# The Most Massive Heartbeat: An In-depth Analysis of {\iota} Orionis

## TL;DR

This paper confirms tidal distortions in { extiota} Ori through space photometry, measures the masses and radii of its components, and reports the first detection of tidally induced oscillations in an O star, establishing it as the most massive heartbeat system.

## Contribution

It provides the first confirmed heartbeat signal in { extiota} Ori, measures its stellar parameters, and discovers multiple tidally induced oscillations in an O star, advancing understanding of tidal interactions in massive binaries.

## Key findings

- Confirmed heartbeat signal at periastron in { extiota} Ori.
- Measured the masses and radii of the binary components.
- Discovered multiple tidally induced oscillations in an O star.

## Abstract

{\iota} 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 (P orb = 29.13376 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 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 {\iota} 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 $\approx 4 \times 10^{4}$ .