“A planet that shouldn’t exist” – a huge “mirror” in the universe that surprises the research team

The European Space Agency’s Cheops probe is closely examining the exoplanet LTT9779b and making several surprising discoveries.

Marseille – Venus is the brightest planet in the night sky, reflecting about 75 percent of the sunlight, compared to Earth, which reflects only about 30 percent of the light. Now, for the first time, a planet outside our solar system has been discovered that can rival Venus in terms of brightness: LTT9779b. In 2020, this exoplanet was discovered by NASA’s TESS spacecraft, and later studied by the European Space Agency’s Chops spacecraft.

It turns out that LTT9779 b reflects about 80 percent of the incident light, as does a Communication from the European Space Agency he is called. This makes the exoplanet the largest known “mirror” in the universe to date. Astronomer James Jenkins, co-author of the book in the journal Astronomy and astrophysics Published study via LTT9779 b. “Imagine a world on fire near your star, where clouds of heavy metal swirl in the sky and titanium droplets fall,” says the researcher. These metallic clouds, composed mostly of silicates and minerals such as titanium, surround the planet outside the solar system.

Exoplanet LTT9779 b is a giant “mirror” in the universe

The vast majority of known planets have a small amount of reflected light (called an albedo). This is either because they have an atmosphere that absorbs a lot of light, or because the planet’s surface is opaque. However, there are exceptions where the albedo is high, such as icy worlds with bright surfaces or planets like Venus, which have a reflective cloud layer.

The unusually high albedo of LTT9779 b particularly surprised the researchers because the side of the planet facing its star is estimated to have a temperature of about 2,000 degrees Celsius. Under normal conditions, temperatures above 100°C do not allow clouds of water vapor to form, and at 2000°C clouds of metal or glass should not be possible either. “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.

A reflective exoplanet shrouded in metallic clouds

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.”

The exoplanet LTT9779 b surprised researchers for another reason: because of its size and temperature, it ranks among the “superhot Neptunes.” However, no other planet of this size or temperature class has been detected 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.

Mineral clouds help the planet survive in the “Neptune desert”.

First author Sergio Hoyer (Marseille Laboratory of Astrophysics) explains 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 high metallic content makes The planet and its atmosphere are heavy and hard to blow away.”

The latest findings about exoplanet LTT9779 b are the result of research conducted with ESA’s Cheops probe. This space mission is the first because it is focused on re-observing and characterizing previously known exoplanets. Maximilian Günther, ESA project scientist for the Cheops project, explains: “Unlike large survey missions focused on discovering new exoplanet systems, Cheops is flexible enough to quickly focus on targets of interest, establish cover and achieve a precision that we often cannot achieve. any other way.”

Machine assistance was used in this editorial article. The article was carefully screened by editor Tanya Banner before it was published.