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Researchers discover the largest mirror in the universe – a planet that shouldn’t exist

Researchers discover the largest mirror in the universe – a planet that shouldn’t exist

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The European Space Agency’s Khufu space probe is examining an already known exoplanet and discovers something surprising.

Marseille – Venus is the brightest planet in the night sky – the celestial body reflects about 75 percent of the sun’s light, while Earth re-emits only about 30 percent of the light. Now, for the first time, researchers have found a planet outside our solar system that can rival the brightness of Venus: LTT9779b. The exoplanet was discovered by NASA’s TESS spacecraft in 2020, and then studied by the European Space Agency’s Chops spacecraft.

family name: LTT9779 b
He writes: Exoplanet (very hot Neptune)
radius: 4.7 times the radius of the Earth
Dimensions: 29 times the mass of Earth
Duration of one year: 19 hours
Discovery: 2019 by TESS

It turns out that LTT9779 b reflects 80 percent of the light that falls on an exoplanet — it’s the largest known “mirror” in the universe to date, according to one notice European Space Agency ESA. But why does an exoplanet the size of Neptune emit so much light? Astronomer James Jenkins, co-author of the LTT9779 b study, explains so: “Imagine a world on fire near your star, with heavy metal clouds hovering above and titanium droplets falling.” in the journal Astronomy and astrophysics published had become. The exoplanet is surrounded by metallic clouds that are mostly made of silicates and metals such as titanium.

Most planets reflect very little light

Most known planets have a low albedo — the technical term for the amount of light reflected off an object. This is because they either have an atmosphere that absorbs a lot of light, or because the surface of the planet is dark. Exceptions with high albedo are icy worlds with bright surfaces or planets like Venus, which have a reflective cloud layer.

The high albedo of LTT9779 b was a surprise to the researchers, because the side of the planet facing its star is estimated to have a temperature of about 2,000 degrees Celsius. Temperatures over 100°C don’t actually allow clouds of water vapor to form, and 2000°C must be too hot even for clouds made of metal or glass. “It was really a puzzle until we realized we should think of this cloud formation as condensation in the shower after a hot shower,” explains Vivian Parmentier, a co-author of the study.

The researcher goes on to explain: “To heat a bath, you can either cool the air until the water vapor condenses, or you can run hot water until clouds form, because the air is so saturated with water vapor that it can just freeze. Don’t take anything anymore.” Likewise, though From its high temperature, LTT9779 b can form metal clouds because the atmosphere is saturated with silicates and metal vapors.”

Exoplanet LTT9779 b is a surprise to researchers

Exoplanet LTT9779 b is a surprise to researchers for another reason: because of its size and temperature, it’s one of the “superhot Neptunes” — but to date no other planet of this size or temperature class has been discovered as close to its star as LTT9779 b. It is located in the so-called “Neptune Desert”. “It’s a planet that shouldn’t exist,” says researcher Parmenter. We assume that the atmosphere of these planets is far from their star, leaving behind bare rocks.

First author Sergio Hoyer (Marseille Laboratory of Astrophysics) adds to the research team’s theory: “We think these metallic clouds help the planet survive in the hot desert of Neptune. The clouds reflect light and prevent the planet from becoming too hot and evaporating. At the same time, the metal content makes The planet’s high altitude and its atmosphere is heavy and difficult to blow away.”

Artist’s rendering of exoplanet LTT9779b, which reflects about 80 percent of the light that falls on it. This makes it the largest known “mirror” in the universe. © Ricardo Ramirez Reyes (University of Chile)

The European Space Agency’s Cheops probe examined the exoplanet LTT9779 b

The researchers owe the new findings about the exoplanet LTT9779 b to ESA’s “Cheops” probe. This is the first space mission to re-observe and characterize known exoplanets with greater precision. “Unlike large survey missions focused on discovering new exoplanet systems, ‘Cheops’ is flexible enough to quickly focus on targets of interest and achieve coverage and precision that we often cannot achieve by other means.” , explains Maximilian Günther, Esa project scientist for Project Khufu.

Khufu is just one part of a three-part exoplanet mission. The spacecraft is scheduled to follow Plato in 2026 and study Earth-like planets at potentially habitable distances from their stars. The Ariel space probe is also scheduled for 2029, which will specialize in the atmospheres of exoplanets. (unpaid bill)