HD 41641: A classical δ Sct-type pulsator with chemical signatures of an Ap star^⋆,⋆⋆

¹ Institute of Astronomy, KU Leuven, Celestijnenlaan 200D, 3001 Leuven, Belgium
e-mail: ana.escorza@ster.kuleuven.be
² Institut d’Astronomie et d’Astrophysique, Université Libre de Bruxelles, Boulevard du Triomphe, 1050 Bruxelles, Belgium
³ Institute for Astro-and Particle Physics, University of Innsbruck, Technikerstrasse 25/8, 6020 Innsbruck, Austria
⁴ Institute of Astronomy, Russian Academy of Sciences, Pyatnistkaya 48, 119017 Moscow, Russia
⁵ LESIA, Observatoire de Paris, PSL Research University, CNRS, Sorbonne Universités, UPMC Univ. Paris 06, Univ. Paris Diderot, Sorbonne Paris Cité, 5 place Jules Janssen, 92195 Meudon, France
⁶ INAF-Osservatorio Astronomico di Brera, via E. Bianchi 46, 23807 Merate ( LC), Italy
⁷ Department of Astrophysics/IMAPP, Radboud University Nijmegen, PO Box 9010, 6500 GL Nijmegen, The Netherlands

Received: 1 December 2015
Accepted: 14 February 2016

Abstract

Context. Among the known groups of pulsating stars, δ Sct stars are one of the least understood. Theoretical models do not predict the oscillation frequencies that observations reveal. Complete asteroseismic studies are necessary to improve these models and better understand the internal structure of these targets.

Aims. We study the δ Sct star HD 41641 with the ultimate goal of understanding its oscillation pattern.

Methods. The target was simultaneously observed by the CoRoT space telescope and the HARPS high-resolution spectrograph. The photometric data set was analyzed with the software package PERIOD04, while FAMIAS was used to analyze the line profile variations. The method of spectrum synthesis was used for spectroscopically determining the fundamental atmospheric parameters and individual chemical abundances.

Results. A total of 90 different frequencies was identified and analyzed. An unambiguous identification of the azimuthal order of the surface geometry could only be provided for the dominant p-mode, which was found to be a nonradial prograde mode with m = +1. Using T_eff and log g, we estimated the mass, radius, and evolutionary stage of HD 41641. We find HD 41641 to be a moderately rotating, slightly evolved δ Sct star with subsolar overall atmospheric metal content and unexpected chemical peculiarities.

Conclusions. HD 41641 is a pure δ Sct pulsator with p-mode frequencies in the range from 10 d^-1 to 20 d^-1. This pulsating star presents chemical signatures of an Ap star and rotational modulation due to surface inhomogeneities, which we consider indirect evidence of the presence of a magnetic field.