging from giant molecular cloud complexes to massive isolated dark small isolated cloudlets, called globules. LÄS MER