Super Earths May Get Their Magnetic Fields From Magnesium Oxide
November 23, 2012

What’s Underneath The Surface Of The Typical Super Earth?

Brett Smith for - Your Universe Online

Astronomers have been spotting so-called ℠Super Earths´ at a regular rate over the past few years and new research by a team of American physicists sheds a light on some of the forces at work below the surface of these terrestrial giants.

According to the team´s report in the journal Science Express, magnesium oxide, a key ingredient in the mantles of rocky planets, behaves differently within many of these newly discovered planets or at the Earth´s core where the pressure and heat can reach extreme levels.

Led by Stewart McWilliams from the Carnegie Institution, the team observed magnesium oxide at pressures between 3 million and 14 million times atmospheric pressure while being heated at temperatures as high as 90,000 degrees Fahrenheit. They recorded unique changes to the compound´s molecular bonding as the magnesium oxide underwent these various conditions, including a transformation to a new high-pressure solid phase.

They also noted that when melting, magnesium oxide changes from an electrically insulating material like quartz to a conductive metal, allowing for electrons to flow through it–resulting in the creation of a magnetic field.

"Our findings blur the line between traditional definitions of mantle and core material and provide a path for understanding how young or hot planets can generate and sustain magnetic fields," McWilliams said.

These magnetic fields can serve to protect a planet from deadly solar radiation, giving any life there a chance to perpetuate. The findings also imply that the cooling Earth's magma ocean might have been able to generate a magnetic field.

Over 40 Super Earths have been discovered since the first one was identified in 1992. The term only implies the size of the planet and not its habitability. Those planets that could potentially be hospitable for humans and known as orbiting a star in a “Goldilocks Zone,” where the surface temperature would be just right for multi-cellular life as we know it. One Super Earth orbiting within a Goldilocks Zone just 42 light years away was identified earlier this month in a paper published by scientists from the University of Hertfordshire in the United Kingdom.