On the possible presence of promethium in the spectra of HD 101065 (Przybylski's star) and HD 965^*

¹ Department of Astronomy, University of Michigan, Ann Arbor, MI 48109-1010, USA
² Department of Astronomy, Case Western Reserve University, Cleveland, OH 44106-7215, USA
³ European Southern Observatory, Casilla 19001, Santiago 19, Chile e-mail: [shubrig; gmathys]@eso.org
⁴ Department of Natural Sciences, University of Michigan-Dearborn, Dearborn, MI 48128-1491, USA e-mail: dbord@umd.umich.edu

Corresponding author: C. R. Cowley, cowley@umich.edu

Received: 21 November 2003
Accepted: 23 February 2004

Abstract

Traditional and statistical line-identification methods indicate the presence of Pm I and II, Tc I, and perhaps Tc II in the spectrum of the roAp star HD 101065. These methods also lead to the presence of Pm II and probably also Pm I in a related cool Ap star, HD 965. The spectroscopic evidence is strong enough that we would declare promethium to be present without hesitation, if any of its isotopes were stable. The longest-lived promethium isotope has a half-life of only 17.7 years. The presence of this element would mean that unrecognized processes – perhaps flare activities – are taking place in the atmospheres of these stars. The significance of such processes for galactic chemical evolution cannot be ruled out. We discuss the possibility that the highly improbable wavelength coincidences are due to chance, or due to contamination of the laboratory sources.