an astrophysicist tells us about his experience with the James Webb

Olivier Berné and his colleagues recently presented us with superb images of the Orion nebulae taken using the James Webb Space Telescope; he agreed to tell us the story of this wonderful sighting.

On September 12, the James Webb Space Telescope made a superb gift to astronomers and star lovers by unveiling its first images of the Orion Nebula. And it turns out that this exceptional observation, we owe it to a French team based at the Institute for Research in Astrophysics and Planetology (IRAP), a structure that depends on the CNRS; astrophysicist Olivier Berné, one of the great artisans of this work, has agreed to tell us about the rediscovery of this iconic piece of sky.

It all started in 2017 with a call for projects launched by NASA, the US space agency that spearheaded the construction of the telescope. At the time, the James Webb was still very far from being operational. But the staff of the agency was already in the ranks, in the process of preparing the ground so that the machine could start at top speed.

She wanted to mark the occasion with the scientific community and the general public; she therefore asked astronomers to offer her programs that are both ambitious and emblematic, all centered around very promising themes of astrophysics. The goal: to show what James Webb has in his stomach to the whole planet.

years of preparation

Information that did not fall on deaf ears. Because Olivier Berné and infrared telescopes is a love story that started a long time ago, and which followed him on the benches of the University of Toulouse 3; his thesis (defended in 2008 and available here) happens to be on the Spitzer Space Telescope, another important representative of this category. And in the conclusion, we even find an allusion to another familiar instrument

These two images of Orion by Spitzer (left) and Webb (right) allow us to appreciate the exceptional performance of the latter. © NASA / JPL-Caltech / ST Megeath / ESA /CSA / PDRs4All Team S. Fuenmayor

The James Webb Space Telescope will follow in 2013. With its huge segmented mirror 6.5 meters in diameter, optimized for infrared, this instrument will have incredible sensitivity “, can we read on the 167th page of the document. ” One of the most interesting topics with the JWST will be the study of protoplanetary disks with high spatial resolution. One can imagine that it will be possible to study the evolution of the infrared bands inside the disc “, he specified. And the least we can say is that history has proven him right down the line – except for the announced date!

Neither one nor two, his team therefore hastened to register on the list of suitors in the hope of concretizing this old romance. She proposed her great project of observing the Orion Nebula to NASA. And the case was apparently very strong, as it stood out among several dozen other top programs. Berné and his colleagues have earned their place on the list of 13 finalist teams who have won the long-awaited reward: a honeymoon with the new darling of astrophysics.

An experience that the interested party readily describes as ” pridean honor “, and “ a big chance “. However, he had to fret for a while while waiting for the James Webb to take up position on its perch, at the Lagrange L2 point of the Earth-Sun system.

An instrument even more exceptional than expected

This interminable wait ended at the beginning of the year when the telescope, now comfortably installed in its orbit, finished aligning its mirrors and calibrating its instruments. When their turn finally came, Berné and his colleagues were able to achieve the observation they had dreamed of for so long by pointing the Webb’s lens right at the Orion Nebula for about forty hours. ” We’ve been waiting for this mission for years. “, he explains.

© NASA / ESA /CSA / PDRs4All Team S. Fuenmayor

When the pictures came in the night, we rushed to the lab “, he remembers. With his colleagues, they were able to follow almost live the arrival of a digital gift package loaded with 60 GB. For the record, it was the processed and reduced version; the weight of the raw data, on the other hand, was more in TB.

Anyway, that’s when they first discovered the core of the Orion Nebula, before the images were colorized for public display. A moment that we imagine charged with emotions for the team, and a good opportunity to finally become fully aware of the phenomenal capacities of the instrument.

At times like this, when we discover the first images of a program that we have been preparing for several years, we realize how lucky we are to be able to use the most extraordinary telescope ever created by humanity, and point it in the direction you want to point it! smiles Olivier Berné.

We have the best spatial resolutions, the best spectral resolutions, the largest field of view that we have ever had in a single instrument… “, he lists. ” It combines all the best telescopes I’ve used in my career. »

A mountain of data to dissect

A press release later, the public was treated to new images of this iconic nebula. But for the researchers, the work had only just begun. Because it’s not not just for the pleasure of the eyes that the new king of telescopes draws the portrait to these objects thanks to his crown of reflectors; the priority objective remains to produce high-flying science. And that’s what Olivier Berné’s team is working on right now.


Once the data was retrieved, they embarked on an interpretation phase still in progress at the time these lines are written. And they are far from finished; nothing surprising given the density of information reported by the JWST. Especially since the team has not even recovered all the data associated with this observation yet.

We have more images coming Berné promises. ” We also have spectroscopy to do over the coming weeks and months. This part has not yet been scheduled “, he specifies. ” For now, we are looking at all the data we have available and discussing what we are going to come out with in terms of scientific results as soon as possible. “, he engages.

After the observation, place to the publication

And without going so far as to talk about a race against the clock, Olivier Berné and his colleagues will actually not have to hang around. Indeed, even if they were the instigators of this project, they do not have the exclusive use of the data produced, far from it; the elements reported by the James Webb are systematically available in free access, including all those concerning the Orion Nebula.

© NASA / ESA /CSA / PDRs4All Team S. Fuenmayor

It is therefore not excluded that other researchers publish research articles before the IRAP troops. And getting out of the game could be a tad frustrating for this team, knowing how much effort it takes to get there. “ If other people come out with scientific results in our place… that’s fine, the main thing is that all of this is published », concedes Olivier Berné after a short hesitation.

He is a good player, and it is to his credit; but he also admits frankly that he and his colleagues are very keen to ensure the continuity of this work which is very close to their hearts. ” We would still like to be able to release these results ourselves “, he admits. ” The involvement in a project like that is such that there is necessarily a part of emotion that comes into play, that’s for sure. »

Something that defines humanity »

All that remains is to wait for these superb images to deliver their best-kept secrets, with all that this implies for astrophysicists… but also for the rest of the population. A contribution that Oliver Berné made a point of emphasizing by recalling that the mission of James Webb – to go back to the origins of the Universe – is not only a matter of raw science; one can even consider that his work also concerns the very essence of human nature.

He insists on the role of astrophysics, and more broadly of the sky, in the collective imagination; once embarked on our daily routine, it is easy to forget that the celestial vault is also a real window on the history of the Universe and of the little humans that we are.

© NASA / ESA /CSA / PDRs4All Team S. Fuenmayor

This question of origins is a question that has animated humanity since its beginnings and which, I think, is important. To go that far in the search for its origins by making extremely complex, extremely expensive things, to try to answer these questions… in my opinion, it is something that defines humanity. »

This perspective, I think it is important in the current context where we observe profound changes, for example in the climate. I think it also allows you to put certain things into perspective, and it’s very important to appreciate our smallness in the universe and to learn to be humble about a certain number of things. »

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