Sökning: "Stars: Late-Type"

Visar resultat 16 - 18 av 18 avhandlingar innehållade orden Stars: Late-Type.

  1. 16. Exploring the Chemical Evolution of Globular Clusters and their Stars : Observational Constraints on Atomic Diffusion and Cluster Pollution in NGC 6752 and M4

    Författare :Pieter Gruyters; Andreas Korn; Piercarlo Bonifacio; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; stars: abundances – stars: atmospheres – stars: fundamental parameters – globular clusters: individual: NGC 6752 and M4 – techniques: spectroscopic; Astronomy with specialization in Astrophysics; Astronomi med intiktning mot astrofysik;

    Sammanfattning : Through the cosmic matter cycle, the chemical evolution of the Milky Way is imprinted in the elemental abundance patterns of late-type stars (spectral types F to K). Due to their long lifetimes ( 1 Hubble time), these stars are of particular importance when it comes to studying the build-up of elements during the early times of our Galaxy. LÄS MER

  3. 17. High Resolution Studies of Circumstellar Masers

    Författare :Francisco Colomer Sanmartin; Chalmers tekniska högskola; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY;

    Sammanfattning : This thesis describes in detail the observational procedures that we have followed and developed to analyze several research projects organized at Onsala since 1990 to study the regions of SiO maser emission at 43 GHz in the circumstellar envelopes of late-type stars with very high angular resolution. The compact nature of these SiO maser regions has been demonstrated in this work. LÄS MER

  4. 18. Infrarödfotometri : instrumentkonstruktion och observationer

    Författare :Björn Wennfors; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Fotometri;

    Sammanfattning : An infrared photometer has been constructed at the Stockholm Observatory, It has an InSb detector cooled by solid nitrogen, and is specially designed to be portable, to be used at existing telescopes, not adapted for IR-work and to be used under non-ideal photometric conditions.The sky chopping, a differential measurement of the star and the background, necessary for infrared observations, Is accomplished by a cooled focal plane chopper with high efficiency,The aperture stop, necessary for suppressing the infrared radiation from the surroundings, is of a new construction which gives high accuracy,The filters, selecting the terrestrial infrared windows are cooled, and mounted in a filter wheel with 15 positions. LÄS MER