An ocean world within reach by James-Webb


VS’is a timely discovery! An international team of researchers led by Quebecer Charles Cadieux, a doctoral student at the University of Montreal, and his research director, astrophysicist René Doyon, believe they have found an ocean world in orbit around a red dwarf in a binary star system relatively close to the Sun.

Discovered in the constellation of the Dragon, two years ago, thanks to the space telescope Tess (Transit Exoplanet Survey Satellite) of Nasa, this exoplanet baptized TOI-1452b would indeed be only a hundred light years from us. . Enough to make this rocky body possibly covered with a thick layer of liquid water, so precious to life, a target of choice for the new James-Webb space telescope.

A very light super-Earth

Indeed, if the authors of the new study published in The Astronomical Journal in September convinced themselves that it was a vast and deep ocean, not at all by direct observation but by deductions and models. First, by analyzing data from Tess, who observed this planet as it transited in front of its star, they were able to find out its size: 70% larger than our planet. The super-Earth kind! They then set out to measure the other determining parameter thanks to which scientists manage to get an idea of ​​what exoplanets look like: their mass.

To do this, they used a new generation instrument called Spirou, for infrared spectropolarimeter, developed with French researchers from the University of Grenoble and mounted on the Canada-France-Hawaii telescope. A tandem that allowed them to use the other great technique for detecting exoplanets. The method of radial velocities which assumes that a planet revolving around its star pulls it into a circular motion and thus triggers small regular variations in its radial velocity (its velocity in a direction parallel to the Earth-star axis ). An influence that depends directly on its mass and therefore makes it possible to trace it back.

Our Neighborhood Ocean World

Result: TOI-1452b is almost five times more massive than Earth. Which, compared to its size, gives it a much lower density than what one would expect for a body composed mainly of metal and rock, like the Earth. Our beautiful blue planet which, although more than 70% covered by oceans, is only made up of one percent water! For TOI-1452b it could be more like 30%! But his case is not rare: there are other planets with this type of parameters in the universe. Except that they are further away. By observing TOI-1452b with James-Webb, which will give a real idea of ​​its chemical composition, we will finally be able to know if the models are correct and if these are indeed ocean worlds.

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From there to imagining that they can harbor life, there is only one step which will still require examining other parameters, in particular the nature of their host star. In the case of TOI-1452b, this element is not totally favorable since, as mentioned above, it orbits around a red dwarf of a binary system, a type of star that is small, cold and famous for copiously watering their not quite friendly radiation environment…

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