SwePub
Sök i SwePub databas

  Utökad sökning

Träfflista för sökning "L773:158381163X "

Sökning: L773:158381163X

  • Resultat 1-2 av 2
Sortera/gruppera träfflistan
   
NumreringReferensOmslagsbildHitta
1.
  • Ludwig, Hans-Günter, et al. (författare)
  • 3D Hydrodynamical Modelling of the Solar Chromosphere
  • 2003
  • Ingår i: International Astronomical Union Symposium. - 158381163X ; 219, s. 40-40
  • Konferensbidrag (refereegranskat)abstract
    • We report on 3D radiation-hydrodynamics modelling of the non-magneticsolar atmosphere with emphasis on the problem of the acoustic heating ofthe chromosphere. Our models include the generation of acoustic waves inthe uppermost layers of the solar convection zone their propagationthrough the photospheric layers and their ultimate transformation intoshock fronts which are dissipated in the chromospheric layers. In thechromosphere we find a bimodal temperature distribution consisting of acool non-shocked and hot shocked gas component. The hot gas is locatedin small-scale filamentary structures associated with propagating shockfronts which evolve rapidly in time. The detailed spatial and temporalinformation provided by the models can be exploited to predictobservational diagnostics hitherto unavailable. We present syntheticimages of features in the millimetre and sub-millimetre radio continuumpotentially observable by the Atacama Large Millimetre Array (ALMA).
  •  
2.
  • Tautvaisiene, Grazina, et al. (författare)
  • Stellar abundance anomalies: open cluster NGC 7789
  • 2004
  • Ingår i: Stars as Suns: Activity, Evolution and Planets. - 158381163X ; , s. 985-989
  • Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
    • High-resolution spectra of six giants and three core-helium-burning "clump" stars in the open cluster NGC 7789 have been obtained on the Nordic Optical Telescope to investigate abundances of up to 19 chemical elements and to compare the elemental abundances in differently evolved stars. The overall metallicity of the cluster stars was found to be close to solar ([Fe/H]=-0.04 +- 0.05). Compared with the Sun, mean abundances in the investigated giants and clump stars suggest that carbon is underabundant by approximately the same value of 0.2 dex, the 12C/13C ratios lie in the range from 11 to 7. However, the nitrogen overabundance is larger in the clump stars. The mean C/N ratios are lowered to the values of 1.3 +- 0.2 in the clump stars and to the values of 1.9 +- 0.5 in the giants. Among other chemical elements an overabundance of sodium is noticeable and for some other alpha-elements may be suspected. Abundances of heavy chemical elements in all nine stars were found to be close to solar.
  •  
Skapa referenser, mejla, bekava och länka
  • Resultat 1-2 av 2

Kungliga biblioteket hanterar dina personuppgifter i enlighet med EU:s dataskyddsförordning (2018), GDPR. Läs mer om hur det funkar här.
Så här hanterar KB dina uppgifter vid användning av denna tjänst.

 
pil uppåt Stäng

Kopiera och spara länken för att återkomma till aktuell vy