New discovery: The iron rain planetary environment is close to that of a red dwarf

Artistic hypothetical image of planet WASP-76b in the constellation pisces

Just 640 light-years from Earth, hot molten iron poured down from the sky to water a planet. New research shows that although it is a planet, its atmospheric environment has reached extremes to the level of a red dwarf.

The planet, code-named WASP-76b, is located in Pisces, which is close to its host star and orbits its host star every 1.8 Earth days. And it has the characteristics of synchronous rotation, that is, the time of its rotation of one week is equal to the time of one week of rotation. This means that the planet is always fixed on one side of its star, and this hemisphere is always day, while the other hemisphere is always night.

A new study shows that the average temperature on the wasp-76b side during the day is as high as 2,426 degrees Celsius, and the temperature on the night side is also as high as 1,315 degrees Celsius. In such a high temperature environment, the compound molecules are easily disintegrated into atoms, and the metals are gasified.

Scientists first discovered the exoplanet in 2016. One of its most impressive features is that the atmosphere there is an iron rain. The iron vapor above the daytime hemisphere is blown by strong winds into the night hemisphere, where it condenses into molten iron and falls from the sky. Not only that, but the study also found that its atmosphere contains components of ionic calcium.

"It's a very extreme and rare atmospheric environment, unlike any planet in the solar system." Ray Jayawardhana, dean of the College of Arts and Sciences at Cornell University, one of the principal investigators, told USA TODAY that "the discovery of ionized calcium in the atmosphere means that its upper atmosphere is hotter than previously known, and there may be massive strong winds." In a way, the environment of the upper atmosphere there is no different from that of a red dwarf. ”

The researchers analyzed this information from observations from the Gemini North Telescope in Hawaii. "It's a remarkable fact that these planets are hundreds of light-years from Earth, but we can analyze the composition of the atmospheres on those planets using telescopes on the ground." Jayawadhana said.

The study was published Sept. 28 in The Astrophysical Journal Letters.

In addition to iron rain, scientists have also found various strange rains on other planets. For example, it rains glass on HD 189733 b; in the solar system, in the high-pressure environment on Neptune, some carbon forms diamond crystals, and it rains diamonds.

But Neptune doesn't rain the same way as Earth. Neptune is a giant ice ball, much less dense than the rocks on Earth. The resulting diamond sinks toward the center of the earth within a layer of high-density, high-temperature liquid matter.