Scientists have discovered an exoplanet located 90 light-years from Earth with an intriguing atmosphere, one that could contain clouds of water.
Exoplanets are planets located outside of our solar system. This exoplanet, called TOI-1231 b, completes a full orbit around its star every 24 Earth days.
It orbits a red or M-type dwarf star, known as NLTT 24399, which is smaller and dimmer than stars like our sun.
The planet’s discovery was detailed in a new study to be published in a future issue of The Astronomical Journal.
“Although TOI 1231 b is eight times closer to its star than Earth is to the Sun, its temperature is similar to that of Earth, thanks to its colder and less bright host star,” said study co-author Diana Dragomir, assistant. a professor in the department of physics and astronomy at the University of New Mexico, said in a statement.
“However, the planet itself is actually larger than Earth and slightly smaller than Neptune; we could call it subneptune.”
Why this exoplanet could have clouds
The researchers were able to determine the radius and mass of the planet, which helped them calculate its density and infer its composition.
The exoplanet has a low density, suggesting that it is a gaseous planet rather than a rocky one like Earth, but scientists still do not know for sure the composition of the planet or its atmosphere.
“TOI1231b could have a large hydrogen or hydrogen-helium atmosphere, or a denser water vapor atmosphere,” said Dragomir.
“Each of these would point to a different origin, allowing astronomers to understand whether and how planets form differently around M dwarfs, compared to planets around our Sun, for example.”
Researchers believe TOI-1231 b has an average temperature of 60 degrees Celsius, making it one of the coldest small exoplanets available for future studies of its atmosphere.
“Compared to most of the transiting planets detected so far, which often have scorching temperatures of several hundred to thousands of degrees, TOI-1231 b is positively icy,” Ms Burt said.
The colder the exoplanet is, the more likely it is to have clouds in its atmosphere.
The equally small exoplanet K2-18 b, discovered in 2015, was recently observed in more detail, and the researchers found evidence of water in its atmosphere.
“TOI-1231 b is one of the only other planets we know of in a similar size and temperature range, so future observations of this new planet will allow us to determine how common (or rare) it is for water clouds to form. around these temperate worlds, “Burt said in a statement.
This makes TOI-1231 b the perfect candidate for observations by the Hubble Space Telescope, or the James Webb Space Telescope, which is scheduled to launch in October.
Webb will have the ability to observe the atmospheres of exoplanets and help determine their composition.
And Hubble is scheduled to observe the exoplanet later this month.
The search for exoplanets
Burt, Dragomir and their colleagues discovered the planet using data from NASA’s Transiting Exoplanet Reconnaissance Satellite, or TESS.
The Planet Search Satellite, launched in 2018, observes different areas of the sky for 28 days at a time.
So far, TESS has helped scientists find large and small exoplanets orbiting stars like our sun, as well as smaller M-dwarf stars.
These tiny stars are common in the Milky Way.
When a planet crosses in front of its star during orbit, it blocks a certain amount of light.
This is called a transit, and it’s a way that astronomers search for exoplanets using missions like TESS.
Since M-dwarf stars are smaller, the amount of light blocked by an orbiting planet is greater, making the transit more detectable.
Scientists look for at least two transits before determining if they have found an exoplanet candidate.
Follow-up observations were made using the Planet Finder Spectrograph on the Magellan Clay telescope at Las Campanas Observatory in Chile.
“One of the most intriguing results of the last two decades of exoplanet science is that, so far, none of the new planetary systems we have discovered looks anything like our own solar system,” said Burt.
“This new planet that we have discovered is still strange, but it is one step closer to looking a bit like the planets in our neighborhood.”
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