BRITE photometry of the massive post-RLOF system HD149 404^⋆

¹ Space Sciences, Technologies and Astrophysics Research (STAR) Institute, Université de Liège, Allée du 6 Août, 19c, Bât B5c, 4000 Liège, Belgium
e-mail: g.rauw@uliege.be
² Instytut Astronomiczny, Uniwersytet Wrocławski, Kopernika 11, 51-622 Wrocław, Poland
³ Department of Physics and Astronomy, University of Delaware, Newark, DE 19716, USA
⁴ Nicolaus Copernicus Astronomical Center, Bartycka 18, 00-716 Warszawa, Poland
⁵ Département de Physique, Université de Montréal, CP 6128, Succ. Centre-Ville, Montréal PQ H3C 3J7, Canada
⁶ LESIA, Observatoire de Paris, Place Jules Janssen, 5, 92195 Meudon, France
⁷ AAVSO Headquarters, 49 Bay State Rd., Cambridge, MA 02138, USA
⁸ Instytut Automatyki, WydziałAutomatyki Elektroniki i Informatyki, Politechnika Śląska, Akademicka 16, 44-100 Gliwice, Poland
⁹ Department of Physics and Space Science, Royal Military College of Canada, PO Box 17000, Stn Forces, Kingston, Ontario K7K 7B4, Canada
¹⁰ Department of Astronomy and Astrophysics, University of Toronto, 50 St. George St., Toronto, Ontario M5S 3H4, Canada
¹¹ Institute for Astrophysics, University of Vienna, Türkenschanzstraße 17, 1180 Vienna, Austria
¹² Institute for Astro- and Particle Physics, University of Innsbruck, Technikerstrasse 25/8, 6020 Innsbruck, Austria

Received: 8 June 2018
Accepted: 23 October 2018

Abstract

Context. HD 149 404 is an evolved non-eclipsing O-star binary that has previously undergone a Roche lobe overflow interaction.

Aims. Understanding some key properties of the system requires a determination of the orbital inclination and of the dimensions of the components.

Methods. The BRITE-Heweliusz satellite was used to collect photometric data of HD 149 404. Additional photometry was retrieved from the SMEI archive. These data were analysed using a suite of period search tools. The orbital part of the lightcurve was modelled with the nightfall binary star code. The Gaia-DR2 parallax of HD 149 404 was used to provide additional constraints.

Results. The periodograms reveal a clear orbital modulation of the lightcurve with a peak-to-peak amplitude near 0.04 mag. The remaining non-orbital part of the variability is consistent with red noise. The lightcurve folded with the orbital period reveals ellipsoidal variations, but no eclipses. The minimum when the secondary star is in inferior conjunction is deeper than the other minimum due to mutual reflection effects between the stars. Combined with the Gaia-DR2 parallaxes, the photometric data indicate an orbital inclination in the range of 23°–31° and a Roche lobe filling factor of the secondary larger than or equal to 0.96.

Conclusions. The luminosity of the primary star is consistent with its present-day mass, whereas the more evolved secondary appears overluminous for its mass. We confirm that the primary’s rotation period is about half the orbital period. Both features most probably stem from the past Roche lobe overflow episode.