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Benoit Gougeon, Université de Montréal, Artistic rendition of the exoplanet TOI-1452 b |
Astronomers have discovered what they believe could be a real-life "water world" – a planet completely covered by ocean.
Orbiting a star some 100 light years from Earth, the planet
is in the so-called "Goldilocks zone" or "habitable zone” where
its temperature would be just right for liquid water to exist on the surface.
Just like Earth, it would retain its liquid water, as the
distance from its star means it isn’t too hot or too cold.
Named TOI-1452 b, the planet is slightly greater in size and
mass than Earth, but due to its lower density compared to Earth, scientists
think it may be covered by a thick layer of water.
Ocean planets are of particular interest to astronomers and
space enthusiasts alike, as they are thought to be strong candidates for
planets where life could originate or survive.
'Best ocean planet candidate'
Astronomers working on the study have called TOI-1452 b one
of the best ocean planet candidates discovered so far.
It was first spotted by NASA’s space telescope the
Transiting Exoplanet Survey Satellite (TESS), which surveys the entire sky to
find exoplanets around nearby bright stars.
TESS saw a slight decrease in brightness of a star in a
binary star system every 11 days, with astronomers predicting from this data a
planet about 70 per cent larger than Earth.
Astronomers from the Université de Montréal conducted
follow-up observations from a telescope on the ground to confirm the planet
type and its characteristics.
"This was no routine check," said Charles Cadieux,
a PhD student at the Université de Montréal and member of the Institute for
Research on Exoplanets.
"We had to make sure the signal detected by TESS was
really caused by an exoplanet circling TOI-1452, the largest of the two stars
in that binary system".
To work out the mass of the planet, observations were taken
with an infrared spectrum telescope, the Canada-France-Hawaii Telescope in
Hawai’i.
With more than 50 hours of observation, they estimated the
planet’s mass at nearly five times that of Earth.
"TOI-1452 b is one of the best candidates for an ocean
planet that we have found to date," Cadieux said.
"Its radius and mass suggest a much lower density than
what one would expect for a planet that is basically made up of metal and rock,
like Earth".
A prime target for the Webb Telescope
TOI-1452 b is thought to be rocky like Earth, but its
lower-than-expected density is believed to be due to a much larger quantity of
water than what we have on Earth.
While 70 per cent of planet Earth’s surface is covered in
water, water actually makes up less than 1 per cent of our planet’s mass.
The astronomers' analysis found as much as 30 per cent of
TOI-1452 b’s mass may be made up of water.
This is a proportion similar to some of the moons found in
our Solar System, such as Ganymede and Callisto of Jupiter, and Titan and
Enceladus of Saturn.
Publishing their findings in The Astronomical Journal, the
team is already planning follow-up studies with the most powerful telescope in
history.
The newly-launched James Webb Space Telescope (JWST) is in
high demand, and the team behind the TOI-1452 b discovery is already planning
to book some time to study their exoplanet.
It is close enough to Earth to allow astronomers to study its atmosphere, and it is also in a region of the sky that the JWST can observe all year round.
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