Variability of the He I λ5876 Å line in early type chemically peculiar stars. II

Abstract

To try to understand the behavior of helium variability in Chemically Peculiar stars, we continued our on-going observational campaign started by \cite{catanzaro99}. In this paper we present a new set of time resolved spectroscopic observations of the He I 5876 Å line for a sample of 10 stars in the spectral range B3 - A2 and characterized by different overabundances.

This line does not show variability in two stars: HD 77350 and HD 175156. It shows instead an equivalent width variation in phase with the Hipparcos light curve for two stars: HD 79158 and HD 196502. Antiphase variations have been found in 4 stars of our sample, namely: HD 35502, HD 124224, HD 129174 and HD 142990. Nothing we can say about HD 115735 because of the constancy of Hipparcos photometric data, while no phase relation has been observed for HD 90044.

In the text we discuss the case of HD 175156, according to photometric calibration and our spectroscopic observations we rule out the membership of this star to the main sequence chemically peculiar stars.

We confirm the results obtained in the previous paper for which phase relations between light, spectral and magnetic variations are not dependent on stellar spectral type or peculiarity subclass.

Based on observations collected at stellar station ``M. G. Fracastoro'' of the Catania Astrophysical Observatory and on observations collected at Complejo Astrónomico El Leoncito (Casleo), which is operated under agreement between the Consejo Nacional de Investigationes Cientifícas y Técnicas (CONICET) and the National Universities of La Plata, Córdoba and San Juan.