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HD 63433 d represents the smallest confirmed exoplanet less than 500 million years old. Its diameter is approximately 1.1 Earth diameters. It orbits the sun-like star HD 63433 or TOI 1726 at a distance that is eight times smaller than the distance from the Sun to Mercury.
Scientists suggest that the planet, because of its temperature, likely lacks a full atmosphere and its diurnal side is a lava hemisphere.
