Exoplanets & Exomoons

The First Circumbinary Planet Discovered With Radial Velocities

By Keith Cowing
Status Report
February 26, 2023
Filed under , , , , , , , , ,
The First Circumbinary Planet Discovered With Radial Velocities
Overview of the TOI-1338/BEBOP-1 system along with the extent of the systems habitable zone calculated using the Multiple Star HZ website (45). The conservative habitable zone is shown by the dark green region, while the optimistic habitable zone is shown by the light green region. Binary stars are marked by the blue stars in the centre. TOI-1338/BEBOP-1c’s orbit is shown by the red orbit models, based on 500 randomly drawn posterior samples from a kima run, shaded from the 50th to 99th percentiles. TOI-1338/BEBOP-1b’s orbit is shown by the yellow models, and is also based on 500 random samples drawn from the posterior in its discovery paper (17). — astro-ph.EP

We report the detection of a gas-giant planet in orbit around both stars of an eclipsing binary star system that also contains the smaller, inner transiting planet TOI-1338b.

The new planet, called TOI-1338/BEBOP-1c, was discovered using radial-velocity data collected with the HARPS and ESPRESSO spectrographs. Our analysis reveals it is a 65.2 M⊕ circumbinary planet with a period of 215.5 days.

This is the first detection of a circumbinary planet using radial-velocity observations alone, and makes TOI-1338/BEBOP-1 only the second confirmed multiplanet circumbinary system to date. We do not detect the smaller inner transiting planet with radial-velocity data, and can place an upper limit on the inner planet’s mass at 21.8 M⊕ with 99% confidence.

The inner planet is the first circumbinary planet amenable for atmospheric characterisation, using the James Webb Space Telescope.

Matthew R. Standing, Lalitha Sairam, David V. Martin, Amaury H. M. J. Triaud, Alexandre C. M. Correia, Gavin A. L. Coleman, Thomas A. Baycroft, Vedad Kunovac, Isabelle Boisse, Andrew Collier Cameron, Georgina Dransfield, João P. Faria, Michaël Gillon, Nathan C. Hara, Coel Hellier, Jonathan Howard, Ellie Lane, Rosemary Mardling, Pierre F. L. Maxted, Nicola J. Miller, Richard P. Nelson, Jerome A. Orosz, Franscesco Pepe, Alexandre Santerne, Daniel Sebastian, Stéphane Udry, William F. Welsh

Comments: Accepted for publication with Nature Astronomy. Main: 14-pages, 4-Figures, 1-table. Supporting material: 48-pages, 12-figures, 4-tables
Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Instrumentation and Methods for Astrophysics (astro-ph.IM); Solar and Stellar Astrophysics (astro-ph.SR)
Cite as: arXiv:2301.10794 [astro-ph.EP] (or arXiv:2301.10794v1 [astro-ph.EP] for this version)
Submission history
From: Matthew Standing
[v1] Wed, 25 Jan 2023 19:21:24 UTC (7,330 KB)

Explorers Club Fellow, ex-NASA Space Station Payload manager/space biologist, Away Teams, Journalist, Lapsed climber, Synaesthete, Na’Vi-Jedi-Freman-Buddhist-mix, ASL, Devon Island and Everest Base Camp veteran, (he/him) 🖖🏻