biostudies-literatureUnknown16(1)Fernandez-Valenzuela EStellar occultations, when a distant object passes in front of a star and casts a shadow on Earth, are a powerful tool to probe the physical properties of solar system bodies. They enable precise size and shape measurements and can reveal rings, satellites, atmospheres, or surface features. Here we present results from two stellar occultations by Hi'iaka, dwarf planet Haumea's largest satellite, observed in April 2021. The second event yielded the first documented multi-chord occultation involving a trans-Neptunian satellite other than Charon. Combining these data with photometric observations, we find that Hi'iaka is a triaxial ellipsoid with a volume-equivalent diameter of 370 ± 20 km and a density of 640 ± 80 kg/m³, indicating a porous interior. The visible geometric albedo is 0.76±0.15Nature communications10926https://www.ebi.ac.uk/biostudies/studies/S-EPMC12686452biostudies-literatureAccurate geometric albedo, shape, and size of Hi'iaka from a stellar occultation.PMC12686452Hanna BHoller BJSicardy BLangill PA'Hearn JAHolcomb EKretlow MAssafin MMorales NEarls BOrtiz JLRommel FLEncardes DBraga-Ribas FAissa DBMonin DFerrais MBenkhaldoun ZMorales RBarnes JAlarcon MRFisher RSJehin ECastro-Tirado ACaton DBurdanov AJunior ARGFernandez-Garcia EJWarner EMorgado BRyan ABenedetti-Rossi GGrigahcene Zde la Vega AGonzalez HMortensen LEAlvarez-Candal ALicandro JVieira-Martins RSteel SPal AMiller WJVachier FDesmars JIglesias-Marzoa RSouami DGalindo-Guil FJCamargo JIBConti DFrancini RFeiden GAFernandez-Valenzuela EDuffard RGoncalves RFlynn RGibson TCRengstorf AWalker GDunford BFraser WBuie MWVara-Lubiano MKamin RFroetschel JStolle-McAllister GKreyche SMde Wit JSantos-Sanz PRustamkulov ZSerra-Ricart MKiss CLecacheux JOlsen ALuken AfalseAccurate geometric albedo, shape, and size of Hi'iaka from a stellar occultation.Stellar occultations, when a distant object passes in front of a star and casts a shadow on Earth, are a powerful tool to probe the physical properties of solar system bodies. They enable precise size and shape measurements and can reveal rings, satellites, atmospheres, or surface features. Here we present results from two stellar occultations by Hi'iaka, dwarf planet Haumea's largest satellite, observed in April 2021. The second event yielded the first documented multi-chord occultation involving a trans-Neptunian satellite other than Charon. Combining these data with photometric observations, we find that Hi'iaka is a triaxial ellipsoid with a volume-equivalent diameter of 370 ± 20 km and a density of 640 ± 80 kg/m³, indicating a porous interior. The visible geometric albedo is 0.76±0.152025-01-01T00:00:00Z2025 Dec2026-06-08T04:59:55.162Z2026-06-08T03:08:45.284ZS-EPMC126864524132634110.1038/s41467-025-65749-1