Prominent Mid-infrared Excess of the Dwarf Planet (136472) Makemake Discovered by JWST/MIRI Indicates Ongoing Activity
Pál, András; Lellouch, Emmanuel; Moór, Attila; Szakáts, Róbert; Marton, Gábor; Parker, Alex H.; Glein, Christopher R.; Müller, Thomas G.; Wong, Ian; Stansberry, John; Holler, Bryan J.; Protopapa, Silvia; Kiss, Csaba; Szabó, Gyula M.; Farkas-Takács, Anikó; Santos-Sanz, Pablo; Ortiz, Jose Luis; Fernández-Valenzuela, Estela; Vilenius, Esa; Regály, Zsolt; Kalup, Csilla E.
Hungary, Germany, United States, Spain, France, United Kingdom
Abstract
We report on the discovery of a very prominent mid-infrared (18–25 μm) excess associated with the trans-Neptunian dwarf planet (136472) Makemake. The excess, detected by the Mid-Infrared Instrument of the James Webb Space Telescope, along with previous measurements from the Spitzer and Herschel space telescopes, indicates the occurrence of temperatures of ∼150 K, much higher than what solid surfaces at Makemake's heliocentric distance could reach by solar irradiation. We identify two potential explanations: a continuously visible, currently active region powered by subsurface upwelling and possibly cryovolcanic activity covering ≤1% of Makemake's surface or an as-yet-undetected ring containing very small carbonaceous dust grains, which have not been seen before in trans-Neptunian or Centaur rings. Both scenarios point to unprecedented phenomena among trans-Neptunian objects and could greatly impact our understanding of these distant worlds.