Ben J. Sutlieff

We present the discovery of RX J0534.0-0221 b, a giant planet orbiting an M dwarf star in the β Pictoris moving group. RX J0534 was originally observed with JWST/NIRCam in the F444W and F200W filters. Observations in F444W reveal a point source at signal-to-noise ratio ∼17.5 at ∼ 0 . ″ 41 (∼14 au) from the host star, with no detection of the source in F200W. A follow-up observation with LBTI/LMIRCam in the L ′ band redetects the source 16 months after the JWST epoch, providing evidence for common proper motion over a chance alignment with a background interloper at the 6 σ –7 σ level. Atmospheric grid model fits to the available photometry yield the bolometric luminosity log 10 ( L / L ⊙ ) = − 5.4 8 − 0.19 + 0.10 dex. At an age of 18–26 Myr, hot-start evolutionary models predict M = 2 . 8 − 0.5 + 0.5 M _Jup and T eff = 67 4 − 49 + 57 K. From the L ′ − F 444 W color and magnitudes, we find evidence for disequilibrium chemistry or enhanced metallicity in the planet's atmosphere. Additionally, an extended structure is detected in the JWST F200W observation, consistent with a resolved debris disk with a peak density radius of 7 9 − 3 + 3 au and an inclination of 56 . ° 5 − 1.5 + 1.5 RX J0534 b is one of the lowest-mass planets imaged to date. After TWA 7 b, it is the second imaged planet around an M dwarf orbiting at solar system scales (the first within 40 au) and the first to be confirmed via common proper motion. Future orbital monitoring and atmospheric characterization will shed light on its formation history, a particularly interesting question given the challenging nature of giant planet formation around M dwarfs.

We report the direct imaging detection of a stellar companion to HD 101452 (HIP 56925; Gaia DR3 5384905720847544192), an A star historically used as an infrared flux calibrator. The companion was identified from an asymmetry in the stellar point-spread function (PSF) using short-integration (μ m that was obtained as part of the absolute flux calibration program CAL 4496. We detect the stellar companion in four MIRI imaging filters at a projected separation of 1 . ″ 3 with a mid-infrared flux ratio of approximately 27×, warranting its removal from the ensemble of JWST flux calibrator systems. This detection also demonstrates that noncoronagraphic MIRI imaging can recover companions at separations below 3 λ / D when a reference star with a closely matched flux level to the science target is available. Using the measured contrast curves from the calibration data, we evaluate the predicted sensitivity achievable with similar short MIRI observations for nearby stars (<30 pc) that are of interest to the direct imaging community with comparable brightness to HD 101452 (W4 ∼ 6.8 mag). We find that integrations of only 17–42 s are capable of detecting sub-Jupiter-mass planets at solar system–like separations around a subset of neighboring systems if the PSF subtraction is conducted with closely flux-matched references. These results demonstrate that minutes-length, noncoronagraphic MIRI observations can provide a powerful and efficient new avenue for exploring the cold giant planet population around nearby stars.

We present JWST NIRCam observations of two M dwarf systems located in the TW Hydra association, TWA 10 and TWA 25. Both systems harbor detected debris disks in the F200W and F444W filters. Whereas the TWA 25 disk has been previously imaged, these observations represent the discovery and first images of the TWA 10 disk. In addition to planet searches within these systems, we also conduct an analysis of each debris disk, where the TWA 10 debris disk is characterized for the first time. We find that the TWA 10 debris disk is very large, with a radius of ∼191 au, significantly greater than other known M dwarf debris disks. The TWA 25 disk hosts a sharp inner dust surface density power law and a moderate brightness asymmetry present at 2 μ m, suggesting potential sculpting from inner planets and potentially enhanced collisional activity. Finally, we find one potential companion candidate within the TWA 10 system and two within the TWA 25 system, although the measured F200W − F444W color suggests that these candidates are likely background objects. Both systems do not have measured IR-excesses in their SEDs, where radiative-transfer modeling suggests that these disks (and potentially more M dwarf disks) were likely missed by previous disk detection surveys due to having low luminosity fractions.

We report the detection of photometric variability in the directly imaged super-Jupiter β Pictoris b ( β Pic b). Using JWST NIRCam dual-band coronagraphic imaging, we conducted a 16 hr continuous photometric monitoring campaign in the F210M and F410M filters. We developed and validated a time-series photometry framework that combines point-spread function subtraction, principal component analysis for systematic noise removal, and injection-and-recovery tests to confirm signal fidelity. Both light curves show consistent sinusoidal variability at ∼5 σ and ≫5 σ significance in the F210M and F410M bands, respectively. A joint sinusoidal fit yields a rotation period of P _rot = 9.00 ± 0.13 hr and variability amplitudes of 0.85% ± 0.07% and 0.89% ± 0.04% in F210M and F410M, respectively. The near-identical amplitudes and periods in both bands confirm a common astrophysical origin in a heterogeneous atmosphere. Combining P _rot with the previously measured projected rotational velocity, we constrain the line-of-sight spin axis inclination of β Pic b. The result favors an equator-on viewing geometry, consistent with line-of-sight spin–orbit alignment: the planetary spin axis, orbital plane, debris disk, and stellar equator are all mutually aligned. This stands in sharp contrast to the large obliquities of wide-separation companions that are likely formed via gravitational fragmentation. Together with the system’s young age, this observation provides independent dynamical evidence that β Pic b formed via core accretion. This result constitutes the first detection of rotational modulation in a close-in, high-contrast exoplanet that likely formed via core accretion, demonstrating that time-series coronagraphic imaging with JWST opens a powerful new window onto the rotation, atmospheric dynamics, and spin–orbit architecture of this population.

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 26 . 0 − 6.1 + 2.2 au and inclination 89 . 0 − 0.6 + 0.7 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 Δ L ′ = 12.11 ± 0.15 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 60 0 − 60 + 45 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.

VHS 1256 b was the first planetary-mass companion to be observed with the James Webb Space Telescope’s Mid-Infrared Instrument (JWST/MIRI) using the Medium-Resolution Spectrometer (MRS). The MRS provides high-quality integral-field spectral data in the mid-infrared (IR) wavelengths from 4.9–18 μ m. This data set serves as a testbed for applying cross-correlation techniques to characterize exoplanet atmospheres. We implement the so-called molecular mapping approach, which consists of performing a spectral cross-correlation between each spectral pixel and atmospheric model templates. We compare these results with those obtained from cross-correlation of the extracted spectrum. Using a self-consistent Exo-REM atmospheric model grid, we constrain the temperature, surface gravity, C/O ratio, and metallicity, finding values consistent with those obtained from other analysis methods. We detect CO (S/N ∼ 25) and H ₂ O (S/N ∼ 76), with tentative detections of NH ₃ and CH ₄ (S/N ∼ 3). We test cross-correlation to measure trace-species abundances and isotopic ratios. We measure a volume mixing ratio (VMR) of [ NH 3 ] = − 5.7 3 − 0.14 + 0.15 and an isotopic ratio 12 C / 13 C = 77 . 8 − 10 + 13 , both consistent with free-chemistry retrievals. The derived NH ₃ VMR, combined with the measured temperature and radius, is consistent with VHS 1256 b having a mass above the deuterium-burning limit. These results demonstrate the diagnostic power of mid-IR spectroscopy and highlight cross-correlation as a robust method for characterizing directly imaged exoplanets, even in future higher-contrast regimes where spectral extraction becomes challenging. Future MIRI MRS observations across a wider range of temperatures and masses will further expand our understanding of planetary atmospheric chemistry.

Aims . We describe the design, laboratory manufacture, and on-sky testing of the grating vector apodizing phase plate (gvAPP) coronagraph for the Enhanced Resolution Imager and Spectrograph (ERIS) on the Very Large Telescope. Methods . We used both laboratory measurements and on-sky observations to characterise the gvAPP in several different filters, from the K to the L band. Results . In testing, the gvAPP reaches its design specification in the transmission of the optic with 90% in the K bands and 60% in the L band. While the gvAPP reaches its designed raw contrast performance of 1 × 10 ⁻⁵ , it does not reach the post-processed contrast of 5 × 10 ⁻⁵ in on-sky observations. Electronic detector noise, due to the Airy core of the coronagraphic point spread function inducing cross-talk between the readout amplifiers, produces a repeated pattern within the coronagraphic regions of the gvAPP. Conclusions . Despite these limitations, we recommend the gvAPP as a tool for characterising substellar companions with known separations and position angles, which allow them to be placed in the coronagraphic dark holes for observations. The ERIS gvAPP’s leakage term can also be used as a photometric reference for time series observations; however, we caution that the contrast performance may limit such studies to only the brightest targets. ERIS gvAPP data quality may be improved further with better modelling of detector electronic noise. This work is a pathfinder for Extremely Large Telescope instruments including METIS, which will include gvAPP coronagraphs with improved designs based on these results.

We present a new analysis of the spectroscopic variability of WISE J104915.57−531906.1AB (WISE 1049AB, L7.5+T0.5), observed using the NIRSpec instrument on board the James Webb Space Telescope (GO 2965; PI: Biller). We explore the variability of the dominant molecular bands present in their 0.6–5.3 μ m spectra (H ₂ O, CH ₄ , and CO), finding that the B component exhibits a higher maximum deviation than the A component in all the wavelength ranges tested. The light curves reveal wavelength-dependent (atmospheric depth) and possibly chemistry-dependent variability. In particular, for the A component, the variability in the light curves at the wavelengths traced by the CH ₄ and CO molecular absorption features is higher than that for of H ₂ O, even when both trace similar pressure levels. We conclude that clouds alone are unlikely to explain the increased variability of CO and CH ₄ with respect to H ₂ O, suggesting that an additional physical mechanism is needed to explain the observed variability. This mechanism is probably due to thermochemical instabilities. Finally, we provide visual representations of the 3D atmospheric maps reconstructed for both components using the molecular band contributions at different pressure levels and the fits of planetary-scale waves.

We report the discovery of a debris disk surrounding the M3 star TWA 20, revealed by JWST coronagraphic observations using the Near Infrared Camera. With reference differential imaging (RDI), we resolve the disk in scattered light in the F200W filter at a high signal-to-noise ratio and in the F444W filter at a low signal-to-noise ratio. The disk morphology and orientation are characterized via a forward-modeling approach, where we determine a radius of 64.7 − 6.5 + 6.2 au and an inclination of 70.1 − 3.3 + 2.5 degrees. Utilizing our forward model, we improve the fidelity of the debris disk image using model-constrained RDI. The newly discovered disk is one of only six disks detected in scattered light that orbit M dwarf stars; it is the third largest of the six resolved M dwarf disks and orbits the third faintest host star. The detection of this disk exemplifies the sensitivity of JWST to debris disks around low-luminosity host stars, which have historically been difficult to detect because these disks are cool and dim. We identify a nebulous structure that cannot be explained by an axisymmetric disk. A search for companions in the TWA 20 system yields no candidates.

Large-amplitude variations are commonly observed in the atmospheres of directly imaged exoplanets and brown dwarfs. VHS 1256B, the most variable known planet-mass object, exhibits a near-infrared flux change of nearly 40%, with red color and silicate features revealed in recent JWST spectra, challenging current theories. Using a general circulation model, we demonstrate that VHS 1256B’s atmosphere is dominated by planetary-scale dust storms persisting for tens of days, with large patchy clouds propagating with equatorial waves. This weather pattern, distinct from the banded structures seen on solar system giants, simultaneously explains the observed spectra and critical features in the rotational light curves, including the large amplitude, irregular evolution, and wavelength dependence, as well as the variability trends observed in near-infrared color-magnitude diagrams of dusty substellar atmospheres.