Chuck Bednar for redOrbit.com – @BednarChuck
In an attempt to observe how noble gases behave in deep-space conditions, a team of researchers led by the Carnegie Institution for Science developed laboratory techniques to mimic the extreme pressures and temperatures that the elements would be exposed to in that situation.
Noble gases, which include helium and neon, are among the matter that makes up distant planets and even more distant stars. The goal of their research was to find out how the gases would behave under these circumstances and to better understand the atmospheric and internal chemistry of these far-off celestial objects.
As the study authors explained Tuesday in the journal Proceedings of the National Academy of Sciences, they used a diamond-anvil cell to bring the noble gases helium, neon, argon, and xenon to a pressure more than 100,000 times that found in Earth’s atmosphere. They then heated the gases with a laser until they reached temperatures of up to 50,000 degrees Fahrenheit.
Noble gases do not combine with other elements under normal circumstances, and the Carnegie-led research team said that they were particularly interested in the ability of these gases to conduct electricity changed in response to increased pressure and temperature. This data could provide clues about how these gases interact with other materials in extreme conditions.
Improving our understanding of gas giants, white dwarfs
They found that helium, neon, argon, and xenon transform from transparent insulators (meaning that they are unable to conduct the flow of electrons in an electric current) into visible conductors (materials capable of maintaining an electrical current) under conditions that mimic the interiors of different stars and planets.
This discovery could solve some of the mysteries of the solar system, such as why Saturn emits more heat from its interior than would be expected based on its stage of formation. In gas giants like Jupiter and Saturn, helium is an insulator near the surface and becomes more metallic at depths closer to the core of each planet – a change that takes place in conditions where the hydrogen that largely comprises both planets is also metallic.
Scientists predict that helium is dissolved into hydrogen on both planets, but the authors of the study found that Jupiter and Saturn differ when it comes to the behavior of the neon found on each world. Their simulations indicate that neon would remain an insulator on Saturn, even at its core, and would accumulate. This would prevent the core from eroding like on Jupiter, where iron and other materials would dissolve into the surrounding liquid hydrogen.
The researchers believe that this lack of core erosion on Saturn could explain why it is emitting so much more internal heat than Jupiter, as the erosion of a planet’s core causes it to cool down while dense matter is raised upwards while it mixes and converts heat to gravitational potential energy. On Saturn, meanwhile, denser material is able to collect that the planet’s center, leading to hotter conditions.
In addition to potentially helping to solve the mystery of Saturn’s internal heat, the authors said their work could explain why compact white dwarf stars have faint luminosities as they give off residual heat. The atmospheres of these stars are known to contain dense helium, and the lab simulations indicate that the element should be a better conductor than previously believed, thus slowing down the cooling rates of helium-rich white dwarfs and altering their color.
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