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Hydrodynamical simulations of convection-related stellar micro-variability

Författare

  • Fredrik Svensson
  • Hans-Günter Ludwig

Summary, in English

We used a series of CO<sup>5</sup>BOLD hydrodynamical model atmospheres covering stellar objects from white dwarfs to red giants to derive theoretical estimates of the photometric and photocentric stellar variability in wavelength-integrated light across the Hertzsprung-Russell diagram. We validated our models against solar measurements from the SoHO/VIRGO instrument. Within our set of models we find a systematic increase of the photometric as well as photocentric variability - which turn out to be closely connected - with decreasing surface gravity. The estimated absolute levels of the photocentric variability do not affect astrometric observations on a precision level expected to be achieved by the GAIA mission - with the exception of close-by giants. The case of supergiants remains to be investigated. In view of the ongoing debate about the photometric non-detection of p-modes in Procyon by the Canadian MOST satellite we remark that we obtain a factor of approximately equals 3 in amplitude between the granular background "noise" in the Sun and Procyon. This statement refers to a particular representation of temporal power spectra as discussed in Sect. 5.

Avdelning/ar

Publiceringsår

2005

Språk

Engelska

Sidor

979-984

Publikation/Tidskrift/Serie

European Space Agency, (Special Publication) ESA SP

Volym

560

Dokumenttyp

Konferensbidrag

Förlag

European Space Agency

Ämne

  • Astronomy, Astrophysics and Cosmology

Nyckelord

  • Exoplanets
  • Granulations
  • Variability
  • Astrometry

Conference name

13th Cambridge Workshop on Cool Stars, Stellar Systems and the Sun

Conference date

2004-07-05 - 2004-07-09

Conference place

Hamburg, Germany

Status

Published

ISBN/ISSN/Övrigt

  • ISSN: 1609-042X
  • ISSN: 0379-6566
  • CODEN: ESPUD4