Illustration for article titled The galaxys hottest planet uses a shockwave shield to save its atmosphere

The exoplanet WASP-12b, located 867 light-years from Earth, is just two million miles away from its star. It has a surface temperature of 4000 degrees Fahrenheit, and it has to take some seriously extreme measures to keep its atmosphere intact.


Researchers at the Open University discovered that WASP-12b appeared to have a giant cloud of material in front of it, as though its parent star was stripping away part of its atmosphere. The planet, which is about twice Jupiter's size, seems to be far too close to its star to survive, so how is it more or less holding together?

The answer, according to the researchers, is that the planet's magnetosphere throws up a giant magnetic shield to protect it from its star. Here's how it works:

Scientists using computer simulations to explain observations of the ultrahot alien planet WASP-12b located around a star 867 light-years from Earth say the exoplanet could be pushing a shock wave - called a bow shock - ahead of it as it plows through a supersonic headwind while orbiting its star. The effect is similar to the shock wave ahead of a supersonic aircraft.

WASP-12b orbits a yellow dwarf star that spews out charged particles much like the sun's solar wind. As WASP-12b orbits the star, the exoplanet compresses the material in front of it, creating the bow shock. This shock wave could then protect WASP-12b from the rain of charged particles that would otherwise erode its atmosphere.


While WASP-12b is just the most extreme case of a planet that needs a bow shock to protect it from its star, the researchers think that many other exoplanets have similar orbital conditions that would allow for similar phenomena.


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