Direct Imaging Discovery of Giant Exoplanet β Pictoris d: A Decade-long Game of Hide-and-seek

2026/06/22 by Ben J. Sutlieff, Markus J. Bonse, Valentin Christiaens +94 · 4 voices
Physics and Astronomy · #Stellar, planetary, and galactic studies #Astronomy and Astrophysical Research #Adaptive optics and wavefront sensing

paper · pdf · doi:10.3847/2041-8213/ae80a0

Abstract

Abstract We report the direct imaging discovery of a third exoplanet in the β Pictoris ( β Pic) system. We detect β Pictoris d ( β Pic d) in noncoronagraphic observations obtained with the Very Large Telescope (VLT) Enhanced Resolution Imager and Spectrograph (ERIS), as well as multi-epoch archival datasets from the JWST Near Infrared Camera (NIRCam) and VLT/SPHERE. Astrometric measurements over an 11 yr baseline demonstrate that it is consistent with a gravitationally bound source with orbital motion. Joint multi-planet orbit fits of all three planets in the system yield a semimajor axis of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mn>26</mml:mn> <mml:mo>.</mml:mo> <mml:msubsup> <mml:mrow> <mml:mn>0</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>6.1</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>2.2</mml:mn> </mml:mrow> </mml:msubsup> </mml:math> au and inclination <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mn>89</mml:mn> <mml:mo>.</mml:mo> <mml:msubsup> <mml:mrow> <mml:mn>0</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>0.6</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>0.7</mml:mn> </mml:mrow> </mml:msubsup> </mml:math> deg for planet d. β Pic d has a larger orbital semimajor axis than the other known planets in the system, but is coplanar with the inner two planets, and its orbit is consistent with sculpting the inner edge of the debris disk. β Pic d has a contrast of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi mathvariant="normal">Δ</mml:mi> <mml:mi>L</mml:mi> <mml:mo accent="false">′</mml:mo> <mml:mo>=</mml:mo> <mml:mn>12.11</mml:mn> <mml:mo>±</mml:mo> <mml:mn>0.15</mml:mn> </mml:math> mag, with colors and luminosity that closely match those of 51 Eri b, another exoplanet in the β Pic moving group. Its VLT/ERIS and JWST/NIRCam colors are distinct from those of free-floating planetary-mass objects of a similar age and temperature. Its red F410M − F444W color indicates strong CO 2 absorption in its atmosphere and suggests significant enhancement in metals compared to free-floating objects. From the ATMO hot-start evolutionary models, we estimate an effective temperature of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mn>60</mml:mn> <mml:msubsup> <mml:mrow> <mml:mn>0</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>60</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>45</mml:mn> </mml:mrow> </mml:msubsup> </mml:math> K and mass of 2.4 ± 0.6 M Jup , which also closely matches similar estimates for 51 Eri b. β Pic d is among the lowest-mass exoplanets imaged from the ground. This discovery highlights the deep sensitivity achievable with ground-based imaging in the mid-infrared and the discovery potential of future high-contrast observations with the Extremely Large Telescope.

Citations

• Cold and eccentric: a high-spectral resolution view of 51 Eri b with VLT/HiRISE
• Jupiter-like uniform metal enrichment in a system of multiple giant exoplanets
• The SPHEREx Satellite Mission
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• Evidence for a sub-jovian planet in the young TWA7 disk
• Dynamics of the β Pictoris planetary system and possibility of an additional planet
• Into the red: an M-band study of the chemistry and rotation of β Pictoris b at high spectral resolution
• Performance of NIRCam on JWST in Flight
• The JWST Early Release Science Program for Direct Observations of Exoplanetary Systems I: High-contrast Imaging of the Exoplanet HIP 65426 b from 2 to 16 μm
• On the masses, age, and architecture of the VHS J1256−1257AB b system
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• The Astropy Project: Building an Open-science Project and Status of the v2.0 Core Package*
• emcee : The MCMC Hammer
• The James Webb Space Telescope
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Discussions

• Whoa! Simultaneous papers announcing the discovery of a new directly imaged planet - beta Pictoris d!!! arxiv.org/pdf/2606.23801 arxiv.org/pdf/2606.23789 It's just so BIG. I can't believe it's just so [bsky, 262 points, 9 comments]
• A third giant planet for beta Pictoris! arxiv.org/pdf/2606.23801 arxiv.org/abs/2606.23789 It was fun to have an early first look at this result as a reviewer. Excellent papers. [bsky, 5 points, 0 comments]
• Congratulations to Dr Ben Sutlieff (@bensutlieff.bsky.social), Luke Parker (@luke-parker.bsky.social), Prof. Jayne Birkby (@jaynebirkby.bsky.social), and Leyla Iskandarli on the discovery of beta Pic [bsky, 5 points, 0 comments]
• Direct Imaging Discovery of Giant Exoplanet β Pictoris d - A Decade-Long Game of Hide-and-Seek / Discovery of an Exterior Third Planet Orbiting Pictoris: arxiv.org/abs/2606.23801 / arxiv.org/abs/2606. [bsky, 2 points, 0 comments]

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