Kavli Affiliate: Dimitri Mawet| Summary:We present new JWST/NIRCam 4-5 $μ$m (F410M, F430M) and JWST/MIRI 18-25 $μ$m (F1800W, F2100W, F2550W) imaging detections of the nearby (3.6 pc) cold (275 K) gas giant exoplanet $ε$ Ind Ab. The F2550W detection of $ε$ Ind Ab constitutes the longest wavelength image of an exoplanet acquired to date. Combining three decades of radial velocity monitoring, Gaia-Hipparcos absolute astrometry, and relative astrometry from direct imaging (including the new NIRCam astrometry), we conduct a comprehensive re-analysis of $ε$ Ind Ab’s orbit and obtain a dynamical mass $M_rm Ab = 6.5^+0.7_-0.6;M_rm Jup$. Using $ε$ Ind Ab’s NIRCam and MIRI photometry, we assemble the first 4-25 $μ$m spectral energy distribution (SED) of a cold gas giant outside the Solar System. The NIRCam photometry supports a metal-enriched atmosphere for $ε$ Ind Ab based on analysis with atmospheric model grids, consistent with predictions from the giant planet mass-metallicity relation. While the current data do not provide definitive evidence for or against the presence of water ice clouds, we tentatively find that the H$_2$O vapor absorption-dominated F2550W photometry is systematically brighter ($>1σ$, but $<2σ$) than predictions from cloud-free/rainout chemistry models and better explained by a cloudy model. We calculate a bolometric luminosity of $log L_rm bol/L_odot = -7.23 pm 0.03$ dex by directly integrating $ε$ Ind Ab’s SED. Combining this with the planet’s dynamical mass and age ($3.5 pm 1.0$ Gyr), we demonstrate excellent agreement with evolutionary model predictions in a new regime of low luminosities, low masses, and old ages. Our results establish $ε$ Ind Ab as a benchmark system for planetary evolution studies and set the stage for the detailed atmospheric characterization of this frigid extrasolar world.| Search Query:arXiv Query: search_query=au:”mawet dimitri”&id_list=&start=0&max_results=10Read More