Skip to main content

Abundances of α-Process Elements in Thin-Disk, Thick-Disk, and Halo Stars of the Galaxy: Non-LTE Analysis

Abstract

The atmospheric parameters and abundances of Mg, Si, Ca, and Ti have been determined for 20 stars using the Gaia DR2 parallaxes, high-resolution spectra, and modeling of lines without assuming LTE (non-LTE modeling). A sample of stars with homogeneous data on the abundances of α-process elements has thus been increased to 94. It is shown that applying a non-LTE approach and classical ID atmospheric models with spectroscopically determined gravitational accelerations (log g) based on Fe I and Fe II lines yields reliable results. Analysis of the full sample confirms the conclusions of earlier studies indicating excesses of Mg, Si, Ca, and Ti relative to Fe for halo and thick-disk stars, and strong excesses of these elements for thick-disk stars relative to stars with similar metallicities in the thin disk. New results are also obtained. The ratios [Mg/Fe], [Si/Fe], [Ca/Fe], and [Ti/Fe] in the thick disk remain constant and similar to each other at the level ~ 0.3 when [Fe/H] ≲ —0.4, and fall off when the metallicity becomes higher, suggesting the onset of the production of iron in Type la supernovae. Halo stars have the same [α/Fe] values independent of their distance (within ~ 8 kpc of the Sun), providing evidence for a universal character of the evolution of the abundances of α-process elements in different parts of the Galaxy. The excess abundances relative to iron for halo stars are, on average, the same and at the level ~ 0.3 dex for Mg, Si, Ca, and Ti. These data are important for refining nucleosynthesis models. The scatter of [α/Fe] increases for [Fe/H] ≲ —2.6, but the scatter of the ratios between the different α-process elements remains small, possibly indicating incomplete mixing of nucleosynthesis products during the formation of these stars.

This is a preview of subscription content, access via your institution.

References

  1. 1.

    G. Gilmore and N. Reid, Mon. Not. R. Astron. Soc. 202, 1025 (1983).

    ADS  Article  Google Scholar 

  2. 2.

    R. Gratton, E. Carretta, F. Matteucci, and C. Sneden, in Formation of the Galactic Halo... Inside and Out, Ed. by H. L. Morrison and A. Sarajedini, ASP Conf. Ser. 92, 307 (1996).

    ADS  Google Scholar 

  3. 3.

    K. Fuhrmann, Astron. Astrophys. 338, 161 (1998).

    ADS  Google Scholar 

  4. 4.

    L. Mashonkina and T. Gehren, Astron. Astrophys. 364, 249 (2000).

    ADS  Google Scholar 

  5. 5.

    T. Bensby, S. Feltzing, I. Lundstrom, and I. Ilyin, Astron. Astrophys. 433, 185 (2005).

    ADS  Article  Google Scholar 

  6. 6.

    V. Z. Adibekyan, S. G. Sousa, N. C. Santos, E. Del-gado Mena, J. I. Gonzalez Hernandez, G. Israelian, M. Mayor, and G. Khachatryan, Astron. Astrophys. 545, A32 (2012).

    Article  Google Scholar 

  7. 7.

    T. Bensby, S. Feltzing, and M. S. Oey, Astron. Astrophys. 562, A71 (2014).

  8. 8.

    R. Cayrel, E. Depagne, M. Spite, V. Hill, et al., Astron. Astrophys. 416, 1117 (2004).

    ADS  Article  Google Scholar 

  9. 9.

    P. Bonifacio, M. Spite, R. Cayrel, V. Hill, et al., Astron. Astrophys. 501, 519 (2009).

    ADS  Article  Google Scholar 

  10. 10.

    J. G. Cohen, N. Christlieb, I. Thompson, A. McWilliam, S. Shectman, D. Reimers, L. Wisotzki, and E. Kirby, Astrophys. J. 778, 56 (2013).

    ADS  Article  Google Scholar 

  11. 11.

    D. Yong, J. E. Norris, M. S. Bessell, N. Christlieb, et al., Astrophys. J. 762, 26 (2013).

    ADS  Article  Google Scholar 

  12. 12.

    M. Bergemann, R. Collet, R. Schonrich, R. Andrae, M. Kovalev, G. Ruchti, C. J. Hansen, and Z. Magic, Astrophys. J. 847, 16 (2017); arXiv:1612.07363v2.

    ADS  Article  Google Scholar 

  13. 13.

    S. Randich, G. Gilmore, and Gaia-ESO Consortium, The Messenger 154, 47 (2013).

    ADS  Google Scholar 

  14. 14.

    A. Recio-Blanco, P. de Laverny, G. Kordopatis, A. Helmi, et al., Astron. Astrophys. 567, id. A5 (2014).

  15. 15.

    S. R. Majewski, R. P. Schiavon, P. M. Frinchaboy, C. Allende Prieto, et al., Astron. J. 154, 94 (2017).

    ADS  Article  Google Scholar 

  16. 16.

    S. Buder, M. Asplund, L. Duong, J. Kos, et al., Mon. Not. R. Astron. Soc. 478, 4513 (2018).

    ADS  Article  Google Scholar 

  17. 17.

    S. Buder, K. Lind, M. K. Ness, M. Asplund, et al., Astron. Astrophys. 624, id. A19 (2019).

  18. 18.

    M. N. Ishigaki, M. Chiba, and Aoki, Astrophys. J. 753, 64 (2012).

    ADS  Article  Google Scholar 

  19. 19.

    T. Sitnova, G. Zhao, L. Mashonkina, Y. Chen, et al., Astrophys. J. 808, 148 (2015).

    ADS  Article  Google Scholar 

  20. 20.

    G. Zhao, L. Mashonkina, H. L. Yan, S. Alexeeva, et al., Astrophys. J. 833, 225 (2016).

    ADS  Article  Google Scholar 

  21. 21.

    L. Mashonkina, P. Jablonka, Y. Pakhomov, T. Sitnova, and P. North, Astron. Astrophys. 604, id. A129 (2017).

  22. 22.

    L. Mashonkina, P. Jablonka, T. Sitnova, Y. Pakhomov, and P. North, Astron. Astrophys. 608, id. A89 (2017).

  23. 23.

    A. G. A. Brown, A. Vallenari, T. Prusti, J. H. J. de Bruijne, et al., Astron. Astrophys. 616, id. Al (2018).

  24. 24.

    K. Fuhrmann, Astron. Nachr. 325, 3 (2004).

    ADS  Article  Google Scholar 

  25. 25.

    T. Prusti, J. H. J. de Bruijne, A. G. A. Brown, A. Vallenari, et al., Astron. Astrophys. 595, Al (2016).

  26. 26.

    F. van Leeuwen, Astron. Astrophys. 474, 653 (2007).

    ADS  Article  Google Scholar 

  27. 27.

    G. A. Gontcharov, Astron. Lett. 32, 759 (2006).

    ADS  Article  Google Scholar 

  28. 28.

    B. Famaey, A. Jorissen, X. Luri, M. Mayor, S. Udry, H. Dejonghe, and C. Turon, Astron. Astrophys. 430, 165 (2005).

    ADS  Article  Google Scholar 

  29. 29.

    T. V. Mishenina, C. Soubiran, V. V. Kovtyukh, and S. A. Korotin, Astron. Astrophys. 418, 551 (2004).

    ADS  Article  Google Scholar 

  30. 30.

    L. Casagrande, I. Ramirez, J. Melendez, M. Bessell, and M. Asplund, Astron. Astrophys. 512, id. A54 (2010).

  31. 31.

    L. Casagrande, R. Schonrich, M. Asplund, S. Cassisi, I. Ramirez, J. Melendez, T. Bensby, and S. Feltzing, Astron. Astrophys. 530, A138 (2011).

  32. 32.

    A. Alonso, S. Arribas, and C. Martinez-Roger, Astron. Astrophys. 297, 197 (1995).

    ADS  Google Scholar 

  33. 33.

    C. A. L. Bailer-Jones, J. Rybizki, M. Fouesneau, G. Mantelet, and R. Andrae, Astron. J. 156, 58 (2018).

    ADS  Article  Google Scholar 

  34. 34.

    A. Alonso, S. Arribas, and C. Martinez-Roger, Astron. Astrophys. Suppl. Sen 140, 261 (1999).

    ADS  Article  Google Scholar 

  35. 35.

    J. I. Gonzalez Hernandez and P. Bonifacio, Astron. Astrophys. 497, 497 (2009).

    ADS  Article  Google Scholar 

  36. 36.

    I. Ramirez and J. Melendez, Astrophys. J. 626, 446 (2005).

    ADS  Article  Google Scholar 

  37. 37.

    E. Masana, C. Jordi, and I. Ribas, Astron. Astrophys. 450, 735 (2006).

    ADS  Article  Google Scholar 

  38. 38.

    A. Alonso, S. Arribas, and C. Martinez-Roger, Astron. Astrophys. Suppl. Sen 139, 335 (1999).

    ADS  Article  Google Scholar 

  39. 39.

    L. Mashonkina, T. Gehren, J.-R. Shi, A. J. Korn, and F. Grupp, Astron. Astrophys. 528, A87 (2011).

  40. 40.

    H. W. Drawin, Zeitschr. Phys. 225, 483 (1969).

    ADS  Google Scholar 

  41. 41.

    L. Mashonkina, T. Sitnova, and A. K. Belyaev, Astron. Astrophys. 605, id. A53 (2017).

  42. 42.

    A. Mitrushchenkov, M. Guitou, A. K. Belyaev, S. A. Yakovleva, A. Spielfiedel, and N. Feautrier, J. Chem. Phys. 146, 014304 (2017).

    ADS  Article  Google Scholar 

  43. 43.

    L. Mashonkina, Astron. Astrophys. 550, A28 (2013).

  44. 44.

    T. M. Sitnova, Astron. Lett. 42, 734 (2016).

    ADS  Article  Google Scholar 

  45. 45.

    K. Butler and J. Giddings, Newslett. Anal. Astron. Spectra, No. 9 (1985).

  46. 46.

    V. Tsymbal, T. A. Ryabchikova, and T. Sitnova, in Physics of Magnetic Stars, Ed. by I. I. Romanyuk, I. A. Yakunin, and D. O. Kudryavtsev (2019, in press).

    Google Scholar 

  47. 47.

    T. Ryabchikova, N. Piskunov, R. L. Kurucz, H. C. Stempels, U. Heiter, Y Pakhomov, and P. S. Barklem, Phys. Scripta 90, 054005 (2015).

    ADS  Article  Google Scholar 

  48. 48.

    B. Gustafsson, B. Edvardsson, K. Eriksson, U. G. Jorgensen, A. Nordlund, and B. Plez, Astron. Astrophys. 486, 951 (2008).

    ADS  Article  Google Scholar 

  49. 49.

    J. A. Valenti and N. Piskunov, Astrophysics Source Code Library, No. 1202.013 (2012).

  50. 50.

    R. L. Kurucz, I. Furenlid, J. Brault, and L. Testerman, Solar Flux Atlas from 296 to 1300 nm (Natl. Solar Observatory, New Mexico, 1984).

    Google Scholar 

  51. 51.

    S. K. Yi, P. Demarque, and Y.-C. Kim, Astrophys. Space Sci. 291, 261 (2004).

    ADS  Article  Google Scholar 

  52. 52.

    D. Maoz, F. Mannucci, and T. D. Brandt, Mon. Not. R. Astron. Soc. 426, 3282 (2012).

    ADS  Article  Google Scholar 

  53. 53.

    L. Mashonkina, T. Gehren, C. Travaglio, and T. Borkova, Astron. Astrophys. 397, 275 (2003).

    ADS  Article  Google Scholar 

  54. 54.

    D. Romano, A. I. Karakas, M. Tosi, and F. Matteucci, Astron. Astrophys. 522, A32 (2010).

  55. 55.

    C. Sneden, J. J. Cowan, C. Kobayashi, M. Pignatari, J. E. Lawler, E. A. Den Hartog, and M. P. Wood, Astrophys. J. 817, 53(2016).

  56. 56.

    T. M. Sitnova and L. I. Mashonkina, Astron. Lett. 44, 411 (2018).

    ADS  Article  Google Scholar 

Download references

Acknowledgments

We thank Klaus Fuhrmann for kindly presenting us with spectra obtained on the 2.2 m telescope of the Calar Alto Observatory with the FOCES spectrograph. This study has made use of the AD S ADS,5 SIMBAD, MARCS, and VALD databases.

Author information

Affiliations

Authors

Corresponding authors

Correspondence to L. I. Mashonkina, M. D. Neretina, T. M. Sitnova or Yu. V. Pakhomov.

Additional information

Russian Text © The Author(s), 2019, published in Astronomicheskii Zhurnal, 2019, Vol. 96, No. 9, pp. 721–734.

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Mashonkina, L.I., Neretina, M.D., Sitnova, T.M. et al. Abundances of α-Process Elements in Thin-Disk, Thick-Disk, and Halo Stars of the Galaxy: Non-LTE Analysis. Astron. Rep. 63, 726–738 (2019). https://doi.org/10.1134/S1063772919090063

Download citation