2004/09/29 by F. Svensson, Svensson, F., H. -G. Ludwig +1
Physics and Astronomy · #Astrophysics (astro-ph) #FOS: Physical sciences #astro-ph
paper · pdf · doi:10.48550/arxiv.astro-ph/0409714
Proc. 13th Cool Stars Workshop, Hamburg, 5-9 July 2004, F.Favata et al., eds., 5 pages, 8 figures
arxiv created 2004/09/29 · arxiv updated 2009/12/01
We used a series of COBOLD 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 ca. 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.