Most of our research is focused on Mars, which is considered to be the next-most hospitable body outside of Earth. The goal is to explore icy satellites in the outer Solar System that could be hospitable. There is a dichotomy between rocky planets that are within a system's Habitable Zones and icy moons that are outside.
Some people think that exomoons may be a good place to look for life outside the Solar System. In a new study, a team of researchers investigated how the orbit of exomoons around their parent bodies could lead to tidal heating. It could help exoplanet-hunters determine which exomoons are more likely to be in the right place.
The research was done by a graduate student and a professor. The paper describing their findings has been submitted for publication in the journal. Multiplanet moon systems in the Solar System inspired their analysis.
The interior oceans of these icy moons are thought to be caused by tidal heating, where the interaction with a larger planet leads to geological activity. Liquid oceans can exist due to the presence of hydrothermal vents at the core-mantle Boundary. Scientists have been hoping for a long time that the heat and chemicals released into the ocean could make these " Ocean Worlds" possible. The email was sent to Universe Today.
“In terms of astrobiology, tidal heating may boost the surface temperature of a moon to a range where liquid water can exist. Thus even systems outside the habitable zone may warrant further astrobiological studies. For example, Europa hosts a liquid ocean due to tidal interactions with Jupiter, although it lies outside the Solar System’s ice line.”
It is likely that similar planets and multi- moon systems can be found throughout the universe. The presence of exomoons has a lot of important implications for life according to Piro.
The formation of the Moon has been thought of in the past. 4.5 billion years ago, life emerged. The molten outer core rotates around a solid inner core in the opposite direction of the planet's rotation. The magnetic field protects Earth from harmful radiation and is what allowed our atmosphere to remain stable over time.
Habitability can be affected by the interaction between a planet and its satellites. The presence of exomoons can be used to explore the interior of exoplanets. The amount of tidal heating depends on a number of factors. It was illustrated by Piro.
“As a planet raises tides on a moon, some of the energy stored by the deformation is transferred into heating the moon. This process is dependent on many factors, including the interior structure and size of the moon, the mass of the planet, planet-moon separation, and the moon’s orbital eccentricity. In a multi-moon system, the eccentricity can be excited to relatively high values if the moons are in resonance, leading to significant tidal heating.”
“In Armen’s work, he nicely shows, in analogy to the tidal heating we see for Io around Jupiter, that resonant interactions between multiple moons can efficiently heat exomoons. By ‘resonant,’ we mean the case where the periods of moons obey some integer multiple (like 2 to 1 or 3 to 2) so that their orbits gravitationally ‘kick’ each other regularly.”
Smaller rocky planets to Neptune-like gas giants and Super-Jupiters were considered to be moons in a 2:1 resonance around the planets. According to their results, the largest tidal heating will occur in moons that are in the right place at the right time. The tidal temperature was 480 K and the tidal luminosity was over 1000 times that of Io.
Future exoplanet and Astrobiology surveys could be affected by these findings. Since exomoons are difficult to detect using conventional methods and current instruments, no one has been confirmed as a candidate. There could be new methods for detecting exomoon.
“First, we have the secondary eclipse method, which is when a planet and its moon move behind a star resulting in a dip in stellar flux observed. If the moon is significantly heated, this secondary dip will be deeper than what is expected from the planet alone. Second, a heated moon will likely expel volatiles like sodium and potassium through volcanism much like the case of Io. Detecting sodium and potassium signatures in the atmospheres of exoplanets can be a clue for exomoon origin.”
Next- generation telescopes like the James Webb will rely on their combination of advanced equipment to detect chemical signatures from exoplanet atmospheres in the future. Direct image of exoplanets will be possible with the ELT and other instruments. The ability to detect chemical signatures of exomoons will allow them to find signs of life.
ArXiv is further reading.
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