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Cheops Unveils Mirror-Like Exoplanet Radiating Intense Heat

Cheops unveils mirror-like exoplanet radiating intense heat with a rapid orbital period of just 19 hours. Planet LTT9779b, the ultra-hot exoplanet has claimed the title of the shiniest exoplanet ever detected.

Rhyley Carney
Jul 11, 202326023 Shares441065 Views
Cheops unveils mirror-like exoplanet radiating intense heatwith a rapid orbital period of just 19 hours. Planet LTT9779b, the ultra-hot exoplanet has claimed the title of the shiniest exoplanet ever detected.
This scorching celestial body stands out due to its reflective metallic clouds, comprising silicates and metals like titanium. Notably, LTT9779b holds the distinction of being the largest known "mirror" in the universe, capturing the attention of astronomers. Situated approximately 262 light-years away from Earth, its remarkable characteristics were initially identified by NASA's TESS mission in 2020, supported by ground-based observations conducted by the European Southern Observatory in Chile.
Recognizing the significance of this discovery, the European Space Agency's Cheops mission embarked on follow-up observations to further investigate the unique properties of planet LTT9779b. Through coordinated efforts across these missions and instruments, scientists have obtained invaluable insights into the nature of this extraordinary exoplanet.
ESA's Cheops mission played a pivotal role in acquiring crucial measurements that unveiled LTT9779b's extraordinary light-reflecting capabilities. The data revealed that this exoplanet reflects a remarkable 80% of the light emitted by its host star, surpassing even the brilliance of Venus within our own solar system.
Among celestial bodies visible in our night sky, the moon takes the lead in terms of brightness, followed by Venus, whose dense cloud layer reflects approximately 75% of the sunlight it receives. In contrast, Earth reflects a mere 30% of incoming sunlight.
“Imagine a burning world, close to its star, with heavy clouds of metals floating aloft, raining down titanium droplets,” says James Jenkins, astronomer at Diego Portales University and CATA (Santiago, Chile). James is one of the co-authors of a scientific paper featured in today's issue of the journal Astronomy & Astrophysics, unveiling groundbreaking research.

A Sky With Metal Clouds

The albedo of an object refers to the fraction of light it reflects. Typically, planets exhibit low albedo due to factors such as atmospheric absorption or dark and rough surfaces. However, exceptions exist in the form of frozen ice worlds or planets with reflective cloud layers, like Venus.
The revelation of LTT9779 b's high albedo came as a surprise because the side of the planet facing its star is estimated to reach scorching temperatures of around 2000 °C. Cloud formation is inhibited at temperatures exceeding 100 °C, rendering the formation of water clouds impossible.
Moreover, the extreme heat of this exoplanet's atmosphere would ordinarily preclude the existence of clouds composed of metal or glass. Therefore, the presence of highly reflective clouds on LTT9779 b challenges current understanding and poses an intriguing puzzle for scientists to unravel.
Vivien Parmentier, a researcher at the Observatory of Côte d’Azur (France) and co-author of this research explains:
It was really a puzzle, until we realized we should think about this cloud formation in the same way as condensation forming in a bathroom after a hot shower. To steam up a bathroom you can either cool the air until water vapor condenses, or you can keep the hot water running until clouds form because the air is so saturated with vapor that it simply can’t hold any more. Similarly, LTT9779 b can form metallic clouds despite being so hot because the atmosphere is oversaturated with silicate and metal vapors.- Vivien Parmentier, researcher at the Observatory of Côte d’Azur in France

The Shiniest Known Exoplanet: LTT9779 B

The Planet That Shouldn’t Exist

LTT9779 b is more than just shiny; it possesses some astonishing qualities. Its immense size and scorching temperature classify it as an "ultra-hot Neptune." However, what sets it apart is its close proximity to its star. Unlike any other planet of its size and mass, LTT9779 b dwells within the realm known as the "hot Neptune desert."
With a radius 4.7 times that of Earth, LTT9779 b completes a full orbit around its star in a mere 19 hours. It is important to note that all previously identified planets with orbital periods shorter than a day were either "hot Jupiters" – colossal gas giants with a radius at least ten times that of Earth – or rocky planets smaller than twice Earth's radius.
“It’s a planet that shouldn’t exist,” says Vivien. “We expect planets like this to have their atmosphere blown away by their star, leaving behind bare rock.”
According to Sergio Hoyer, the lead author from the Marseille Astrophysics Laboratory, it is believed that the presence of metal clouds plays a crucial role in enabling the survival of LTT9779 b within the hot Neptune desert. These clouds serve two important functions: reflecting light to prevent excessive heating and evaporation of the planet, and imparting a heavy and robust quality to both the planet itself and its atmosphere, making it more resistant to being blown away.
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