Lanthanides and other spectral oddities in a Centauri

COWLEY, C. R.; HUBRIG, S.; GONZALEZ, J. F.

ASTRONOMY AND ASTROPHYSICS

EDP SCIENCES S A

Año: 2010 vol. 523 p. 82 - 86

0004-6361

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. Based on observations collected at the European Southern Observatory, Paranal, Chile (ESO programmes 65.L-0316(A), 073.D-0504(A), and 076.B-0055(A)).