A new study by scientists Manasvi Lingam (Harvard University; Florida Institute of Technology) and Abraham Loeb (Harvard University) explores the possibility that exoplanets outside of a star’s habitable region, also known as “Goldilock Zone,” might host alien life.
For a planet to be able to keep water or any other liquid, it needs warmth. So far, it was believed that only a star could provide a planet the possibility of getting enough heat. But the two scientists believe that stars aren’t everything. Planets can warm themselves too, from inside. How is that possible? Radioactive decay and primordial heat from the planet’s formation can do that.
Higher radioisotope concentrations may be enough to generate the heat needed to sustain liquid on the planets’ surfaces. And this can occur in the galactic bulge. In astronomy, a bulge is a tightly packed group of stars within a more extensive formation. Due to the lack of dust and gases, bulges tend to have almost no star formation.
Exoplanets outside “Goldilocks Zone” could house alien life
A radioisotope is an atom that has excess nuclear energy. This excess energy can be emitted from the nucleus as gamma radiation, transferred to one of its electrons to release it as a conversion electron, or used to create and emit a new particle from the nucleus. During those processes, the radionuclide is said to undergo radioactive decay.
An exoplanet without a host star’s habitable zone has a tenuous atmosphere. To host a long-lived water ocean, it needs 1,000 times higher radioisotope abundances than that of Earth. An ethane ocean requires only 100 times Earth’s radioisotope abundances.
Loeb and Lingam left aside all common knowledge and thought that maybe not all forms of alien life need what earthly ones do. Perhaps they don’t need water. Maybe ammonia or ethane is the water for them. Perhaps they don’t need the same kind of atmosphere to thrive. Maybe life on an exoplanet outside “Goldilock Zone” isn’t something we already know about. And maybe those two researchers are right.