Sökning: "stars: activity"

Visar resultat 1 - 5 av 14 avhandlingar innehållade orden stars: activity.

  1. 1. Magnetic fields of cool active stars

    Författare :Lisa Rosén; Oleg Kochukhov; Eric Stempels; Andrew Collier Cameron; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; stars: magnetic field; stars: late-type; stars: activity; stars: imaging; polarisation; starspots; Astronomy; Astronomi;

    Sammanfattning : Magnetic fields are present throughout the universe and are very important for many astrophysical processes. Magnetic field influences a star throughout its life and affects nearby objects such as planets. LÄS MER

  3. 2. Probing the effect of UV radiation on the chemistry in circumstellar envelopes around evolved stars

    Författare :Maryam Saberi; Chalmers tekniska högskola; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Stars: abundances - Stars: AGB – Stars: individual: R Scl – Stars: binaries – Stars: carbon – Stars: circumstellar matter – Stars: chromospheres – Ultraviolet: stars;

    Sammanfattning : Low to intermediate mass (0.8 - 8 M⊙) stars lose a substantial amount of their mass in the last phase of stellar evolution, the asymptotic giant branch (AGB) phase. Hence, they are one of the main suppliers of dust and gas in the interstellar medium and important for the enrichment of galaxies. LÄS MER

  4. 3. UV Chemistry in the Circumstellar Envelopes of Evolved Stars

    Författare :Maryam Saberi; Chalmers tekniska högskola; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Astrochemistry – molecular processes – stars: abundances – AGB – binaries – circumstellar matter – chromospheres – ultraviolet;

    Sammanfattning : Low- and intermediate-mass stars eject a substantial amount of their material into space during a late phase of stellar evolution, the asymptotic giant branch (AGB) phase. Therefore, they impact the chemistry of the interstellar medium. Due to the intense mass loss, a circumstellar envelope (CSE), rich in gas and dust, forms around the AGB star. LÄS MER

  5. 4. Methanol Masers as Signposts of Star Formation and VLBI Observations of Coronal Emission from Young Stars

    Författare :Michele Pestalozzi; Chalmers tekniska högskola; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY;

    Sammanfattning : Using a consistent survey of the galactic plane at 6.7 GHz as a starting point, this thesis reports on the observational as well as theoretical results achieved by extensively studying of the phenomenon of class II methanol masers. The general catalogue of 6. LÄS MER

  7. 5. Gene expression and regeneration in ophiuroids: A study of transcriptional activity and regeneration in the temperate Amphiura filiformis and Antarctic Ophionotus victoriae

    Författare :Gavin Burns; Göteborgs universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; echinoderm; regeneration; ophiuroid; gene expression; antarctica;

    Sammanfattning : Regeneration, in which lost or damaged tissues are re-grown, is a common phenomenon amongst animals and especially so within the ophiuroids (brittle stars) of the phylum echinodermata. The process of regeneration begins with the injury event followed by a period of cell and tissue reorganization which results in wound healing and tissue re-growth. LÄS MER