In the ongoing debate as to whether or not we are alone in the universe, many skeptics have pointed to how quickly the odds shrink when considering what has come to be known as the “Goldilocks Principle.” In order to support life as we know it, a planet must not be too close as well as not too far from the star it orbits in order to allow for the existence of liquid water (“not too hot, not too cold – just right”).
Now, with new research conducted by scientists from Ohio State University (OSU) using findings from the European Southern Observatory (ESO) in Chile’s Atacama Desert, it has come to light that achieving these conditions may not be as difficult as once thought. Indeed, the preliminary study has already identified seven stars in our own galaxy that appear capable of supporting solar systems far more suited to harboring life than our own.
Researchers, including Cayman Unterborn and Wendy Panero from OSU’s School of Earth Sciences, analysed eight “sun twins” (stars similar to the sun) in the Milky Way Galaxy for levels of radioactive elements needed by planets to generate their own heat. Seven out of the eight stars studied had higher levels of thorium and uranium than our sun. This indicates that any terrestrial planets formed around those stars would have similarly high levels, leading to warmer cores and mantles than those of our own planet.
“If it turns out that these planets are warmer than we previously thought, then we can effectively increase the size of the habitable zone around these stars by pushing the habitable zone farther from the host star, and consider more of those planets hospitable to microbial life,” Unterborn said at an American Geophysical Union meeting this month.
A terrestrial planet’s core starts out hot, but certain levels of radioactive elements like uranium and thorium are needed to maintain heat over time. This heat is crucial for tectonic activity, the formation of an atmosphere, and the existence of liquid water.
Theoretically, terrestrial planets orbiting the stars studied would be around 25 percent warmer due to higher levels of self-generated heat. Planets rich in thorium are of particular interest, as the half-life of this element is longer than uranium’s, meaning those planets stay warmer for longer, allowing more time for life to come about.
“The elements created in a supernova determine the materials that are available for new stars and planets to form,” Unterborn explained. “The solar twins we studied are scattered around the galaxy, so they all formed from different supernovae. It just so happens that they had more thorium available when they formed than we did.”
Unterborn used data collected using ESO’s High Accuracy Radial Velocity Planet Searcher Spectrometer. Such advanced technology is continuing to be developed in Chile, as the country remains committed to its role as a world leader in astronomy research.
Due to its almost non-existent humidity and clear skies, the Atacama is the planet’s premier location for astronomy. Chile is home to almost half the world’s telescope infrastructure, and this is set to increase to over two thirds by 2018.