Research Note

The multiplicity of φ Phe revisited

¹ Institut d’Astronomie et d’Astrophysique, Université Libre de Bruxelles (ULB), 1050 Bruxelles, Belgium
e-mail: pourbaix@astro.ulb.ac.be
² ESO, Alonso de Córdova 3107 Vitacura, Casilla 19001, Santiago, Chile
³ Astronomisches Institut, Ruhr–Universität Bochum, Universitätsstrasse 150, 44780 Bochum, Germany
⁴ Institudo de Astronomia, Universidad Católica del Norte, Antofagasta, Chile

Received: 15 April 2013
Accepted: 29 April 2013

Abstract

Aims. The chemically peculiar B star φ Phe was, until very recently, considered to be a triple system, even though the data were not conclusive and the orbits rather uncertain. Very recent results provided a revised orbit, different from the then available astrometric Hipparcos orbit.

Methods. Additional spectroscopic data obtained with the BESO spectrograph at Cerro Armazones confirm the newly found orbit, even though the resulting radial velocities do not allow one to improve on the recent orbit. We combined this with the Hipparcos measurements to secure the astrometric orbit, and derived the inclination of the system. Using evolutionary tracks, we can finally constrain all parameters of the two components in this system.

Results. We confirm the mass of the primary, 3 M_⊙, and find that the companion has a mass of 0.9 M_⊙. The inclination of the system is i = 93° ± 4.7°, and it is potentially eclipsing; we predict the time of the next conjunction. Given that the eccentricity of the orbit and the exact value of the semi-amplitude of the radial velocity relies on just one set of points, we also urge observers to measure radial velocities at the next periastron passage in April 2015.