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arXiv · 2609.36160

PHAROS: Panchromatic spectral energy distributions of solar-like stars across evolutionary stages

Viktor Sumida·Raissa Estrela·Eric Mamajek·Pin Chen·Adriana Valio
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Abstract

Panchromatic stellar spectral energy distributions (SEDs) provide the wavelength-dependent irradiation fields required for studies of exoplanet atmospheres, photochemistry, atmospheric escape, and habitability. We present PHAROS, the Panchromatic Habitable-world Archive of Radiation from Observed Solar-like stars, a first release of fifteen component-traceable SEDs for nearby FGK stars spanning adopted ages of 0.26--6.5\,Gyr. The catalogue covers 0.5--5000\,nm and combines archival \textit{XMM-Newton} and \textit{Chandra} high-energy constraints, semiempirical extreme-ultraviolet (EUV) reconstructions, \textit{HST} and \textit{IUE} ultraviolet spectra, Gaia DR3 XP and ancillary optical spectrophotometry, and PHOENIX photospheric extensions. When X-ray data support spectral modelling, target-specific coronal plasma models define the high-energy segment and anchor the EUV normalisation; otherwise, empirical high-energy templates are scaled to literature luminosity constraints. Each SED preserves segment-level provenance, distinguishing directly observed intervals from reconstructed components, empirical templates, bridges, and model-derived extensions. The largest diversity occurs at X-ray, EUV, and ultraviolet wavelengths. Younger age-context groups generally show stronger high-energy output relative to their photospheric continua, although the dispersion within each group shows that age alone does not uniquely determine the irradiation environment. PHAROS provides traceable panchromatic irradiation fields for studies of planetary atmospheres, photochemistry, atmospheric escape, forward modelling, retrievals, and interpretation of future direct-imaging observations, including those anticipated for NASA's Habitable Worlds Observatory.

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Viktor Sumida, Raissa Estrela, Eric Mamajek, Pin Chen, Adriana Valio. 2026-09-28. PHAROS: Panchromatic spectral energy distributions of solar-like stars across evolutionary stages. https://arxiv.org/abs/2609.36160

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