The effective temperatures and colours of G and K stars

Temperature scales are found for G and K dwarf and giant stars, using new tables of synthetic infrared colours as well as the infrared flux ratio method. The temperatures of 95 individual stars are given. The colours are presented for grids of flux constant, line blanketed models. One grid has been published previously, as have some colours for the visible region of the spectrum. The models of this grid are in the range $$4000\enspace\text K \lt T_\text{eff} \lt 6000\enspace\text K, 0.75 \lt\text {log}\enspace g \lt 3.00, - 3.0 \lt [\text {A/H}] \lt 0.0$$. A grid of dwarf models, with the same temperature and abundance range but with $$3.75 \lt\text log\enspace g \lt 4.5$$ is also used. The colours are computed from two scries of overlapping synthetic spectra, which have been calculated with a resolution of 0.1 Å between 3000 and 12000 Å and 1.0 Å between 0.9 and 6.0 μm. The following colours and magnitudes are presented: Glass $$J-H,\enspace H-K,\enspace K-L$$ and K; Cohen, Frogel & Persson $$J-H,\enspace H-K,\enspace K-L$$ and K; Johnson $$V-J,\enspace V-K,\enspace V-L$$ and K; Cousins $$V-R,\enspace R-I;$$ Johnson & Mitchell 13-colour and Wing's near-infrared eight-colour photometry. The colours are given relative to Vega. Near-infrared synthetic scans, using Oke's 50 Å bandpasses, are also given. In an appendix, transformation equations between several of the different systems are compared with those found from observational data.