We report the discovery and analysis of a massive, compact, hierarchical triple system (TIC 470710327) initially identified by citizen scientists in data obtained by NASA's Transiting Exoplanet Survey Satellite (TESS). Spectroscopic follow-up observations obtained with the HERMES spectrograph, combined with eclipse timing variations (ETVs), confirm that the system is comprised of three OB stars, with a compact 1.10 d eclipsing binary and a non-eclipsing tertiary on a 52.04 d orbit. Dynamical modelling of the system (from radial velocity and ETVs) reveal a rare configuration wherein the tertiary star (O9.5-B0.5V; 14-17 M⊙) is more massive than the combined mass of the inner binary (10.9-13.2 M⊙). Given the high mass of the tertiary, we predict that this system will undergo multiple phases of mass transfer in the future, and likely end up as a double neutron star gravitational wave progenitor or an exotic Thorne-Zytkow object. Further observational characterisation of this system promises constraints on both formation scenarios of massive stars as well as their exotic evolutionary end-products.
@article{arxiv.2202.06964,
title = {Planet Hunters TESS IV: A massive, compact hierarchical triple star system TIC 470710327},
author = {Nora L. Eisner and Cole Johnston and Silvia Toonen and Abigail J. Frost and Soetkin Janssens and Chris J. Lintott and Suzanne Aigrain and Hugues Sana and Michael Abdul-Masih and Karla Z. Arellano-Córdova and Paul G. Beck and Emma Bordier and Emily Canon and Ana Escorza and Mattias Fabry and Lars Hermansson and Steve Howell and Grant Miller and Shreeya Sheyte and Safaa Alhassan and Elisabeth M. L. Baeten and Frank Barnet and Stewart. J. Bean and Mikael Bernau and David M. Bundy and Marco Z. Di Fraia and Francis M. Emralino and Brian L. Goodwin and Pete Hermes and Tony Hoffman and Marc Huten and Roman Janíček and Sam Lee and Michele T. Mazzucato and David J. Rogers and Michael P. Rout and Johann Sejpka and Christopher Tanner and Ivan A. Terentev and David Urvoy},
journal= {arXiv preprint arXiv:2202.06964},
year = {2022}
}
Comments
Accepted for publication in MNRAS (11 pages, 8 figures)