The JWST Early Release Science Program for Direct Observations of Exoplanetary Systems I: High Contrast Imaging of the Exoplanet HIP 65426 b from 2-16 μ m

We present JWST Early Release Science (ERS) coronagraphic observations of the super-Jupiter exoplanet, HIP 65426 b, with the Near-Infrared Camera (NIRCam) from 2−5 µm, and with the MidInfrared Instrument (MIRI) from 11−16 µm. At a separation of ∼0.8200 (87+108 −31 au), HIP 65426 b 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, with measured 5σ contrast limits of ∼4×10−6 (∼2.4 µJy) and ∼2×10−4 (∼10 µJy) at 100 for NIRCam at 3.6 µm and MIRI at 11.3 µm, respectively. These contrast limits provide sensitivity to sub-Jupiter companions with masses as low as 0.3MJup beyond separations of ∼100 au. Together with existing ground-based near-infrared data, the JWST photometry are well fit by a BT-SETTL atmospheric model from 1−16 µm, and span ∼97% of HIP 65426 b’s luminous range. Independent of the choice of forward model atmosphere we measure an empirical bolometric luminosity that is tightly constrained between log(Lbol/L)=−4.35 to −4.21, which in turn provides a robust mass constraint of 7.1±1.1 MJup. In totality, these observations confirm that JWST presents a powerful and exciting opportunity to characterise the population of exoplanets amenable to direct imaging in greater detail.
arXiv