Magnetic field measurements of Ap stars

Discovery of a strong magnetic field in HD 18610

¹ Institute for Astronomy (IfA), University of Vienna, Türkenschanzstrasse 17, 1180 Wien, Austria
² Institute of Astronomy, Russian Academy of Sciences, Pyatnitskaya 48, 109017 Moscow, Russia

Corresponding author: Ch. Stütz, stuetz@tycho.astro.univie.ac.at

Received: 5 July 2002
Accepted: 12 February 2003

Abstract

HD 18610 was included in our project on abundance determination of rapidly oscillating (roAp) and non–oscillating (noAp) cool chemically peculiar stars. Already a preliminary investigation of the raw spectra indicated the presence of an intense magnetic field which was confirmed by a more detailed analysis.
To determine the magnetic field strength we primarily used the Fe ii line at 6149.26 Å, a strong line which is split in a anomalous Zeeman doublet. HD 18610 is a Cr–Eu–Sr non-pulsating Ap star with a T_eff and  typical for roAp stars. The classification of this star as a CP2 star (Preston [CITE]) was confirmed with Δa photometry by Maitzen & Vogt ([CITE]). In the present investigation we derived a mean magnetic field modulus of G.