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.

We present simultaneous 0.65–2.5 μm medium resolution (3300 ≤ Rλ ≤ 8100) VLT/X-shooter spectra of the relatively young (150–300 Myr) low-mass (19 ± 5MJup) L–T transition object VHS 1256−1257 b, a known spectroscopic analog of HR8799d. The companion is a prime target for the JWST Early Release Science (ERS) and one of the highest-amplitude variable brown dwarfs known to date. We compare the spectrum to the custom grids of cloudless ATMO models, exploring the atmospheric composition with the Bayesian inference tool ForMoSA. We also reanalyze low-resolution HST/WFC3 1.10–1.67 μm spectra at minimum and maximum variability to contextualize the X-shooter data interpretation. The models reproduce the slope and most molecular absorption from 1.10 to 2.48 μm self-consistently, but they fail to provide a radius and a surface gravity consistent with evolutionary model predictions. They do not reproduce the optical spectrum and the depth of the K I doublets in the J band consistently. We derived Teff = 1380±54 K, log(g) = 3.97±0.48 dex, [M/H] = 0.21±0.29, and C/O > 0.63. Our inversion of the HST/WFC3 spectra suggests a relative change of $ 27^{+6}_{-5} $ K of the disk-integrated Teff correlated with the near-infrared brightness. Our data anchor the characterization of that object in the near-infrared and could be used jointly to the ERS mid-infrared data to provide the most detailed characterization of an ultracool dwarf to date.

Accretion signatures from bound brown dwarf and protoplanetary companions provide evidence for ongoing planet formation, and accreting substellar objects have enabled new avenues to study the astrophysical mechanisms controlling the formation and accretion processes. Delorme 1 (AB)b, a ∼30–45 Myr circumbinary planetary-mass companion, was recently discovered to exhibit strong Hα emission. This suggests ongoing accretion from a circumplanetary disk, somewhat surprising given canonical gas disk dispersal timescales of 5–10 Myr. Here, we present the first NIR detection of accretion from the companion in Paβ, Paγ, and Brγ emission lines from SOAR/TripleSpec 4.1, confirming and further informing its accreting nature. The companion shows strong line emission, with L line ≈ 1–6 × 10−8 L ⊙ across lines and epochs, while the binary host system shows no NIR hydrogen line emission (L line < 0.32–11 × 10−7 L ⊙). Observed NIR hydrogen line ratios are more consistent with a planetary accretion shock than with local line excitation models commonly used to interpret stellar magnetospheric accretion. Using planetary accretion shock models, we derive mass accretion rate estimates of M ̇ pla ∼ 3 –4 × 10−8 M J yr−1, somewhat higher than expected under the standard star formation paradigm. Delorme 1 (AB)b’s high accretion rate is perhaps more consistent with formation via disk fragmentation. Delorme 1 (AB)b is the first protoplanet candidate with clear (signal-to-noise ratio ∼5) NIR hydrogen line emission.

No abstract

Aims. We aim to revisit the formation pathway of AB Pic b, one of the first companions ever imaged straddling the exoplanet/browndwarf boundary. We based this study on a rich set of observations which allows us to investigate its orbital and atmospheric properties. Methods. We composed a spectrum of AB Pic b merging archival medium-resolution (R ∼ 4000) VLT/SINFONI K-band (1.96 -2.45 µm) data, with published spectra at J and H-bands from SINFONI, at Lp-band from Magellan-AO/CLIO2, and photometric measurements from HST (visible) and Spitzer (mid-infrared). We modeled the spectrum implementing ForMoSA, following a forwardmodeling approach based on two atmospheric models: ExoREM and BT-SETTL13. In parallel, we determined the orbital properties of AB Pic b fitting orbital solutions to astrometric measurements from NaCo (2003) and SPHERE (2015. Results. The orbital solutions favor a semi-major axis of 190 +200 −50 au on a highly-inclined orbit (edge-on), but with a poorly constrained eccentricity. From the atmospheric modeling with Exo-REM, we derive an effective temperature of 1700 ± 50 K and surface gravity of 4.5 ± 0.3 dex, consistent with previous works, and we report for the first time a C / O ratio of 0.58 ± 0.08, consistent with the Sun's value. The posteriors are sensitive to the wavelength interval and the family of models used. Given the published rotation period of 2.1 hr and our derived vsin(i) of 73 +11 −27 km/s, we estimate for the first time the true obliquity of AB Pic b to be between 45 and 135 deg, indicating a rather significant misalignment between the planet's spin and orbit orientations. Finally, the existence of a proper motion anomaly between the Hipparcos and Gaia Early Data Release 3 compared to our SPHERE detection limits and adapted radial velocity limits indicate the potential existence of a ∼6 M Jup inner planet orbiting from 2 to 10 au (40 to 200 mas). Conclusions. The possible existence of an inner companion, together with the likely miss-alignment of the spin axis orientation, strongly favor a formation path by gravitational instability or core accretion within a disk closer inside followed by a dynamical interaction which scattered AB Pic b to its current location. Confirmation and characterization of this unseen inner exoplanet and access to a broader wavelength coverage for the characterization of AB Pic b will be essential to probe the uncertainties associated with the atmospheric and orbital parameters.