Direct Imaging Discovery of Giant Exoplanet $\beta$ Pictoris d: A Decade-Long Game of Hide-and-Seek

Abstract

We report the direct imaging discovery of a third exoplanet in the $\beta$ Pictoris system. We detect $\beta$ Pictoris d ($\beta$ Pic d) in non-coronagraphic observations obtained with VLT/ERIS as well as multi-epoch archival datasets from JWST/NIRCam and VLT/SPHERE. Astrometric measurements over an 11-year 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 semi-major axis of $26.0_{-6.1}^{+2.2}$ au and inclination $89.0_{-0.6}^{+0.7}$ deg for planet d. $\beta$ Pic d has a larger orbital semi-major 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. $\beta$ Pic d has a contrast of $\Delta L^{\prime }=12.11\pm 0.15$ mag, with colors and luminosity that closely match those of 51 Eri b, another exoplanet in the $\beta$ Pictoris 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 $600_{-60}^{+45}$ K and mass of $2.4\pm 0.6$ $M_{\mathrm{Jup}}$, which also closely matches similar estimates for 51 Eri b. $\beta$ 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.

27 pages, 8 figures, accepted for publication in ApJ Letters; very minor changes to match journal version, references updated. Press embargo to be lifted on Wednesday 15th July 2026 at 14:00 CEST

References in corpus (82)

• Array Programming with NumPy
• The Gaia mission
• The Astropy Project: Sustaining and Growing a Community-oriented Open-source Project and the Latest Major Release (v5.0) of the Core Package
• Gaia Data Release 3: Summary of the content and survey properties
• The James Webb Space Telescope
• Direct Imaging of Multiple Planets Orbiting the Star HR 8799
• astroquery: An Astronomical Web-Querying Package in Python
• On the Luminosity of Young Jupiters
• The James Webb Space Telescope Mission
• The Gemini Planet Imager Exoplanet Survey: Giant Planet and Brown Dwarf Demographics From 10-100 AU
• Two accreting protoplanets around the young star PDS 70
• NIRCam Performance on JWST In Flight
• Fundamental limitations of high contrast imaging set by small sample statistics
• A new set of atmosphere and evolution models for cool T-Y brown dwarfs and giant exoplanets
• The Hipparcos-Gaia Catalog of Accelerations: Gaia EDR3 Edition
• Molecular Gas Clumps from the Destruction of Icy Bodies in the $\beta$ Pictoris Debris Disk
• VIP: Vortex Image Processing package for high-contrast direct imaging
• HST/ACS Multiband Coronagraphic Imaging of the Debris Disk around Beta Pictoris
• The JWST Early Release Science Program for Direct Observations of Exoplanetary Systems II: A 1 to 20 Micron Spectrum of the Planetary-Mass Companion VHS 1256-1257 b
• The Field Substellar Mass Function Based on the Full-sky 20-pc Census of 525 L, T, and Y Dwarfs
• orbitize!: A Comprehensive Orbit-fitting Software Package for the High-contrast Imaging Community
• Peering into the formation history of beta Pictoris b with VLTI/GRAVITY long baseline interferometry
• Characterizing 51 Eri b from 1-5 $\mu$m: a partly-cloudy exoplanet
• Direct confirmation of the radial-velocity planet $\beta$ Pic c
• orvara: An Efficient Code to Fit Orbits using Radial Velocity, Absolute, and/or Relative Astrometry
• The Sonora Substellar Atmosphere Models. IV. Elf Owl: Atmospheric Mixing and Chemical Disequilibrium with Varying Metallicity and C/O Ratios
• Discovery of a low-mass companion inside the debris ring surrounding the F5V star HD206893
• The Orbit and Transit Prospects for $\beta$ Pictoris b constrained with One Milliarcsecond Astrometry
• Dynamical evolution of an eccentric planet and a less massive debris disc
• The mass of Beta Pictoris c from Beta Pictoris b orbital motion
• Planetesimal driven migration as an explanation for observations of high levels of warm, exozodiacal dust
• SPHERE IRDIS and IFS astrometric strategy and calibration
• VLT/SPHERE robust astrometry of the HR8799 planets at milliarcsecond-level accuracy Orbital architecture analysis with PyAstrOFit
• Direct discovery of the inner exoplanet in the HD206893 system. Evidence for deuterium burning in a planetary-mass companion
• AF Lep b: the lowest mass planet detected coupling astrometric and direct imaging data
• Two Directly Imaged, Wide-orbit Giant Planets around the Young, Solar Analog TYC 8998-760-1
• Direct imaging discovery of a super-Jovian around the young Sun-like star AF Leporis
• Direct Imaging and Astrometric Detection of a Gas Giant Planet Orbiting an Accelerating Star
• Astrometric Accelerations as Dynamical Beacons: A Giant Planet Imaged Inside the Debris Disk of the Young Star AF Lep
• Precise Dynamical Masses and Orbital Fits for $\beta$ Pic b and $\beta$ Pic c
• A temperate super-Jupiter imaged with JWST in the mid-infrared
• Separating extended disc features from the protoplanet in PDS 70 using VLT/SINFONI
• Planet populations inferred from debris discs: insights from 178 debris systems in the ISPY, LEECH and LIStEN planet-hunting surveys
• Four-of-a-kind? Comprehensive atmospheric characterisation of the HR 8799 planets with VLTI/GRAVITY
• Spectral and orbital characterisation of the directly imaged giant planet HIP 65426 b
• The Gemini Planet Imager Exoplanet Survey: Dynamical Mass of the Exoplanet beta Pictoris b from Combined Direct Imaging and Astrometry
• The Gemini NICI Planet-Finding Campaign: The Orbit of the Young Exoplanet beta Pictoris b
• Exocomets size distribution in the $\beta$ Pictoris planetary system
• The Hawaii Infrared Parallax Program. V. New T-Dwarf Members and Candidate Members of Nearby Young Moving Groups
• On the Masses, Age, and Architecture of the VHS J1256-1257AB b System
• The Enhanced Resolution Imager and Spectrograph for the VLT
• Retrieval study of cool, directly imaged exoplanet 51 Eri b
• WIde Separation Planets In Time (WISPIT): A Gap-clearing Planet in a Multi-ringed Disk around the Young Solar-type Star WISPIT 2
• The SPHEREx Satellite Mission
• Revisiting the atmosphere of the exoplanet 51 Eridani b with VLT/SPHERE
• Limits on the Mass and Initial Entropy of 51 Eri b from Gaia EDR3 Astrometry
• The vector-apodizing phase plate coronagraph: design, current performance, and future development
• Octofitter: Fast, Flexible, and Accurate Orbit Modelling to Detect Exoplanets
• JWST-TST High Contrast: Living on the Wedge, or, NIRCam Bar Coronagraphy Reveals CO${}_2$ in the HR 8799 and 51 Eri Exoplanets' Atmospheres
• Evidence for SiO cloud nucleation in the rogue planet PSO J318
• Comparing Apples with Apples: Robust Detection Limits for Exoplanet High-Contrast Imaging in the Presence of non-Gaussian Noise
• The ALMA survey to Resolve exoKuiper belt Substructures (ARKS) II. The radial structure of debris discs
• JWST-TST High Contrast: JWST/NIRCam observations of the young giant planet $\beta$ Pic b
• Has the dust clump in the debris disk of Beta Pictoris moved?
• The $\beta$ Pictoris b Hill sphere transit campaign. Paper I: Photometric limits to dust and rings
• The beta Pictoris system: Setting constraints on the planet and the disk structures at mid-IR wavelengths with NEAR
• The compositions of the HR 8799 planets reflect accretion of both solids and metal-enriched gas
• Jupiter-like uniform metal enrichment in a system of multiple giant exoplanets
• Multi-modal atmospheric characterization of $\beta$ Pictoris b: Adding high-resolution continuum spectra from GRAVITY
• The ALMA survey to Resolve exoKuiper belt Substructures (ARKS): VI. Asymmetries and offsets
• Dynamical Mass Estimates of the $\beta$ Pictoris Planetary System Through Gaussian Process Stellar Activity Modelling
• Use the 4S (Signal-Safe Speckle Subtraction): Explainable Machine Learning reveals the Giant Exoplanet AF Lep b in High-Contrast Imaging Data from 2011
• Direct Spectroscopy of 51 Eridani b with JWST NIRSpec
• Formation of the warped debris disc around $\beta$ Pictoris
• Spectroscopic Transit Search: a self-calibrating method for detecting planets around bright stars
• The ExoGRAVITY survey: A K-band spectral library of giant exoplanet and brown dwarf companions
• Dynamics of the Beta Pictoris planetary system and possibility of an additional planet
• WIde Separation Planets In Time (WISPIT): Two directly imaged exoplanets around the Sun-like stellar binary WISPIT 1
• The mid-infrared spectrum of $\beta$ Pictoris b. First VLTI/MATISSE interferometric observations of an exoplanet
• Image quality and high contrast improvements on VLT/NACO
• YSES 2b is a background star: Differential astrometric M-dwarf measurements in time
• Direct Images of CO2 Absorption in the Atmosphere of a Super-Jupiter: Enhanced Metallicity Suggestive of Formation in a Disk