According to astronomers at the University of Washington, Earth-like planets orbiting close to small stars may possess magnetic fields that can protect their surfaces from stellar radiation. Scientists believe that these magnetic fields, or forces created by electric currents, could be similar to that of our own Earth, which may be conducive to life. The findings are now published in Astrobiology.
EARTH-LIKE PLANETS SHOW SIGNS OF MAGNETIC FIELDS
Researchers were able to come to this conclusion after using computer simulations to model Earth-mass planets in close orbit around low-mass M dwarf stars. Such a star, among the most common in the galaxy, is small and dim, which means its habitable zone – or the region around the star within which planetary-mass objects can maintain liquid water on their surfaces – is relatively close in.
Thus, a planet that orbits very closely to its star may become tidally locked due to the star’s strong gravitational pull. The same phenomenon can be observed in the Moon, which has its near side forever facing the Earth. According to Peter Driscoll, a geophysicist at the Carnegie Institution in Washington, D.C. and the lead author of the paper, this kind of tidal-locking could ultimately heat the interior of earth-like planets.
Would this cause the planets to be “roasted by gravitational tides?” What is the effect of tidal heating on magnetic fields across long periods of time? These were some of the questions that scientists wanted to answer.
WHAT THE DATA REVEALS
Up until this discovery, it was generally assumed by astronomers that tidally locked planets were unlikely to hold protective magnetic fields. Rory Barnes, an assistant professor of astronomy, expected that the tidal heating would actually suppress the planet’s own core heat flow – which is the most important driver of magnetic fields.
Much to the surprise of the scientists, however, the opposite seemed to be true. Based on the collected data, which combined models of orbital interactions and heating with thermal evolution planetary interiors, such magnetic fields could actually be sustained for billions of years – at earth-like levels too; in fact, the more tidal heating a planet experiences, the better its mantle is able to dissipate the heat, which in turn, cools the core and helps to form a strong magnetic field.
