HAT-P-26b: A Neptune-mass exoplanet with a well-constrained heavy element abundance

• Autores: Hannah R. Wakeford, David K. Sing, Tiffany Kataria
• Localización: Science, ISSN 0036-8075, Vol. 356, Nº 6338, 2017, págs. 628-631
• Idioma: inglés
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• Resumen

  • A correlation between giant-planet mass and atmospheric heavy elemental abundance was first noted in the past century from observations of planets in our own Solar System and has served as a cornerstone of planet-formation theory. Using data from the Hubble and Spitzer Space Telescopes from 0.5 to 5 micrometers, we conducted a detailed atmospheric study of the transiting Neptune-mass exoplanet HAT-P-26b. We detected prominent H2O absorption bands with a maximum base-to-peak amplitude of 525 parts per million in the transmission spectrum. Using the water abundance as a proxy for metallicity, we measured HAT-P-26b’s atmospheric heavy element content (Embedded Image times solar). This likely indicates that HAT-P-26b’s atmosphere is primordial and obtained its gaseous envelope late in its disk lifetime, with little contamination from metal-rich planetesimals.