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arXiv · 0712.0387

Signatures of Granulation in the Spectra of K-Dwarfs

I. Ramirez·C. Allende Prieto·D. L. Lambert·M. Asplund
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Abstract

Very high resolution (R>150,000) spectra of a small sample of nearby K-dwarfs have been acquired to measure the line asymmetries and central wavelength shifts caused by convective motions present in stellar photospheres. This phenomenon of granulation is modeled by 3D hydrodynamical simulations but they need to be confronted with accurate observations to test their realism before they are used in stellar abundance studies. We find that the line profiles computed with a 3D model agree reasonably well with the observations. The line bisectors and central wavelength shifts on K-dwarf spectra have a maximum amplitude of only about 200 m/s and we have been able to resolve these granulation effects with a very careful observing strategy. By computing a number of iron lines with 1D and 3D models (assuming local thermodynamic equilibrium), we find that the impact of 3D-LTE effects on classical iron abundance determinations is negligible.

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I. Ramirez, C. Allende Prieto, D. L. Lambert, M. Asplund. 2007-12-03. Signatures of Granulation in the Spectra of K-Dwarfs. https://arxiv.org/abs/0712.0387

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