Determination of effective temperatures for G- and K-type giants and supergiants from observed photometric indices

1Lyubimkov, LS, 1Poklad, DB
1Crimean Astrophysical Observatory, Nauchny, Ukraine
Kinemat. fiz. nebesnyh tel (Online) 2014, 30(5):56-71
Start Page: Physics of Stars and Interstellar Medium
Language: Russian

We propose a method of the effective temperature Teff determination for G- and K-type giants and supergiants which is based on the use of two photometric indices that are free from interstellar extinction, namely, the index Q in the UBV photometric system and the index [c1] in the uvby system. Empirical relations are constructed between the Teff values derived for nearby and bright G and K-type giants and supergiants by the InfraRed Flux Method (IRFM), on the one hand, and the observed indices Q and [c1] for these stars, on the other hand. A systematic discrepancy is found between the Teff — Q relations for stars with the normal metallicity and with the lowered one. Approximating the constructed relations by the second-order polynomials, we obtain a relatively simple and, at once, rather accurate method of the Teff determination from the index Q in a range of 3800 ≤ Teff ≤ 5100 К and from the index [c1] in a range of 4900 ≤ Teff ≤ 5500 К.

Keywords: giants, supergiants, temperature

1.V. V. Kovtyukh, T. V. Mishenina, T. I. Gorbaneva, et al., “Determinations of high-precision effective temperatures for giants based on spectroscopic criteria,” Astron. Rep. 50, 134–142 (2006).

2.L. S. Lyubimkov, Chemical Composition of Stars: Method and Results of Analysis (Astroprint, Odessa, 1995) [in Russian].

3.L. S. Lyubimkov, T. M. Rachkovskaya, and D. B. Poklad, “Determining the fundamental parameters of F- and G-type supergiants,” Astrofizika 52, 237–256 (2009).

4.A. Alonso, S. Arribas, and C. Martinez-Roger, “The effective temperature scale of giant stars (F0-K5). I. The effective temperature determination by means of the IRFM,” Astron. Astrophys., Suppl. Ser. 139, 335–358 (1999).

5.D. E. Blackwell and A. E. Lynas-Gray, “Determination of the temperature of selected ISO flux calibration stars using the infrared flux method,” Astron. Astrophys., Suppl. Ser. 129, 505–515 (1998).

6.D. E. Blackwell, A. D. Petford, and M. J. Shallis, “Use of the infra-red flux method for determining stellar effective temperatures and angular diameters. The stellar temperature scale,” Astron. Astrophys. 82, 249–252 (1980).

7.F. Castelli and R. L. Kurucz, in Modeling of Stellar Atmospheres: Proceedings of the 210th Symposium of the International Astronomical Union, Uppsala, Sweden, 2002, Ed. by N. E. Piskunov, W. W. Weiss, and D. F. Gray (Astron. Soc. Pac., San Francisco, 2003).

8.A. Claret, “New grids of stellar models including tidal-evolution constants up to carbon burning. I. From 0.8 to 125 M ⊙ at Z = 0.02,” Astron. Astrophys. 424, 919–925 (2004).

9.A. Claret, “New grids of stellar models including tidal-evolution constants up to carbon burning. III. From 0.8 to 125 M ⊙: the Large Magellanic Cloud (Z = 0.007−0.01),” Astron. Astrophys. 453, 769–771 (2006).

10.B. Hauck and M. Mermilliod, “uvbyβ photoelectric photometric catalogue,” Astron. Astrophys., Suppl. Ser. 129, 431–433 (1998).

11.V. V. Kovtyukh, “High-Precision effective temperatures of 161 FGK supergiants from line-depth ratios,” Mon. Not. R. Astron. Soc. 378, 617–624 (2007).

12.L. S. Lyubimkov, D. L. Lambert, B. M. Kaminsky, et al., “Lithium abundance in atmospheres of F- and G-type supergiants and bright giants,” Mon. Not. R. Astron. Soc. 427, 11–26 (2012).

13.L. S. Lyubimkov, D. L. Lambert, S. A. Korotin, et al., “Nitrogen enrichment in atmospheres of A- and F-type supergiants,” Mon. Not. R. Astron. Soc. 410, 1774–1786 (2011).

14.L. S. Lyubimkov, D. L. Lambert, S. I. Rostopchin, et al., “Accurate fundamental parameters for A-, F- and G-type supergiants in the solar neighbourhood,” Mon. Not. R. Astron. Soc. 402, 1369–1379 (2010).

15.L. S. Lyubimkov, T. M. Rachkovskaya, S. I. Rostopchin, and D. L. Lambert, “Surface abundances of light elements for a large sample of early B-type stars. II. Basic parameters of 107 stars,” Mon. Not. R. Astron. Soc. 333, 9–26 (2002).

16.J.-C. Mermilliod and M. Mermilliod, Catalogue of Mean UBV Data on Stars (Springer-Verlag, New York, 1994).

17.A. Önehag, B. Gustafsson, K. Eriksson, and B. Edvardsson, “Calibration of Strömgren uvby-Hβ photometry for late-type stars-a model atmosphere approach,” Astron. Astrophys. 498, 527–542 (2009).

18.I. Ramirez and C. Allende Prieto, “Fundamental parameters and chemical composition of Arcturus,” Astrophys. J. 743, 135–148 (2011).

19.I. Ramirez and J. Melendez, “The effective temperature scale of FGK stars. I. Determination of temperatures and angular diameters with the infrared flux method,” Astrophys. J. 626, 446–464 (2005).

20.A. Richichi, L. Fabbroni, S. Ragland, and M. Scholz, “A homogeneous temperature calibration for K and Mgiants with an extension to the coolest stars,” Astron. Astrophys. 344, 511–520 (1999).

21.R. Trampedach, M. Asplund, R. Collet, et al., “A grid of three-dimensional stellar atmosphere models of solar metallicity. I. General properties, granulation, and atmospheric expansion,” Astrophys. J. 769, 18–32 (2013).

22.F. Van Leeuwen, Hipparcos, the New Reduction of the Raw Data (Springer, Dordrecht, 2007).