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arXiv · 2509.06729

HD 143811 AB b: A Directly Imaged Planet Orbiting a Spectroscopic Binary in Sco-Cen

Nathalie K. Jones·Jason J. Wang·Eric L. Nielsen·Robert J. De Rosa·Anne E. Peck·William Roberson·Jean-Baptiste Ruffio·Jerry W. Xuan·Bruce A. Macintosh·S. Mark Ammons·Vanessa P. Bailey·Travis S. Barman·Joanna Bulger·Eugene Chiang·Jeffrey K. Chilcote·Gaspard Duchêne·Thomas M. Esposito·Michael P. Fitzgerald·Katherine B. Follette·Stephen Goodsell·James R. Graham·Alexandra Z. Greenbaum·Pascale Hibon·Patrick Ingraham·Paul Kalas·Quinn M. Konopacky·Michael C. Liu·Franck Marchis·Jérôme Maire·Christian Marois·Brenda Matthews·Dimitri Mawet·Stanimir Metchev·Maxwell A. Millar-Blanchaer·Rebecca Oppenheimer·David W. Palmer·Jenny Patience·Marshall D. Perrin·Lisa Poyneer·Laurent Pueyo·Abhijith Rajan·Julian Rameau·Fredrik T. Rantakyrö·Bin Ren·Aniket Sanghi·Dmitry Savransky·Adam C. Schneider·Anand Sivaramakrishnan·Adam J. R. W. Smith·Inseok Song·Remi Sommer·Sandrine Thomas·Kimberly Ward-Duong·Schuyler G. Wolff
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Abstract

We present confirmation of HD 143811 AB b, a substellar companion to spectroscopic binary HD 143811 AB through direct imaging with the Gemini Planet Imager (GPI) and Keck NIRC2. HD 143811 AB was observed as a part of the Gemini Planet Imager Exoplanet Survey (GPIES) in 2016 and 2019 and is a member of the Sco-Cen star formation region. The exoplanet is detected $\sim 430$ mas from the host star by GPI. With two GPI epochs and one from Keck/NIRC2 in 2022, we confirm through common proper motion analysis that the object is bound to its host star. We derive an orbit with a semi-major axis of $64 ^{+32}_{-14}$ au and eccentricity ${0.23 ^{+0.24}_{-0.16}}$. Spectral analysis of the GPI $H$-band spectrum and NIRC2 \textit{L'} photometry provides additional proof that this object is a substellar companion. We compare the spectrum of HD 143811 AB b to PHOENIX stellar models and Exo-REM exoplanet atmosphere models and find that Exo-REM models provide the best fits to the data. From the Exo-REM models, we derive an effective temperature of $1042^{+178}_{-132}$ K for the planet and translate the derived luminosity of the planet to a mass of $5.6 \pm 1.1~M_\textrm{Jup}$ assuming hot-start evolutionary models. HD 143811 AB b is the first directly imaged planet around a binary that is not on an ultra-wide orbit. Future characterization of this object will shed light on the formation of planets around binary star systems.

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Nathalie K. Jones, Jason J. Wang, Eric L. Nielsen, Robert J. De Rosa, Anne E. Peck, William Roberson, Jean-Baptiste Ruffio, Jerry W. Xuan, Bruce A. Macintosh, S. Mark Ammons, Vanessa P. Bailey, Travis S. Barman, Joanna Bulger, Eugene Chiang, Jeffrey K. Chilcote, Gaspard Duchêne, Thomas M. Esposito, Michael P. Fitzgerald, Katherine B. Follette, Stephen Goodsell, James R. Graham, Alexandra Z. Greenbaum, Pascale Hibon, Patrick Ingraham, Paul Kalas, Quinn M. Konopacky, Michael C. Liu, Franck Marchis, Jérôme Maire, Christian Marois, Brenda Matthews, Dimitri Mawet, Stanimir Metchev, Maxwell A. Millar-Blanchaer, Rebecca Oppenheimer, David W. Palmer, Jenny Patience, Marshall D. Perrin, Lisa Poyneer, Laurent Pueyo, Abhijith Rajan, Julian Rameau, Fredrik T. Rantakyrö, Bin Ren, Aniket Sanghi, Dmitry Savransky, Adam C. Schneider, Anand Sivaramakrishnan, Adam J. R. W. Smith, Inseok Song, Remi Sommer, Sandrine Thomas, Kimberly Ward-Duong, Schuyler G. Wolff. 2025-12-12. HD 143811 AB b: A Directly Imaged Planet Orbiting a Spectroscopic Binary in Sco-Cen. https://doi.org/10.3847/2041-8213%2Fae2007

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