Unveiling the atmosphere of the super-Jupiter HAT-P-14 b with JWST NIRISS and NIRSpec (2504.08903v1)

Abstract: We report the combined JWST NIRSpec/G395H and NIRISS/SOSS transmission spectrum of the transiting super-Jupiter HAT-P-14 b, from 0.60 $\mu m$ to 5.14 $\mu m$. Initial analysis of these data reported a near-featureless spectrum at NIRSpec wavelengths range (2.87 $\mu m$ to 5.14 $\mu m$) consistent with the small atmospheric scale height of the planet and unexplained bumps and wiggles at NIRISS wavelengths range (0.6 $\mu m$ to 2.8 $\mu m$). Here, we produce a self-consistent spectrum of HAT-P-14 b's atmosphere with an up-to-date reduction. We detect H$2$O (3.09 $\sigma$) both across NIRISS/SOSS wavelengths range and at the bluest end of NIRSpc/G395H as well as a gray cloud deck (1.90 $\sigma$). We constrain the atmospheric metallicity of HAT-P-14 b to be roughly Solar, with [Fe/H] $= -0.08^{+0.89}{-0.98}$, consistent with the planet mass-metallicity relationship. The differences compared to previous works are likely due to the improved STScI jwst pipeline, which highlights the need to reanalyze the early NIRISS/SOSS transiting exoplanet targets with the latest methods. As HAT-P-14 b is placed as the 805th best target for transmission spectroscopy according to Transmission Spectroscopy Metrics (TSM), our results showcase JWST's unparalleled photometric precision which can easily characterize a thousand exoplanets' atmospheres through transmission spectroscopy.