The scorching exoplanet that acts like a mirror: Bizarre world with titanium clouds is discovered 260 light-years from Earth
- The hot exoplanet appears to be wrapped in metallic clouds made of titanium
- It reflects 80% of light, making it the universe’s most reflective known object
When you think of bright objects in the night sky, the moon or Venus might spring to mind.
But these objects pale in comparison to a new world, which scientists say is so extreme that it probably shouldn’t exist.
The blazingly hot exoplanet appears to be wrapped in metallic clouds made of titanium and silicates that reflect a whopping 80 per cent of light back into space.
This makes it the universe’s most reflective object known, overtaking Venus, which reflects about 75 per cent of incoming light.
‘It’s a giant mirror in space,’ said James Jenkins of Diego Portales University, co-author of the study.
The blazingly hot exoplanet appears to be wrapped in metallic clouds made of titanium and silicates that reflect a whopping 80 per cent of light back into space (artist’s impression)
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The planet, named LTT9779b, and its star are located about 264 light years from Earth in the direction of the constellation, Sculptor.
The planet’s diameter is about 4.7 times greater than Earth, and it orbits very close to its star, meaning its surface temperature is about 3,270°F (1,800°C) – hotter than molten lava.
With its star so close, it is a wonder it has any atmosphere at all, according to the researchers.
An atmosphere with water-based clouds, as on Earth, would have been blown away by solar radiation long ago.
But they believe its clouds are metallic, a combination of titanium and silicate.
‘We even think that the clouds could condense into droplets, and have titanium rain falling in parts of the atmosphere,’ Jenkins said.
The researchers studied the planet using the European Space Agency’s CHEOPS orbiting telescope.
‘No other planet like this has been discovered to date,’ said astronomer and study lead author Sergio Hoyer of the Marseille Astrophysics Laboratory in France.
Possessing an atmosphere while orbiting so close to its star makes it ‘a planet that shouldn’t exist,’ according to astronomer and study co-author Vivien Parmentier of the Côte d’Azur Observatory in France.
‘The super-reflective cloud cover likely helped stop the planet from warming up too much and being stripped of its atmosphere,’ she said.
‘This is quite unique as all other planets at this temperature that are big enough to keep their atmosphere are too hot to form clouds and are thus as dark as charcoal.’
The planet’s diameter is about 4.7 times greater than Earth, and it orbits very close to its star, meaning its surface temperature is about 3,270°F (1,800°C) – hotter than molten lava
The planet also appears to be tidally locked to its star like the moon is to Earth, with a permanent day side facing the star and a permanent night side facing away.
All previously known planets that orbit their stars in less than one Earth day were either ‘hot Jupiters’ or rocky planets smaller than Earth and lacking an atmosphere.
The researchers are pondering whether LTT9779b, classified as an ‘ultra-hot Neptune,’ perhaps began as a gas giant, only to lose most of its atmosphere, or whether it started out at its current size.
More than 5,000 planets beyond our solar system have been discovered, many with traits vastly different than our solar system’s eight planets.
With increasingly capable instruments coming online – the James Webb Space Telescope became operational last year and the Extremely Large Telescope is under construction in Chile – more discoveries await.
‘The diversity of exoplanets is stunning,’ Ms Parmentier said, ‘and we have just scratched the surface.’
CHEOPS: A MISSION TO CHARACTERISE KNOWN EXOPLANETS
Cheops is the shortened name for ESA’s CHaracterising ExOPlanet Satellite mission.
It is the first mission dedicated to studying bright, nearby stars that are already known to host exoplanets.
It will make high-precision observations of the planet’s size as it passes in front of its host star.
It will focus on planets in the super-Earth to Neptune size range, with its data enabling the bulk density of the planets to be derived.
Cheops is the first small, or S-class, mission in ESA’s science programme.
It is a partnership between ESA and Switzerland, with a dedicated Consortium led by the University of Bern, and with important contributions from 10 other ESA Member States.
The first planet studied by Cheops was WASP-189b – an ultra hot Jupiter planet orbiting its star every three days.
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