Open AccessHigh‐precision effective temperatures of 215 FGK giants from line‐depth ratios
Author(s) -
Kovtyukh V. V.,
Soubiran C.,
Bienaymé O.,
Mishenina T. V.,
Belik S. I.
Publication year - 2006
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1111/j.1365-2966.2006.10719.x
Subject(s) - physics , metallicity , effective temperature , astrophysics , calibration , line (geometry) , spectral line , spectral resolution , equivalent width , surface gravity , spectrometer , range (aeronautics) , stars , astronomy , emission spectrum , optics , geometry , mathematics , materials science , quantum mechanics , composite material
We present precise effective temperatures ( T eff ) of 215 FGK giants determined using the method of line‐depth ratios. For each star, we have measured the line depths and equivalent widths of a large number of spectral lines of low and high excitation potentials and established ∼100 relations between T eff and their ratios. Starting with an initial value T eff , the relations are then self‐calibrated by an iterative process. Our final estimates have been compared with very accurate (1 per cent) published temperatures and show a good agreement. Using our calibrations, we derive precise temperatures for 215 giants with near‐solar metallicity, from high‐resolution ( R = 42 000) and high signal‐to‐noise ratio (S/N = 100–250) echelle spectra, obtained with the ELODIE spectrometer at the Observatoire de Haute Provence (OHP). The range of application of the method is 3500–5700 K (G0 III–K4 III). The internal error for a single calibration is less than 95 K, while the combination of all 100 calibrations reduces the uncertainty to only 5–20 K (1σ). A big advantage of the line ratio method is its independence of interstellar reddening, and its modest sensitivity to spectral resolution, abundance, macroturbulence and other factors.