Savannah: Scientists have discovered a two-faced skeleton of an old star nicknamed "Janus." It's the first white dwarf we've ever seen where one side is composed of hydrogen and the other is helium.

Soo, the gravity of white dwarfs is so strong, that heavier elements sink to the center while lighter ones float on the surface. Hydrogen and helium are both light, but hydrogen usually floats on the outer surface of the star until it cools down and sinks, and helium takes its place. So the discovery team might've caught Janus during its transition from one phase into the other.

The team has two hypotheses for what's happening: One is that Janus is surrounded by an asymmetric magnetic field, preventing the mixing of elements on the more magnetic side; another is that the magnetic field is affecting the gas surface pressure, allowing hydrogen to pool up in places where the fields are strongest.

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