This week in super-sized planets reveals some of the secrets of magnesium shields and shrouds. In the former instance, scientists at the Carnegie Institution of Washington were able to mimic the mineral conditions of certain super-planets within a laboratory and published their findings in the Science journal earlier this week.
As it turns out, planets of this size have fewer physical properties in common with Earth and other terrestrial planets than scientist once thought. Their huge mass results in very high internal pressure, which in turn causes melting temperatures so high that their interiors don't separate into distinct layers of mantle and core. These high temperatures may allow magnesium oxide - which on Earthlike planets exists in rock form - to act as a liquid metal, possibly even generating a magnetic shield to protect potential "life from harmful radiation." The lead author, R. Stewart McWilliams, expanded on this discovery in an interview with the wonderfully named SPACE.com:
"It is often said that life on planets may require the presence of a strong magnetic field to protect organisms from dangerous radiation from space such as cosmic rays - at least this may be true for certain types of life, similar to humans, that live on a planet's surface," McWilliams said. "We find that magnetic fields may occur on a wider range of planets than previously thought, possibly creating unexpected environments for life in the universe."
McWilliams noted that much remains unknown about the physics of super-Earths, and that researchers need to generate computer models to see where and how this liquid metal might exist in nature.
The evaporating cloud is unusual
in that it appears to be infused with the element magnesium, which absorbs some of its star's light. This renders the entire system invisible when viewed in the near-ultraviolet part of the light spectrum, although the dying planet is otherwise detectable.
"It's like the planet is suffering the sad end of being evaporated away ... and the star has drawn a privacy veil over the whole sordid affair," Haswell said.
Astronomers have long hypothesized that hydrogen can escape gas giants so quickly that they carry other elements along in a "blowoff", and the presence of magnesium in WASP-12b's gas cloak appears to confirm the existence of that process. Magnesium: pulling double duty this week as science writers wax surprisingly and lovingly poetic about planetary death.