Advertisement

Solar Physics

, 294:63 | Cite as

Solar Center–limb Variation of the Strengths of Spectral Lines: Classification and Interpretation of Observed Trends

  • Y. TakedaEmail author
  • S. UeNo
Article

Abstract

The equivalent widths (\(W\)) of 565 spectral lines in the wavelength range of 4690 – 6870 Å were evaluated at 31 consecutive points from the solar disk center (\(\mu \equiv \cos \theta = 1\)) to near the limb (\(\mu = 0.25\)) by applying the synthetic spectrum-fitting technique, in order to clarify the nature of their center–limb variations, especially the observed slope differing from line to line and its interpretation in terms of line properties. We found that the distribution of the gradient \(\beta \)\((\equiv -\mathrm{d}\log W/ {\mathrm{d}}\log \mu )\) well correlates with that of the \(\mathrm{d} \log W/{\mathrm{d}}\log T\) index, which means that the center-to-limb variation of \(W\) is determined mainly by the \(T\)-sensitivity of individual lines because the line-forming region shifts towards upper layers of lower \(T\) as we go toward the limb. Furthermore, the key to understanding the behavior of \(\mathrm{d}\log W/{\mathrm{d}}\log T\) (depending on the temperature sensitivity of number population) is whether the considered species is in minor population stage or major population stage, by which the distribution of \(\beta \) is explained in terms of differences in excitation potential and line strengths. All the center–limb data of equivalent widths (as well as line-of-sight turbulent velocity dispersions, elemental abundances, and mean line-formation depths derived as by-products) along with the solar spectra used for our analysis are made available as on-line materials.

Keywords

Center–limb observations Spectral line, intensity and diagnostics Spectrum, visible Velocity fields, photosphere 

Notes

Disclosure of Potential Conflicts of Interest

The authors declare that they have no conflicts of interest.

Supplementary material

11207_2019_1455_MOESM1_ESM.zip (22.9 mb)
(zip 22.8 MB)

References

  1. Allende Prieto, C., Asplund, M., Fabiani Bendicho, P.: 2004, Astron. Astrophys. 423, 1109. DOI. ADSCrossRefGoogle Scholar
  2. Balthasar, H.: 1988, Astron. Astrophys. Suppl. Ser. 72, 473. ADSGoogle Scholar
  3. Canfield, R.C., Beckers, J.M.: 1976, Colloques Internationaux du CNRS (AFCRL-TR-0592, part 2). Cayrel, R., Steinberg, M. (eds.), 250, 291. Google Scholar
  4. Elste, G.: 1986, Solar Phys. 107, 47. DOI. ADSCrossRefGoogle Scholar
  5. Gray, D.F.: 1988, Lectures on Spectral-Line Analysis: F, G, and K Stars, Arva, Ontario. Google Scholar
  6. Gurtovenko, E.A., Kostyk, R.I., Orlova, T.V., Troian, V.I., Fedorchenko, G.L.: 1975, Profiles of Selected Fraunhofer Lines for Different Positions Center-Limb on the Solar Disk, Naukova Dumka, Kiev (in Russian). Google Scholar
  7. Gurtovenko, E.A., Ratnikova, V.A.: 1976, Astrom. Astrofis. 30, 14. ADSGoogle Scholar
  8. Holweger, H.: 1967, Z. Astrophys. 65, 365. ADSGoogle Scholar
  9. Jevremović, D., Vince, I., Erkapić, S., Popović, L.: 1993, Publ. Obs. Astron. Belgrade 44, 33. ADSGoogle Scholar
  10. Kostik, R.I.: 1982, Solar Phys. 78, 39. DOI. ADSCrossRefGoogle Scholar
  11. Kurucz, R.L.: 1993, Kurucz CD-ROM No. 13, Harvard-Smithsonian Center for Astrophysics, Cambridge. Google Scholar
  12. Kurucz, R.L., Bell, B.: 1995, Kurucz CD-ROM No. 23, Harvard-Smithsonian Center for Astrophysics, Cambridge. Google Scholar
  13. Lind, K., et al.: 2017, Mon. Not. Roy. Astron. Soc. 4(68), 4311. DOI. ADSCrossRefGoogle Scholar
  14. Meylan, T., Furenlid, I., Wiggs, M.S., Kurucz, R.L.: 1993, Astrophys. J. Suppl. 85, 163. DOI. ADSCrossRefGoogle Scholar
  15. Meléndez, J., Asplund, M.: 2008, Astron. Astrophys. 490, 817. DOI. ADSCrossRefGoogle Scholar
  16. Moore, C.E., Minnaert, M.G.J., Houtgast, J.: 1966, The Solar Spectrum 2935 A to 8770 A, National Bureau of Standards Monograph/US Government Printing Office, Washington. Google Scholar
  17. Nakai, Y., Hattori, A.: 1985, Mem. Fac. Sci., Kyoto Univ., Ser. Phys. Astrophys. Geophys. Chem. 36, 385. Google Scholar
  18. Neckel, H.: 1994, In: Pap, J.M., Frolich, C., Hudson, H.S., Solanki, S. (eds.) The Sun as a Variable Star, Solar and Stellar Irradiance Variations, IAU Coll. 143, Cambridge University Press, Cambridge, 37. Google Scholar
  19. Neckel, H.: 1999, Solar Phys. 184, 421. ADSCrossRefGoogle Scholar
  20. Nissen, P.E.: 1965, Ann. Astrophys. 28, 556. ADSGoogle Scholar
  21. Pereira, T.M.D., Asplund, M., Kiselman, D.: 2009, Astron. Astrophys. 5(08), 1403. DOI. ADSCrossRefGoogle Scholar
  22. Rodríguez Hidalgo, I., Collados, M., Vázquez, M.: 1994, Astron. Astrophys. 283, 263. ADSGoogle Scholar
  23. Rutten, R.J., van der Zalm, E.B.J.: 1984a, Astron. Astrophys. Suppl. Ser. 55, 143. ADSGoogle Scholar
  24. Rutten, R.J., van der Zalm, E.B.J.: 1984b, Astron. Astrophys. Suppl. Ser. 55, 171. ADSGoogle Scholar
  25. Takeda, Y.: 1995, Publ. Astron. Soc. Japan 47, 287. ADSGoogle Scholar
  26. Takeda, Y., Ohkubo, M., Sadakane, K.: 2002, Publ. Astron. Soc. Japan 54, 451. DOI. ADSCrossRefGoogle Scholar
  27. Takeda, Y., Sato, B., Omiya, M., Harakawa, H.: 2015, Publ. Astron. Soc. Japan 67, 24. DOI. ADSCrossRefGoogle Scholar
  28. Takeda, Y., UeNo, S.: 2014, Publ. Astron. Soc. Japan 66, 32. DOI. ADSCrossRefGoogle Scholar
  29. Takeda, Y., UeNo, S.: 2017a, Publ. Astron. Soc. Japan 69, 46. DOI. ADSCrossRefGoogle Scholar
  30. Takeda, Y., UeNo, S.: 2017b, Solar Phys. 292, 123. DOI. ADSCrossRefGoogle Scholar

Copyright information

© Springer Nature B.V. 2019

Authors and Affiliations

  1. 1.National Astronomical Observatory of JapanMitaka, TokyoJapan
  2. 2.SOKENDAIThe Graduate University for Advanced StudiesMitaka, TokyoJapan
  3. 3.Kwasan and Hida ObservatoriesKyoto UniversityTakayama, GifuJapan

Personalised recommendations