Lanthanides and other spectral oddities in a Centauri⋆
Ce iii, Nd iii, Kr ii, and broad absorption features
Department of AstronomyUniversity of Michigan,
2 AIP, An der Sternwarte 16, 14482 Potsdam, Germany
3 Instituto de Ciencias Astronómicas, del la Tierra y del Espacio, Casilla 49, 5400 San Juan, Argentina
Received: 28 July 2010
Accepted: 25 September 2010
Context. There is considerable interest in the helium variable a Cen as a bridge between helium-weak and helium-strong CP stars.
Aims. We investigate Ce iii and other possible lanthanides in the spectrum the of hottest chemically peculiar (CP) star in which these elements have been found. A Kr ii line appears within a broad absorption which we suggest may be due to a high-level transition in C ii.
Methods. Wavelengths and equivalent widths are measured on high-resolution UVES spectra, analyzed, and their phase-variations investigated.
Results. New, robust identifications of Ce iii and Kr ii are demonstrated. Nd iii is likely present. A broad absorption near λ4619 is present at all phases of a Cen, and in some other early B stars.
Conclusions. The presence of lanthanides in a Cen strengthens the view that this star is a significant link between the cooler CP stars and the hotter helium-peculiar stars. Broad absorptions in a Cen are not well explained.
Key words: stars: chemically peculiar / stars: variable: general / stars: individual: a Cen
© ESO, 2010