The greatest possibility for an ocean world with sloshing water so far
looks to be an exoplanet that is only 100 light-years away from Earth.
Its size and mass data indicate a density profile that is compatible with a
large, liquid ocean. Its name is TOI-1452b. Although they haven't definitely
discovered one, scientists think that planets like this are plausible.
The first findings are quite exciting, but further observations from the
James Webb Space Telescope are required to fully understand the exoplanet's
atmosphere and determine its composition.
Researchers from the University of Montreal in Canada, under the direction
of astronomer Charles Cadieux, present their findings in a study that
appears in The Astronomical Journal. "This work reports the discovery and
characterisation of the transiting temperate exoplanet TOI-1452b," they
write.
TOI-1452b is a viable contender for a water world based on the outcomes of
our interior modeling and the fact that the planet only experiences moderate
irradiation.
Even though TOI-1452b is quite close to the Solar System, it is simple to
see how it has escaped detection up to this point.
The exoplanet was discovered circling one of a pair of tiny, faint red
dwarfs that form a tight binary system and are only 97 astronomical units apart. The two stars seem to be one since they are so close together.
The TESS exoplanet-hunting telescope, however, is sensitive enough to have
found periodic, small dips in illumination that signify an object routinely
passing between us and its host star; these crossings over the star are
known as transits. At Canada's Mont Mégantic Observatory, the researchers
then developed their own very sensitive device that is likewise intended to
detect planetary transits.
Both telescopes' studies confirmed the existence of an exoplanet circling
one of the stars in the TOI-1452 pair.
The researchers were able to determine that the exoplanet is quite tiny,
measuring in at 1.672 times the size of Earth - what we refer to as a
super-Earth - by observing how much light the star emits and how much it
dims as the exoplanet passes in front.
With our somewhat sluggish 365-day orbit, its 11-day cycle around its star
looks absurdly near to us. The exoplanet, however, is right in the heart of
the star's temperate zone since the star is so cold and faint in comparison
to the Sun. The location is neither too far away from the star, where any
liquid water on its surface would freeze, nor too close, where the star's
heat would cause the water to evaporate.
The scientists then focused their attention on the star. They specifically
looked at its radial velocity, or how the exoplanet's gravitational pull
causes it to travel. As a result, the star shifts somewhat in its orbital
arrangement with TOI-1452b. This is because any two entities in a system
orbit a mutual center of gravity.
This motion is revealed by variations in the star's brightness, and even
better, astronomers can compute the mass of the orbiting matter by figuring
out how strong the motion is. Thus, they were able to calculate TOI-1452b's
mass to be 4.82 times that of the Earth.
And here is when things really start to get interesting.
You can determine the average density of an object after you know its size
and mass. The density of TOI-1452b is 5.6 grams per cubic centimeter, which
is quite near to the density of the Earth, which is 5.5 grams per cubic
centimeter. However, the researchers noted that a density close to that of
Earth for an object with larger mass suggests that the object is made of a
lighter substance.
According to Cadieux, TOI-1452b is one of the most promising prospects for
an ocean planet thus far. Its mass and radius point to a far lower density
than one might anticipate for a planet like Earth, which is mostly composed
of metal and rock.
They created a model of the exoplanet's innards and found that water may
make up as much as 30% of its mass.
That much of the wet stuff is a lot. The composition of TOI-1452b looks
more similar to that of the water moons Europa in orbit with Jupiter and
Enceladus in orbit with Saturn than that of Earth, where water makes up less
than 1% of the planet's mass.
However, it is hard to determine the precise composition of TOI-1452b based
solely on the measurements we have. In this situation, Webb is useful.
Do you recall how the exoplanet orbits its star in our direction? If an
atmosphere exists on the exoplanet, some of the star's light will pass
through it. Webb's sensitivity enables researchers to determine what's in
the exoplanet's atmosphere by detecting the difference in that light in
sufficient detail.
Webb is our greatest chance to find TOI-1452b if it is a water world.
To explain TOI-1452b, René Doyon of the University of Montreal's Department
of Astronomy states that "our studies with the Webb Telescope will be
vital." "We will schedule time on Webb as soon as we can to examine this
unusual and fascinating world," they said.
