The spectroscopic variability ofTeffand log gin the hot pulsating star β Cephei

Time resolved spectra of β Cep yield the following average results: T eff = 24000 ± 250 K, log g = 3.91 ± 0.05 and ζ =8.1 ± 0.9 km s -1 . Nitrogen, oxygen, neon, aluminium, silicon and sulfur abundances are solar while carbon, magnesium and iron are slightly underabundant. Pulsational amplitudes of ∇T eff ∼ 700 K and Alog g ∼ 0.2 dex are found from Hβ. The metal lines give similar amplitudes but centred on T eff ∼ 25 000 K. An upper limit of 1.0 km s -1 to the variability of the microturbulence is derived from the Si III triplet at 455 nm. The radial-velocity amplitude derived from the core of Hβ is ∼15 per cent greater than that from the metal lines.