Research Note

Scandium in AmFm stars in the light of new atomic data

¹ LUTH, Observatoire de Paris, CNRS, Université Paris Diderot, 5 place Jule Janssen, 92190 Meudon, France
e-mail: georges.alecian@obspm.fr
² Département de Physique et d’Astronomie, Université de Moncton, Moncton, NB, E1A 3E9, Canada
e-mail: francis.leblanc@umoncton.ca
³ Université de Lyon, 69003, Université Lyon 1, Observatoire de Lyon, 9 avenue Charles André, 69230 Saint-Genis Laval, France
⁴ CNRS, UMR 5574, , Centre de Recherche Astrophysique de Lyon, École Normale Supérieure de Lyon, 69007 Lyon, France
e-mail: gmassacr@ens-lyon.fr

Received: 23 January 2013
Accepted: 24 April 2013

Abstract

Context. The abundance anomalies observed in AmFm stars are believed to be caused by atomic diffusion below the superficial convection zone. The process by which these anomalies, which are produced in deep layers, propagate toward the stellar surface is well understood. However, it depends on quantities which are not directly observed: the mass-loss flux and the exact position of convections zones. Scandium, which is systematically underabundant at the surface of AmFm stars, is a key element in understanding the interplay between atomic diffusion and the stellar structure and how this structure evolves with time.

Aims. In the light of a new extensive set of atomic data, we calculate much more accurate radiative accelerations of Sc than previously done in the aim to better understand the observed abundance anomalies of this element in AmFm stars.

Methods. Two methods are employed to obtain these radiative accelerations based on the so-called SVP (single-valued parameters) parametric method and the GLAM method while employing this new atomic data.

Results. The radiative accelerations, shown here in a typical Am stellar model, are discussed in the light of the observed anomalies of Sc. Our results are more compatible with the scenario where the scandium depletion is created below the hydrogen convection zone.