Exoplanet detections have revolutionized astronomy, offering new insights into solar system architecture and planet demographics. While nearly 1900 exoplanets have now been discovered and confirmed, 1 none are still in the process of formation. Transition discs, protoplanetary disks with inner clearings 2-4 best explained by the influence of accreting planets 5 , are natural laboratories for the study of planet formation. Some transition discs show evidence for the presence of young planets in the form of disc asymmetries 6, 7 or infrared sources detected within their clearings, as in the case of LkCa 15. 8,9 Attempts to observe directly sig-Author Contributions: This work merged two independently acquired and analysed data sets. S.S. led preparation of the manuscript, the orbital fits, and the acquisition and analysis of the LBT data while K.B.F. led the acquisition and analysis of the MagAO data, development of the MagAO SDI pipeline, and drafted MagAO manuscript sections.

We present the highest fidelity spectrum to date of a planetary-mass object. VHS 1256 b is a <20 M Jup widely separated (∼8″, a = 150 au), young, planetary-mass companion that shares photometric colors and spectroscopic features with the directly imaged exoplanets HR 8799c, d, and e. As an L-to-T transition object, VHS 1256 b exists along the region of the color–magnitude diagram where substellar atmospheres transition from cloudy to clear. We observed VHS 1256 b with JWST's NIRSpec IFU and MIRI MRS modes for coverage from 1 to 20 μm at resolutions of ∼1000–3700. Water, methane, carbon monoxide, carbon dioxide, sodium, and potassium are observed in several portions of the JWST spectrum based on comparisons from template brown dwarf spectra, molecular opacities, and atmospheric models. The spectral shape of VHS 1256 b is influenced by disequilibrium chemistry and clouds. We directly detect silicate clouds, the first such detection reported for a planetary-mass companion.

We present JWST Early Release Science coronagraphic observations of the super-Jupiter exoplanet, HIP 65426b, with the Near-Infrared Camera (NIRCam) from 2 to 5 μm, and with the Mid-Infrared Instrument (MIRI) from 11 to 16 μm. At a separation of ∼0.″82 (87 − 31 + 108 au), HIP 65426b is clearly detected in all seven of our observational filters, representing the first images of an exoplanet to be obtained by JWST, and the first-ever direct detection of an exoplanet beyond 5 μm. These observations demonstrate that JWST is exceeding its nominal predicted performance by up to a factor of 10, depending on separation and subtraction method, with measured 5σ contrast limits of ∼1 × 10−5 and ∼2 × 10−4 at 1″ for NIRCam at 4.4 μm and MIRI at 11.3 μm, respectively. These contrast limits provide sensitivity to sub-Jupiter companions with masses as low as 0.3M Jup beyond separations of ∼100 au. Together with existing ground-based near-infrared data, the JWST photometry are fit well by a BT-SETTL atmospheric model from 1 to 16 μm, and they span ∼97% of HIP 65426b's luminous range. Independent of the choice of model atmosphere, we measure an empirical bolometric luminosity that is tightly constrained between log L bol / L ⊙ = −4.31 and −4.14, which in turn provides a robust mass constraint of 7.1 ± 1.2 M Jup. In totality, these observations confirm that JWST presents a powerful and exciting opportunity to characterize the population of exoplanets amenable to high-contrast imaging in greater detail.

Protoplanetary disks with large inner dust cavities are thought to host massive planetary or substellar companions. These disks show asymmetries and rings in the millimeter continuum caused by dust trapping in pressure bumps and potentially vortices or horseshoes. The origin of the asymmetries and their diversity remains unclear. We present a comprehensive study of 16 disks for which the gas surface density profile has been constrained by CO isotopologue data. First, we compare the azimuthal extents of the dust continuum profiles with the local gas surface density in each disk and find that the asymmetries correspond to higher Stokes numbers or low gas surface density. We discuss which asymmetric structures can be explained by a horseshoe, a vortex, or spiral density waves. Second, we reassess the gas gap radii from the 13CO maps, which are about a factor of 2 smaller than the dust ring radii, suggesting that the companions in these disks are in the brown dwarf (∼15–50 M Jup) or super-Jovian (∼3–15 M Jup) mass regime on eccentric orbits. This is consistent with the estimates from contrast curves on companion mass limits. These curves rule out (sub)stellar companions (q > 0.05) for the majority of the sample at the gap location, but it remains possible at even smaller radii. Third, we find that spiral arms in scattered-light images are primarily detected around high-luminosity stars with disks with wide gaps, which can be understood by the dependence of the spiral arm pitch angle on disk temperature and companion mass.

We present multi-epoch non-redundant masking observations of the T Cha transition disk, taken at the VLT and Magellan in H, Ks, and L bands. T Cha is one of a small number of transition disks that host companion candidates discovered by high-resolution imaging techniques, with a putative companion at a position angle of 78 • , separation of 62 mas, and contrast of ∆L = 5.1 mag. We find comparable binary parameters in our re-reduction of the initial detection images, and similar parameters in the 2011 L , 2013 NaCo L , and 2013 NaCo Ks data sets. We find a close-in companion signal in the 2012 NaCo L dataset that cannot be explained by orbital motion, and a non-detection in the 2013 MagAO/Clio2 L data. However, Monte-carlo simulations show that the best fits to the 2012 NaCo and 2013 MagAO/Clio2 followup data may be consistent with noise. There is also a significant probability of false non-detections in both of these data sets. We discuss physical scenarios that could cause the best fits, and argue that previous companion and scattering explanations are inconsistent with the results of the much larger dataset presented here.