Signatures of Convection in the Spectrum of Procyon: Fundamental Parameters and Iron Abundance

By C. Allende Prieto, Martin Asplund, R. G. López, D. Lambert. 2001

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We have observed the spectrum of Procyon A (F5 IV) from 4559 to 5780 Å with a signal-to-noise ratio of ~103 and a resolving power of 2 × 105. We have measured the line bisectors and relative line shifts of a large number of Fe I and Fe II lines, comparing them to those found in the solar spectrum. A three-dimensional hydrodynamical model atmosphere has been computed and is tested against observations. The model reproduces in detail most of the features observed, although we identify some room for improvement. At all levels, the comparison of the three-dimensional time-dependent calculations with the observed spectral lines shows a much better agreement than for classical homogeneous models, making it possible to refine previous estimates of the iron abundance, the projected rotational velocity, the limb darkening, and the systemic velocity of the Procyon binary system. The difference between the iron abundance determined with the three-dimensional model and its one-dimensional counterpart is ≲0.05 dex. We find consistency between the iron abundance derived from Fe I and Fe II lines, suggesting that departures from LTE in the formation of the studied lines are relatively small. The scatter in the iron abundance determined from different lines still exceeds the expectations from the uncertainties in the atomic data, pointing out that one or more components in the modeling can be refined further.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/8c3011389ba18ef8e5960d9bc643a21458d5003f

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Citations in the corpus

Three-dimensional hydrodynamical simulations of surface convection in red giant stars: impact on spectral line formation and abundance analysis (2007, methodology): “…same procedure adopted in other recent investigations of the effects of surface convection and granulation on solar and stellar spectroscopy (Asplund et al. 1999, 2000a,b, 2005; Asplund 2000; Asplund & Garcı́a Pérez 2001; Allende Prieto et al. 2001, 2002b; Nissen et al. 2002; Collet et al. 2006).”
The chemical compositions of Galactic disc F and G dwarfs (2002, methodology): “The empirical Holweger-Müller model, as revised by Grevesse & Sauval (1999), and the MISS (Allende Prieto et al. 2001a) empirical model, also return iron abundances that are independent of the lower excitation potential.”
Line formation in solar granulation IV. (O I), O I and OH lines and the photospheric O abundance (2003, methodology): “It is therefore clearly of importance to extend the work by Allende Prieto et al. (2001) to include also the O I and OH lines analysed with the same 3D hydrodynamical model atmosphere.”
S4N: A spectroscopic survey of stars in the solar neighborhood: The nearest 15 pc (2004, methodology): “While the forbidden line has been shown to be nearly immune to departures from LTE, it is weak and blended with a Ni I line (Allende Prieto et al. 2001; Asplund et al. 2004).”
Theoretical isochrones in several photometric systems I. Johnson-Cousins-Glass, HST/WFPC2, HST/NICMOS, Washington, and ESO Imaging Survey filter sets (2002, background): “The consequences of spatial and thermal inhomogeneities in the atmosphere of the Sun and Procyon have been investigated by Allende Prieto et al. (2001, 2002).”
Oxygen abundances in nearby stars - Clues to the formation and evolution of the Galactic disk (2007, methodology): “5, this value reduces to AO = 8.72, in good agreement with most recent determinations of the solar oxygen abundance (e.g., Allende Prieto et al. 2001; Asplund et al. 2004, 2005; Meléndez 2004; Shchukina et al. 2005).”