NLTE formation of the silicon spectrum: silicon abundance in three-dimensional model of the solar atmosphere
Heading:
| 1Shchukina, NG, 1Sukhorukov, AV 1Main Astronomical Observatory of the National Academy of Sciences of Ukraine, Kyiv, Ukraine |
| Kinemat. fiz. nebesnyh tel (Online) 2013, 29(1):26-49 |
| Start Page: Solar Physics |
| Language: Russian |
Abstract: We investigated the NLTE formation of the silicon spectrum in a three-dimensional (3D) hydrodynamical snapshot of the solar atmosphere using realistic atomic model. It is shown that the joint action of line source function deficits and line opacity excesses caused by the overpopulation of the lower levels of Si I lines produces more pronounced effects on line central depths and equivalent widths in intergranular regions than in granular ones. We fitted the silicon abundances AW and AD from the equivalent widths W and central depths D of 65 Si I lines using the 3D snapshot. The total silicon abundance error caused by the neglect of NLTE and 3D effects and by uncertainties in the van der Waals broadening constant 6 is shown to be –0.1 dex. Employing the semi-classical theory of Anstee, Barklem and O’Mara to calculate g6, we get good agreement between AW and AD values. The average difference AW –AD does not exceed 0.01 dex both for NLTE and LTE. The abundances AW appear to be in disagreement with AD values when Unsld’s approximation for the calculation of γ6 is applied. We analysed the “solar” oscillator strength scale of Gurtovenko and Kostik and experimental oscillator strength scales of Garz and Becker et al. The “solar” oscillator strengths lggfW are shown to minimize the trends with line strength in the derived individual abundances AW and AD as well as their differences AW – AD and standard deviations. Using the 3D snapshot, “solar” oscillator strengths and ABO theory, we obtained that silicon NLTE-abundance equals 7.549±0.016. This value is in good agreement with the CI chondrite meteoritic abundance recommended by Grevesse and Sauval. |
| Keywords: atmosphere, NLTE-formation, Sun |
References:
1.C. W. Allen, Astrophysical Quantities, (London, The Athlone, 1973).
2.E. A. Gurtovenko and R. I. Kostyk, Fraunhofer Spectrum and a Solar Force System for Oscillators (Nauk. Dumka, Kiev, 1989) [in Russian].
3.A. V. Sukhorukov and N. G. Shchukina, “Solar Spectrum of Silicon and Diagnostics of the Solar Atmosphere”, Kinemat. Phys. Celest. Bodies 28, 27–34 (2012).
https://doi.org/10.3103/S0884591312010084
4.A. V. Sukhorukov and N. G. Shchukina, “NLTE Formation of the Solar Silicon Spectrum: Silicon Abundance in One-Dimensional Models of The Solar Atmosphere,” Kinemat. Phys. Celest. Bodies 28, 169–182 (2012).
https://doi.org/10.3103/S0884591312040071
5.N. G. Shchukina and A. V. Sukhorukov, “Solar” Oscillator Strength Scale and Determination of the LTE Silicon Abundance,” Kinemat. Phys. Celest. Bodies 28, 3–21 (2012).
https://doi.org/10.3103/S0884591312020055
6.E. Anders and N. Grevesse, “Abundances of the Elements-Meteoritic and Solar,” Geochim. Cosmochim. Acta 53, 197–214 (1989).
https://doi.org/10.1016/0016-7037(89)90286-X
7.M. Asplund, “Line Formation in Solar Granulation. III. The Photosperic Si and Meteoritic Fe Abundances,” Astron. Astrophys. 359, 755–758 (2000).
8.M. Asplund, “New Light on Stellar Abundance Analyses: Departures from LTE and Homogeneity,” Annu. Rev. Astron. Astrophys. 43(1), 481–530 (2005).
https://doi.org/10.1146/annurev.astro.42.053102.134001
9.M. Asplund, N. Grevesse, and A. J. Sauval, “The Solar Chemical Compositon,” in Cosmic Abundances as Records of Stellar Evolution and Nucleosynthesis, Ed. by F. N. Bash and T. G. Barnes (ASP, San Francisco, 2005), Vol. 336, pp. 25–38.
10.M. Asplund, N. Grevesse, A. J. Sauval, and P. Scott, “The Chemical Composition of the Sun,” Annu. Rev. Astron. Astrophys. 47(1), 481–522 (2009).
https://doi.org/10.1146/annurev.astro.46.060407.145222
11.M. Asplund, H.-G. Ludwig, Å. Hordlund, and R. F. Stein, “The Effects of Numerical Resolution on Hydrodynamical Surface Convection Simulations,” Astron. Astrophys. 359, 669–681 (2000).
12.M. Asplund, Å. Nordlund, R. Trampedach, et al., “Line Formation in Solar Granulation. I. Fe Line Shapes, Shifts and Asymmetries,” Astron. Astrophys. 359, 729–742 (2000).
13.L. Auer, P. Fabiani Bendicho, and J. Trujillo Bueno, “Multidimensional Radiative Transfer with Multilevel Atoms. I. ALI Method with Preconditioning of the Rate Equations,” Astron. Astrophys. 292, 599–615 (1994).
14.J. N. Bahcall, S. Basu, M. Pinsonneault, and A. M. Serenelli, “Helioseismological Implications of Recent Solar Abundance Determinations,” Astrophys. J. 618(2), 1049–1056 (2005).
https://doi.org/10.1086/426070
15.P. S. Barklem and B. J. O’Mara, “The Broadening of p-d and d-p Transitions by Collisions with Neutral Hydrogen Atoms,” Mon. Notic. Roy. Astron. Soc. 290(1), 102–106 (1997).
https://doi.org/10.1093/mnras/290.1.102
16.P. S. Barklem, B. J. O’ Mara, and J. E. Ross, “The Broadening of d-f and f-d Transitions by Collisions with Neutral Hedrogen Atoms,” Mon. Notic. Roy. Astron. Soc. 296(4), 1057–1060 (1998).
https://doi.org/10.1046/j.1365-8711.1998.01484.x
17.S. Basu and H. M. Antia, “Constraining Solar Abundances Using Helioseismology,” Astrophys. J. Lett. 606(1), 85–88 (2004).
https://doi.org/10.1086/421110
18.U. Becker, P. Zimmermann, and H. Holweger, “Solar and Meteoritic Abundance of Silicon,” Geochim. Cosmochim. Acta 44, 2145–2149 (1980).
https://doi.org/10.1016/0016-7037(80)90210-0
19.N. Bello González, M. Flores Soriano, F. Kneer, et al., “Acoustic Waves in the Solar Atmosphere at High Spatial Resolution. II. Measurement in the Fe I 5434 Å Line,” Astron. Astrophys. 522, 1–8 (2010).
https://doi.org/10.1051/0004-6361/201014052
20.L. Delbouille, G. Roland, and L. Neven, Photometric atlas of the solar spectrum from λ 3000 to λ 10000 Å (L’Institut d’Astrophysiqué de l’Universite de Liège, Liège, 1973).
21.H. W. Drawin, “Zur Formelmäβigen Darstellung des Ionisierungsqerschnitts für den Atom-Atomstoβ und über die Ionen-Elektronen-Rekombination im dichten Neutralgas,” Z. Phys. 211(4), 404–417 (1968).
https://doi.org/10.1007/BF01379963
22.H. W. Drawin, “Influence of Atom-Atom Collisions on the Collisional-Radiative Ionization and Recombination Coefficients of Hydrogen Plasmas,” Z. Phys. 225(5), 483–493 (1969).
https://doi.org/10.1007/BF01392775
23.J. R. Fuhr, G. A. Martin, and W. L. Wiese, “Atomic Transition Probabilities. Iron Through Nickel,” J. Phys. Chem. Ref. Data 17(4) (1988).
24.T. Garz, “Absolute Oscillator Strength of Si I Lines Between 2500 Å and 8000 Å,” Astron. Astrophys. 26, 471–477 (1973).
25.N. Grevesse and A. J. Sauval, “Standard Solar Composition,” Space Sci. Rev. 85(1), 161–174 (1999) (in: Solar Composition and Its Evolution-from Core to Corona, Ed. by C. Frolich, M. C. E. Huber, and S. K. Solanki (Springer, 1999)).
https://doi.org/10.1023/A:1005161325181
26.H. R. Griem, Spectral Line Broadening by Plasmas, (Acad. Press, New York, 1974).
27.H. Holweger and E. A. Müller, “The Photosperic Barium Spectrum: Solar Abundance and Collision Broadening of Ba II Lines by Hydrogen,” Solar Phys. 39(1), 19–30 (1974).
https://doi.org/10.1007/BF00154968
28.E. V. Khomenko, R. I. Kostik, and N. G. Shchukina, “Five-Minute Oscillations Above Granules and Integranular Lines,” Astron. Astrophys. 369, 660–671 (2001).
https://doi.org/10.1051/0004-6361:20010129
29.R. I. Kostik, E. V. Khomenko, and N. G. Shchukina, “Solar Granulation from Photosphere to Low Chromosphere Observed in Ba II 4554 Å Line,” Astron. Astrophys. 506, 1405–1414 (2009).
https://doi.org/10.1051/0004-6361/200912441
30.K. Lodders, “Solar System Abundances and Condensation Temperatures of the Elements,” Astrophys. J. 591(2), 1220–1247 (2003).
https://doi.org/10.1086/375492
31.D. Mihalas, Stellar Atmospheres, 2nd. ed. (W.H. Freeman and Co, San Francisco, 1978).
32.N. G. Shchukina, V. L. Olshevsky, and E. B. Khomenko, “The Solar Ba II 4554 Å Line as a Doppler Diagnostic: NLTE Analysis in 3D Hydrodynamical Model,” Astron. Astrophys. 506, 1393–1404 (2009).
https://doi.org/10.1051/0004-6361/200912048
33.N. Shchukina and J. Trujillo Bueno, “The Iron Line Formaton Problem in Three-Dimensional Hydrodynamic Models of Solar-Like Photospheres,” Astrophys. J. 550(2), 970–990 (2001).
https://doi.org/10.1086/319789
34.N. Shchukina and J. Trujillo Bueno, “Three-Dimensional Radiative Transfer Modeling of the Polarization of the Solar Continuous Spectrum,” Astrophys. J. 694, 1364–1378 (2009).
https://doi.org/10.1088/0004-637X/694/2/1364
35.R. F. Stein and Å. Nordlund, “Simulations of Solar Granulation,” Astrophys. J. 342(1), L95–L98 (1989).
https://doi.org/10.1086/185493
36.R. F. Stein and A. Nordlund, “Topology of Convection Beneath the Solar Surface,” Astrophys. J. 499(2), 914–933 (1998).
https://doi.org/10.1086/305678
37.J. Trujillo Bueno, N. G. Shchukina, and A. Asensio Ramos, “A Substantial Amount of Hidden Magnetic Energy in the Quiet Sun,” Nature 404, 326–329 (2004).
https://doi.org/10.1038/nature02669
38.A. Unsöld, Physik der Sternatmosphären, 2nd ed. (Springer, Berlin, 1955).
https://doi.org/10.1007/978-3-642-47425-5
39.S. Wedemeyer, “Stand Photospheric Abundance of Silicon in the Sun and in Vega,” Astron. Astrophys. 373, 998–1008 (2001).
https://doi.org/10.1051/0004-6361:20010663