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

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jats:titleAbstract</jats:title> jats:pWe present JWST Early Release Science coronagraphic observations of the super-Jupiter exoplanet, HIP 65426b, with the Near-Infrared Camera (NIRCam) from 2 to 5 jats:italicμ</jats:italic>m, and with the Mid-Infrared Instrument (MIRI) from 11 to 16 jats:italicμ</jats:italic>m. At a separation of ∼0.″82 (87jats:inline-formula jats:tex-math

</jats:tex-math> <mml:math xmlns:mml="" overflow="scroll"> mml:msubsup <mml:mrow /> mml:mrow mml:mo−</mml:mo> mml:mn31</mml:mn> </mml:mrow> mml:mrow mml:mo+</mml:mo> mml:mn108</mml:mn> </mml:mrow> </mml:msubsup> </mml:math> <jats:inline-graphic xmlns:xlink="" xlink:href="apjlacd93eieqn1.gif" xlink:type="simple" /> </jats:inline-formula> 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 jats:italicμ</jats:italic>m. 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 5jats:italicσ</jats:italic> contrast limits of ∼1 × 10jats:sup−5</jats:sup> and ∼2 × 10jats:sup−4</jats:sup> at 1″ for NIRCam at 4.4 jats:italicμ</jats:italic>m and MIRI at 11.3 jats:italicμ</jats:italic>m, respectively. These contrast limits provide sensitivity to sub-Jupiter companions with masses as low as 0.3jats:italicM</jats:italic> jats:subJup</jats:sub> beyond separations of ∼100 au. Together with existing ground-based near-infrared data, the JWST photometry are fit well by a jats:monospaceBT-SETTL</jats:monospace> atmospheric model from 1 to 16 jats:italicμ</jats:italic>m, 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 jats:inline-formula jats:tex-math

</jats:tex-math> <mml:math xmlns:mml="" overflow="scroll"> mml:milog</mml:mi> <mml:mfenced close=")" open="("> mml:mrow mml:msub mml:mrow mml:miL</mml:mi> </mml:mrow> mml:mrow mml:mibol</mml:mi> </mml:mrow> </mml:msub> mml:mrow <mml:mo stretchy="true">/</mml:mo> </mml:mrow> mml:msub mml:mrow mml:miL</mml:mi> </mml:mrow> mml:mrow mml:mo⊙</mml:mo> </mml:mrow> </mml:msub> </mml:mrow> </mml:mfenced> </mml:math> <jats:inline-graphic xmlns:xlink="" xlink:href="apjlacd93eieqn2.gif" xlink:type="simple" /> </jats:inline-formula> = −4.31 and −4.14, which in turn provides a robust mass constraint of 7.1 ± 1.2 jats:italicM</jats:italic> jats:subJup</jats:sub>. 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.</jats:p>



5109 Space Sciences, 51 Physical Sciences

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Astrophysical Journal Letters

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American Astronomical Society
NASA (NAS5-03127)
French National Research Agency (ANR-20-CE31-0012)
EC ∣ Horizon 2020 Framework Programme (H2020) (885593)
EC ∣ Horizon 2020 Framework Programme (H2020) (819155)