Line formation in solar granulation I. Fe line shapes, shifts and asymmetries

By Martin Asplund, Åke Nordlund, R. Trampedach, C. Allende Prieto, Robert F. Stein. 2000

332 citations recorded by the source corpus.

Realistic ab-initio 3D, radiative-hydrodynamical convection simulations of the solar granulation have been ap- plied to Fei and Feii line formation. In contrast to classical analyses based on hydrostatic 1D model atmospheres the pro- cedure contains no adjustable free parameters but the treatment of the numerical viscosity in the construction of the 3D, time- dependent, inhomogeneous model atmosphere and the elemen- tal abundance in the 3D spectral synthesis. However, the nu- merical viscosity is introduced purely for numerical stability purposes and is determined from standard hydrodynamical test cases with no adjustments allowed to improve the agreement with the observational constraints from the solar granulation. The non-thermal line broadening is mainly provided by the Doppler shifts arising from the convective flows in the solar photosphere and the solar oscillations. The almost perfect agree- ment between the predicted temporally and spatially averaged line profiles for weak Fe lines with the observed profiles and the absence of trends in derived abundances with line strengths, seem to imply that the micro- and macroturbulence concepts are obsolete in these 3D analyses. Furthermore, the theoretical line asymmetries and shifts show a very satisfactory agreement with observations with an accuracy of typically 50-100 ms 1 on an absolute velocity scale. The remaining minor discrep- ancies point to how the convection simulations can be refined further.

View Paper: https://www.semanticscholar.org/paper/4c1b0554f270a70528364eba7bc5779af018faca

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

1. I. Ramírez
2. Martin Asplund
3. C. Allende Prieto
4. U. Heiter
5. J. Laming
6. S. Basu
7. N. Grevesse
8. Pat Scott

Citations in the corpus

• The elemental composition of the Sun: II. The iron group elements Sc to Ni (2014, background): “In an earlier series of papers (Asplund et al. 2000a; Asplund et al. 2000b; Asplund 2000; Allende Prieto et al. 2001b, Allende Prieto et al. 2002, Asplund et al. 2004; Asplund 2004; Asplund et al. 2005b; Scott et al. 2006; Asplund et al. 2005a, hereafter AGS05; Meléndez & Asplund 2008, Scott et…”
• Scaled solar tracks and isochrones in a large region of the Z-Y plane I. From the ZAMS to the TP-A (2008, background): “The recent update of the solar chemical composition (Asplund et al 2005, 2006 and Montalban et al. 2006) has led to a decrease in the CNO and Ne abundances of the order of 30%.”
• The solar magnetic field (2006, background): “lly carried out [395, 396]. These simulations are fully compressible and take into account non-gray radiative transfer and a realistic equation of state. They reproduce a wide variety of observations [397, 398]. Similarly realistic 3-D MHD simulations of magnetoThe solar magnetic eld 49 Figure 22. S”
• NLTE abundances of Mn in a sample of metal-poor stars ⋆ (2008, background): “Most of the NLTE investigations refer to the lighter elements, such as C, N, O (Asplund et al. 2005a,b; Takeda & Honda 2005) or Na, Mg, and Al (Gehren et al. 2006), but some also deal with heavier elements, among them Mashonkina et al. (2007: Ca), Korn et al. (2003: Fe), Bruls (1993: Ni),…”
• Helioseismology and Solar Abundances (2007, methodology): “Allende Prieto et al. (2002) examined the solar carbon abundance using the [C I] line at 872.7 nm, again using the 3D simulation of Asplund et al. (2000b), and did a calculation similar to what Allende Prieto et al. (2001) did for the [O I] line at 630 nm.”
• The chemical composition of the Sun (2009, methodology): “The revised abundance is slightly higher than in Asplund et al. (2004): log ǫO = 8.69 ± 0.05.”
• Giants in the Local Region (2007, background): “The increase in the scatter is due to two basic factors: (1) blends increase in the giants as the temperature drops below 4600 K, and (2) the solar data are affected by blends, and the proportions are similar in the Sun and other stars (both dwarfs and giants) down to about 4600 K.”
• HE 1327–2326, an Unevolved Star with [Fe/H] < –5.0. I. A Comprehensive Abundance Analysis (2005, methodology): “Significant three-dimensional effects on CH and NH lines are expected (Asplund 2004; Asplund et al. 2005a).”
• The Solar Chemical Composition (2004, methodology): “…in stellar abundance analyses (e.g. Nordlund & Dravins 1990; Dravins & Nordlund 1990; Steffen et al. 1995; Atroshchenko & Gadun 1994; Stein & Nordlund 1998; Asplund et al. 1999, 2000a,b, 2004a,b; Asplund 2000, 2004; Asplund & Garćıa Pérez 2001; Steffen & Holweger 2002; Vögler et al. 2004).”
• The Distribution of the Elements in the Galactic Disk (2006, methodology): “Themost interesting feature of the surface map is the localized high-abundance region at l 120 at about 3Y4 kpc from the Sun.”