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Astron. Astrophys. 324, 1096-1104 (1997)

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The line-profile variable [FORMULA] Scorpii is a spectroscopic triple system *

K. De Mey 1, C. Aerts 1, **, C. Waelkens 1, S.R. Cranmer 2, C. Schrijvers 3, J.H. Telting 4, K. Daems 1, *** and G. Meeus 1

1 Instituut voor Sterrenkunde, Katholieke Universiteit Leuven, Celestijnenlaan [FORMULA] B, B-3001 Heverlee, Belgium
2 Smithsonian Astrophysical Observatory, 60 Garden Street, MS 50, Cambridge, MA 02138, USA
3 Astronomical Institute Anton Pannekoek, University of Amsterdam, Kruislaan 403, 1098 SJ Amsterdam, The Netherlands
4 Netherlands Foundation for Research in Astronomy, Isaac Newton Group of Telescopes, Apartado 321, E-38780 Santa Cruz de La Palma, Spain

Received 3 January 1997 / Accepted 4 March 1997

Abstract

An analysis of 278 spectra of the line-profile variable [FORMULA] Scorpii leads to the following conclusions.

[FORMULA] Sco is the primary of a binary system. The radial-velocity variations have a peak-to-peak amplitude of [FORMULA] 60 km/s and an orbital period of 5.959 days. The orbit is not circular but has an eccentricity of 0.29. The [FORMULA].959-binary system probably moves in orbit with another distant, as yet unknown third star.

By means of three five-hour time series of high-resolution spectra, the oscillations of the rapidly rotating [FORMULA] Cephei-type main component are investigated. Line-profile variations, which reveal travelling subfeatures across the lines, are discovered. [FORMULA] Sco is so far one of the very few [FORMULA] Cephei stars in which such a moving-bump phenomenon is detected. Radial-velocity variations are derived from the data and analysed to reveal a main oscillation frequency near 4.66 cycles day-1, and some more candidate frequencies. [FORMULA] Sco is a non-radially pulsating [FORMULA] Cephei star which rotates supersynchronously.

The characteristics of [FORMULA] Sco and the [FORMULA] Oph stars are briefly addressed. Despite the common line-profile behaviour, spectral type, and [FORMULA], we find no evidence of circumstellar material around [FORMULA] Sco.

Key words: stars: binaries: spectroscopic – stars: oscillations – stars: individual: Scorpii – line: profiles

* Based on observations collected at the European Southern Observatory, La Silla, Chile.
** Postdoctoral Fellow, Fund for Scientific Research, Flanders
*** Research Assistant, Fund for Scientific Research, Flanders

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© European Southern Observatory (ESO) 1997

Online publication: May 5, 1998

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