Accurate luminosities for F-G supergiants from FeII/FeI line depth ratios

V. V. Kovtyukh (1) , F. A. Chekhonadskikh (1) , R. E. Luck (2) , C. Soubiran (3, 4, 5, 6) , M. P. Yasinskaya , S. I. Belik (7)

1 Astronomical observatory of Odessa National University [Odessa]
2 Department of Astronomy, Case Western Reserve University,
3 OASU - Observatoire aquitain des sciences de l'univers
4 LAB - Laboratoire d'Astrophysique de Bordeaux [Pessac]
5 UB - Université Sciences et Technologies - Bordeaux 1
6 L3AB - Laboratoire d'astrodynamique, d'astrophysique et d'aéronomie de bordeaux
7 Odessa Astronomical Observatory

Luminous FG supergiants can be used as extragalactic distance indicators. In order to fully exploit the properties of these bright stars, we must first learn how to measure their luminosities. Based primarily on classical Cepheids and supergiants in clusters and OB associations, we have derived 80 empirical relations connecting the line depth ratios of FeII/FeI lines with the absolute magnitudes Mv and the effective temperatures Teff. These relations have been applied to estimate the absolute magnitudes of 98 FG supergiants with an error of +/-0.26mag. The application range of our calibrations is spectral types F2-G8 and luminosity classes I and II (absolute magnitudes Mv, -0.5 to -8 mag). A comparison of our Mv determinations with values from the literature shows good agreement.

Mots clés: stars: fundamental parameters; supergiants; stars: variables: Cepheids

Domaines: Instrumentation et méthodes pour l'astrophysique [astro-ph.IM]; Instrumentation et méthodes pour l'astrophysique [astro-ph.IM]; Planète et Univers [physics]

V. V. Kovtyukh, F. A. Chekhonadskikh, R. E. Luck, C. Soubiran, M. P. Yasinskaya, et al.. Accurate luminosities for F-G supergiants from FeII/FeI line depth ratios. Monthly Notices of the Royal Astronomical Society, 2010, 408, pp.1568-1575. ⟨10.1111/J.1365-2966.2010.17217.X⟩. ⟨hal-00521973⟩