Sökning: "main sequence stars"

Visar resultat 11 - 15 av 17 avhandlingar innehållade orden main sequence stars.

  1. 11. Water in molecular outflows and shocks: Studies with Odin and Herschel

    Författare :Per Bjerkeli; Chalmers tekniska högskola; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Herbig-Haro objects – ISM:individual objects: HH 54; outflows; VLA 1623 – ISM:jets and outflows – ISM:molecules – ISM:abundances – ISM:supernova remnants – stars:formation – stars:pre-main-sequence – stars:winds;

    Sammanfattning : This thesis describes observations and analyses of water in molecular outflows from young stellar objects. The abundance of this molecule (with respect to molecular hy- drogen) is deduced from observations carried out with primarily the Odin and Herschel telescopes. LÄS MER

  3. 12. G och K stjärnors effektiva temperaturer och deras kol-, kväve- och syrehalter

    Författare :Urban Olof Frisk; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES;

    Sammanfattning : This study is aimed at increasing our knowledge and understanding of the evolutionary stages during and after the main sequence phase. The study is based on new photometric and spectroscopic observations of stars in the region from the main sequence and up to the red giants. LÄS MER

  4. 13. Circumstellar Debris Disks : Observational Studies of Cold Dust and Gas Emission in Planetary Nurseries

    Författare :Ricky Nilsson; Alexis Brandeker; Mark Wyatt; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; circumstellar disks; debris disks; Kuiper belts; planet formation; submillimeter imaging; photometry; coronagraphy; integral-field spectroscopy; Astronomy; astronomi;

    Sammanfattning : Planetary systems form in disks of gas and dust surrounding newborn stars. The young circumstellar environment is characterized by frequent collisions between rocky bodies, leading to a continuous production of small dust grains. LÄS MER

  5. 14. Debris disks from an astronomical and an astrobiological viewpoint

    Författare :Gianni Cataldi; Alexis Brandeker; Göran Olofsson; Eric Stempels; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; debris disks; planetary systems; exoplanets; astrobiology; circumstellar matter; biomarker; biosignature; extraterrestrial life; Astronomy; astronomi;

    Sammanfattning : In this licentiate thesis, I consider debris disks from an observational, astronomical viewpoint, but also discuss a potential astrobiological application. Debris disks are essentially disks of dust and rocks around main-sequence stars, analogue to the Kuiper- or the asteroid belt in our solar system. LÄS MER

  7. 15. PTF12os and iPTF13bvn : Two stripped-envelope supernovae discovered by the Palomar Transient Factory

    Författare :Christoffer Fremling; Jesper Sollerman; Ross Church; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; sovernovae;

    Sammanfattning : This thesis is based on research made by the intermediate Palomar Transient Factory [(i)PTF], and it is particularly closely tied to the still ongoing research on the stripped-envelope (SE) supernova (SN), iPTF13bvn (Type Ib), that occurred in the nearby galaxy NGC 5806. This SN was initially thought to have been the explosion of a very massive Wolf-Rayet (WR) star, but I have shown that this is very likely not the case. LÄS MER