Two dwarf planets in our solar system, Eris and Makemake, may exhibit enough geothermal activity to maintain oceans of liquid water within them, according to modeling describing new observations made with the James Webb Space Telescope.
“We’re seeing some interesting signs of warm times in cool places,” said planetary geochemist Christopher Glein of the Texas Southwest Research Institute. expression.
found in the deep Kuiper BeltEris is the icy world that was ejected when it was discovered in January 2005. Pluto‘s situation solar system went into crisis. It is only 44 kilometers (27 miles) smaller than Pluto but is 25% larger thanks to the greater concentration of rock in its core. Eris became the prototype dwarf planet. Pluto inevitably had to follow suit. Makemake (“pronounced”)Mah-kay-Mah-kay“) was detected two months after Eris, and at 1,430 km (888 miles) wide, it is about 1,000 km (about 600 miles) smaller than Eris and Pluto.
Relating to: Dwarf Planet Makemake: An Icy Wonder in Pictures
The great distance between them Sun —– Eris is currently 14.4 billion kilometers (8.9 billion miles) away and Makemake is 7.7 billion kilometers (4.8 billion miles) away; This means very little is known about these faraway places dwarf planets.
However, recent observations James Webb Space Telescope They shed new light on worlds by finding a surprising origin of the frozen methane ice on their surfaces.
“We found evidence indicating methane-producing thermal processes at Eris and Makemake,” Glein said.
Methane is a substance known as a hydrocarbon because it consists of a mixture of hydrogen and carbon. atoms (specifically one carbon atom and four hydrogen atoms.) These atoms can be found in different flavors, or “isotopes,” containing the same number of atoms. protons but their numbers are different neutrons.
If the methane on the surfaces of these dwarf planets had accumulated from the primordial planet-forming disk that existed around the young sun 4.5 billion years ago, they would have contained a specific isotope ratio between two isotopes of hydrogen (regular hydrogen with a proton and a proton). deuterium, which consists of zero neutrons and one proton and one neutron. However, the hydrogen isotope ratio measured by JWST differs from the ratio that would be expected if methane were primordial. comets.
“The deuterium/hydrogen ratio points to the geochemical origins of methane produced at depth,” Glein said. “Our data shows that the rocky cores of these worlds have high temperatures for methane to be cooked. Molecular nitrogen can also be produced, and we see this on Eris.”
In other words, hydrothermal reactions, or metamorphic activity, meaning heat and pressure acting on rocks, must have produced the methane deep within Eris and Makemake. So methane must have come to the surface through outgassing or even volcanism.
For methane to form in this way, a temperature exceeding 150 degrees Celsius (about 300 degrees Fahrenheit) is required. These temperatures can only come from radioactive isotopes found in the rocky cores of each dwarf planet, which emit heat as the isotopes decay.
“Hot cores may also indicate potential sources of liquid water beneath their icy surfaces,” Glein said, raising the possibility that Eris and Makemake could possibly contain habitable oceans.
Methane’s rise to the surface (geologically) may have been occurring until recently according to a different isotope ratio (between carbon-12, which has 6 protons and 6 neutrons, and carbon-13, which has 6 protons and 7 neutrons).
“If Eris and Makemake hosted or may still host warm, even hot, geochemistry in their rocky cores, cryovolcanic processes could transport methane to the surfaces of these planets in geologically recent times,” Will Grundy said. Lowell ObservatoryThe person who led the first JWST observations. “We found a carbon isotope ratio that suggests relatively recent resurfacing.”
Related Stories:
— Eris: The First Dwarf Planet
— Dwarf Planets in Our Solar System (Infographic)
— Dwarf Planet Beyond Pluto Has No Atmosphere
Interestingly, the models developed to describe methane formation and outgassing at Eris and Makemake may also apply to: Saturnmoon of the moon Titan. Research A study published earlier this month showed that methane and other carbon-based molecules important to life may not reach Titan’s subsurface ocean after spending some time on the surface, where hydrocarbons are abundant. This cast doubt on the possible habitability of Titan’s ocean. However, if methane and other gases can form geothermally in Titan’s rocky core, as is the case with Eris and Makemake, then Titan’s ocean may receive its carbon chemistry from within the planet rather than from its surface.
The results of methane observations on Eris and Makemake are described in the article published in the April 2024 issue of the journal Icarus.