Liquid water is said to be a necessity to life. Amazingly, however, there could be conducive conditions of life far away in an area that is not near a sun. A group of researchers working on the Excellence Cluster ORIGINS at LMU and the Max Planck Institute of Extraterrestrial Physics (MPE) has demonstrated how moons of free-floating planets can retain their water oceans as liquid to as long as 4.3 billion years through dense hydrogen atmospheres and tidal heating – that is to say, roughly as long as Earth has been around and complex life can evolve.
Planetary systems are usually created when the conditions are not steady. In the event of close approach of young planets they have the ability to launch one another out of orbit. This results in free-floating planets (FFPs) that move around the galaxy with no parent star. A previous paper by LMU physicist Dr. Giulia Roccetti had indicated that gas giants that were thrown out in this manner do not always lose their moons in the process.
Oceans remain in their liquid state because of tidal heating
The ejection however does change the orbits of the moons. They are elongated to a high extent in which their distance to the planet is constantly varying. This leads to the tidal forces rhythmically deforming the lunar body, compressing the body interior, and creating heat due to friction. This tidal heating can be adequate to keep oceans of liquid water on the surface – without the power of a star, and in the coolness of interstellar space.
Hydrogen as stable heat trap
It is the atmosphere that dictates whether this heat remains on the surface or not. Carbon dioxide is a good greenhouse gas on earth. Prior research had shown that carbon dioxide would be able to stabilize life-supportable conditions on exomoons of up to 1.6 billion years. In really low temperatures of free-floating systems, however, carbon dioxide would condense, lose the protective effect on the atmosphere and the heat to escape.
Thus, the scientists of astrophysics, biophysics, and astrochemistry started to research the possibilities of the hydrogen-rich atmospheres being the alternative heat traps. Despite the fact that the molecular hydrogen is mostly transparent to infrared radiation, an important physical phenomenon occurs under high pressures: collision-induced absorption. During this process, hydrogen colliding molecules create temporary complexes, which are able to take up the thermal radiation and store it in the atmosphere. Simultaneously, hydrogen is a stable element even at the lowest temperature.
Parallels to early Earth
The results also provide new insights to the origin of life. The cooperation with the team of Professor Dieter Braun enabled us to understand that the cradle of life does not always need a sun, says David Dahlbudding who is a doctoral researcher at LMU and the lead author of the study. According to the case, there was a distinct relationship between these moons that were far away and the early Earth, which had high levels of hydrogen due to asteroid impact in order to form conditions that supported life.
The tidal force was even capable of providing heat, as well as, chemical development processes. There is deformation periodically, which produces local wet-dry cycles, where water evaporates and condenses. These cycles have been regarded as a significant process of the formation of complex molecules and may make essential steps in the direction to the emergence of life.
Life-friendly moons in interstellar space
The free-floating planets are believed to be common. It has been estimated that these so-called nomadic planets in the Milky Way may be as numerous as the stars. Their moons could also offer long term stable habitats. The new discoveries were therefore able to considerably expand the range of potential habitats in which life might exist – and indicate that life would not only exist but also be able to survive even in the darkest parts of the galaxy.
Read More:
Watching water droplets merge on the International Space Station
Webb space Telescope Captures Clearest View of Neptune’s Rings, Unusual Moon ‘Triton’
What are the conditions suitable for life on distant moons added by Arun Kumar N on
View all posts by Arun Kumar N →