A busy science mission for the James Webb Space Telescope


A busy science mission for the James Webb Space Telescope

One ​​of the first images captured by the James Webb Space Telescope was shown during a press conference with United States President Joe Biden.

The James Webb Space Telescope revealed its first images of the cosmos earlier this week, but its work has only just begun. Scientists around the world have already booked observing time with this impressive new tool, and their cosmic targets are as diverse as they are fascinating.

First galaxies, distant stars, exoplanets… the program for the first year of observation has been determined in advance by a committee of experts, and has been for over a year already.

Anyone can, in theory, use this telescope for their research – as long as they know what to observe and have their proposal selected.

Among the lucky ones, Olivia Lim, doctoral student at the University of Montreal, who is only 25 years old. I'm lucky enough to use this telescope when I wasn't even born when people started talking about it, she told AFP.

Its goal: to observe planets revolving around a star named Trappist-1. The system has seven planets in all, similar in size to Earth. They are so close to each other that from the surface of one, you could see the others appearing clearly in the sky.

The Trappist-1 system is unique, explains the young woman. All, or almost all, conditions there are favorable for the search for life outside our solar system.

They are indeed rocky planets (and not carbonated). In addition, three are in the so-called habitable zone, that is, neither too close nor too far from their star, offering adequate temperatures for liquid water to exist on their surface. /p>

Other advantages: they are located only 39 light years away. And, above all, we can see them pass in front of their star from our point of view (we say that they transit their star).

This is what allows to study them, by observing the drop in luminosity that their passage in front of the star produces. Several of these transits are expected to be observed as early as this month.

It is not yet known whether these planets have an atmosphere, but Olivia Lim seeks to find out. If so, light passing through the atmosphere will be filtered by the molecules within.

The grand prize would be to detect the presence of water vapour, CO2 or ozone, specifically sought after.

Trappist- 1 is such a prime target that several other science teams have also been granted time to observe them.

Finding traces of life there, if they exist, will still take time, according to Olivia Lim. But all that we are doing this year are really important steps to reach this ultimate goal, underlines the researcher.

In addition to exoplanets, one another great promise of James Webb is the exploration of the early ages of the Universe.

How? Because the farther you look, the longer you see. Sunlight, for example, takes eight minutes to reach us, so we see it as it was eight minutes ago. Thus, by looking as far as possible, one can perceive the light as emitted billions of years ago.

Astronomers have so far succeeded to go back 97% of the time to the big bang, which occurred 13.8 billion years ago.

But the most distant galaxies don' appeared for the moment only in the form of tiny red spots, explained to AFP Dan Coe, astronomer at the Space Telescope Science Institute, responsible for James Webb's operations in Baltimore, near Washington.

The researcher has two upcoming observation programs: the first targeting one of the most distant galaxies known, MACS0647-JD, discovered in 2013, and the second focusing on Earendel, the most distant star ever detected, this year alone.

With James Webb, we are finally going to be able to see inside these galaxies, to see what they are made of, both in images and by spectroscopy, it is going to be incredible, he assured.


Spectroscopy makes it possible, through the analysis of the light captured, to determine the chemical properties of a distant object.

If recent galaxies can be elliptical or spiral, older ones were more irregular, notes Dan Coe.

And we don't yet know what the very first stars look like, which probably have began to form about a hundred million years after the big bang.

The theory is that these early so-called population III stars were far more massive than our Sun, and made only of hydrogen and helium. Their supernova explosion went on to help enrich the interstellar medium, leading to the formation of today's planets and stars.

Some doubt that & #x27;it is possible to see these stars. But that won't stop astronomers from continuing to try.


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