Open AccessA photometric and spectroscopic study of the brightest northern Cepheids — II. Fundamental physical parameters
Author(s) -
Kiss László L.,
Szatmáry Károly
Publication year - 1998
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 - 10.1046/j.1365-8711.1998.01943.x
Subject(s) - cepheid variable , physics , photometry (optics) , astrophysics , light curve , stars , effective temperature , astronomy , hertzsprung–russell diagram , stellar evolution
We present a new Cepheid reddening and effective temperature scale based on the uvby photometry published in the first paper of this series. Using all available information about the companion stars in Cepheids with bright blue secondaries, we remove their light from the observed light and colour curves. The resulting corrections are as large as 0.05–0.15 mag in several cases for different colour indices. A new photometric approach based on the ( b − y ) versus ( B − V ) two‐colour diagram is tested with three other previous calibrations taken from the literature. Two uvby relations in earlier studies turn out to be the most reliable and consistent, and so they are used in deriving colour excesses. We determine systematically higher reddenings for Cepheids with a significant secondary light correction. The dereddened Stro¨mgren colours are calibrated in terms of T eff and log g using the most recent synthetic colour grids. Our temperature scale is very close to that of Kraft, which is supported by other recent temperature determinations using the infrared flux method or Geneva photometry. The photometric gravities fit some of the earlier theoretical and observational (mainly spectroscopic) results very well.