hot Jupiter
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Credit: NASA/ESA/A. Schaller (STScI)

This planet is so scorching that metals actually vaporize into the atmosphere

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Apr 24, 2020

There are hot planets, and then there are unbelievably, unbearably, insufferably hot planets.

Imagine an alien world torrid enough to not just melt, but vaporize metal. MASCARA-2 b (whose name has absolutely nothing to do with makeup) is that planet. A team of Yale scientists recently used the EXPRES (Extreme PREcision Spectrometer) spectrograph to investigate this hot Jupiter, a gargantuan ball of gas that orbits extremely close to its star and gets roasted in the process. Turned out that metals can’t stay solid or even liquid in that heat. Iron, chromium, and magnesium vapor were found in its atmosphere.

Never mind that human lungs could never breathe that. If you landed there, you’d probably be vaporized yourself before you could puff one breath.

Hot Jupiters like MASCARA-2 b (and NTGS-10b, above) are Jupiter-like in that they are gas giants, but more like versions of our Jupiter in the seventh circle of hell in Dante’s Inferno. Their orbital periods are less than 10 days — compare that with our Jupiter’s orbital period of 12 years. The shorter the orbital period, the closer that planet is to its host star, so you can guess where this is going. MASCARA-2 b’s orbit is a hundred times closer to its star than Jupiter’s is to the Sun. How they get so close is still a mystery. Many scientists believe they form further out in their star systems and migrate closer, but there has been much debate about how that migration occurs.

“Hot Jupiters provide the best laboratories for developing analysis techniques that will one day be used to search for biosignatures on potentially habitable worlds,” said Debra Fischer, a Yale astronomer and Eugene Higgins Professor of Astronomy, who co-authored a study recently accepted by Astronomy and Astrophysics.

MASCARA-2 b is an extreme hot Jupiter. Twenty-eight quadrillion miles from Earth, its atmosphere blazes at over 3,140 degrees Fahrenheit. Not hot enough? Iron in its regular form will only vaporize at 5,184 degrees Fahrenheit. What Fischer’s team actually found were iron ions Fe I and Fe II, along with sodium ion Na I, which they think emerged in the atmosphere, which is so hot and bothered it is actually inflated. Magnesium ion Mg I and chromium ion Cr II were also detected. Ions form when atoms gain or lose their outermost electrons. The bigger the ions, the lower the boiling point, because they stay further apart than smaller ions and need less heat energy to separate them.

So how did EXPRES find out there was metal in the air? EXPRES was designed by Yale scientists to both find Earthlike planets (based on how they gravitationally influenced their stars) and find out what is swirling in the atmospheres of distant worlds. After it was installed on the Lowell Discovery Telescope near Flagstaff, Arizona, it was able to pick up on the chemicals MASCARA-2 b left behind after it crossed the direct line of sight between our planet and its star.

“Atmospheric signatures are very faint and difficult to detect,” said grad student Sam Cabot, another co-author of the study who also led the data analysis. “Serendipitously, EXPRES offers this capability, since you need very high-fidelity instruments to find planets outside our own solar system.”

EXPRES is hardly finished. It will be collaborating with other ultra-precise spectrometers to discover more unreal things out there, so get ready for more hot action.

(via Yale University/Astronomy and Astrophysics)


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