The most massive heartbeat: an in-depth analysis of ι Orionis

• Published in: Monthly notices of the Royal Astronomical Society 2017-05, Vol.467 (2), p.2494-2503
• Main Authors: Pablo, Herbert, Richardson, N. D., Fuller, J., Rowe, J., Moffat, A. F. J., Kuschnig, R., Popowicz, A., Handler, G., Neiner, C., Pigulski, A., Wade, G. A., Weiss, W., Buysschaert, B., Ramiaramanantsoa, T., Bratcher, A. D., Gerhartz, C. J., Greco, J. J., Hardegree-Ullman, K., Lembryk, L., Oswald, W. L.
• Format: Article
• Language: English
• Subjects: Astrophysics; Physics; Sciences of the Universe
• ISSN: 0035-8711; 1365-2966
• DOI: 10.1093/mnras/stx207

Abstract ι Ori is a well-studied massive binary consisting of an O9 III + B1 III/IV star. Due to its high eccentricity (e = 0.764) and short orbital period (Porb = 29.133 76 d), it has been considered to be a good candidate to show evidence of tidal effects; however, none have previously been identified. Using photometry from the BRIght Target Explorer (BRITE)-Constellation space photometry mission, we have confirmed the existence of tidal distortions through the presence of a heartbeat signal at periastron. We combine spectroscopic and light-curve analyses to measure the masses and radii of the components, revealing ι Ori to be the most massive heartbeat system known to date. In addition, using a thorough frequency analysis, we also report the unprecedented discovery of multiple tidally induced oscillations in an O star. The amplitudes of the pulsations allow us to empirically estimate the tidal circularization rate, yielding an effective tidal quality factor Q ∼ 4 × 104.