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|
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|
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