What NASA is playing with the first images of the James Webb telescope

The James Webb Telescope complements the work of the Hubble Telescope, a veteran that investigates the visible and ultraviolet.

Ruth Lazkoz

RUTH LAZKOZ Professor of Theoretical Physics, University of the Basque Country / Euskal Herriko Unibertsitatea

Society may wonder why it is worth spending 100 billion euros on a telescope 50 times more expensive than its predecessor, Hubble. His first photographs have the answer.

The spy that emerged from the cold

Making convincing arguments for the usefulness of science is a juggling show, and one small mistake would land my little balls on the floor. Perhaps I dare to become vindictive before the intoxication of the show that the JWST promises to offer.

But a purely scientific argument is enough for now to be able to assess the value that his impressive images will have.

Putting a telescope in space is very expensive, of course. But why so far? Simply because it allows to optimize its operation in the range of infrared radiation. With this, the James Webb telescope complements the work of the Hubble telescope, a veteran that investigates the visible and ultraviolet.

This is a discard image of the James Webb, obtained by a Canadian instrument that is not dedicated to taking photos, it is in charge of choosing the field that Webb should aim at. However, that discard already offered the deepest picture of the universe ever taken. /

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The astronomical signals that reach us from space are a scarce commodity. And therefore it is convenient to get rid of the competitors. Water molecules in the atmosphere are very avid for infrared waves. On the other hand, in the depth and cold of space, the detectors get rid of that annoyance. And the same happens with unwanted heating caused by the parts of the instrument itself. This is achieved with a complicated device called an acoustic cooler.

That key piece of the JWST uses the Joule-Thomson effect, according to which a gas cools when the pressure on it decreases. Little did these two pioneers know how far their enthusiasm for basic physics would go. This gives us an idea that it is possible that many advances brought about by the most fundamental research also reach the confines of knowledge and the universe itself.

The technology developed for James Webb has already reached hospitals

So far the challenge of avoiding unwanted absorptions to obtain more precise and powerful signals. In reality, this is only a small aspect of the enormous degree of complexity of the challenges facing the JWST. And only by taking this into account will we be able to assess the cutting edge of science and technology that involves its development and exploitation. Suffice it to mention that a technology designed to calibrate your mirrors has been successfully transferred to ophthalmic laser surgery. And there are already tens of thousands of patients whose cornea has been operated on thanks to this transformative advance.

But enough of pamphlets! We better make poetry.

SMACS 0723 is a cluster of massive galaxies that magnify the light in the foreground and distort it for objects behind them, which will allow deep-field views of extremely distant galaxies and faint ones. Tomorrow we will see what James Webb has seen in this fabulous region of space. /

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Basic science in deep space

Stealing the concept from "The Little Prince", the James Webb telescope is the new heart of that living thing we call astronomy. This new instrument will allow us to see what is essential, what is invisible to the eye, the universe in infrared. Detecting and understanding the waves in this region of the universe is part of the intertwined history of astronomy and technology. Not surprisingly, they were predicted by Emile du Châtelet, the most illustrious pioneer of women in physics. Nor is it that they were discovered by one of the most distinguished astronomers in history, William Herschel. And in his honor a telescope was named that has more rudimentary cooling systems than James Webb.

It is also not surprising that the precursor to infrared thermometers made fashionable by the pandemic was invented for use in astronomy. This device, called a tasimeter, was created by Thomas Edison to detect temperature changes in the solar corona amplified during an eclipse.

The James Webb telescope takes over from all that discreet and stubborn science. And he promises to unlock some precious secrets of the universe thanks to his exquisite depth of field.

James Webb has taken pictures with a cosmic "magnifying glass"

We can think of James Webb as a bucket capable of collecting light. And it collects much more light than any space telescope to date. It is, so to speak, an eye with a larger pupil, only it is not a hole, but a meeting of mirrors. Thus, according to NASA, it has been able to obtain spectacular images produced by the SMACS 0723 gravitational lens system. This set of massive clusters of galaxies takes advantage of the curvature of space-time by magnifying the light of faint and distant galaxies located behind the. Thanks to this, we hope that it will give us the deepest look at the universe ever made.

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The stuff stars are made of

But let's get back to its capabilities in the infrared range. This particular telescope will investigate regions of the universe rich in cosmic dust, a compound of particles smaller than 100 microns. This is just on the order of the wavelength of infrared radiation, and thus can easily pass through cosmic dust clouds. Interestingly, this raw material is the substance that gives rise to stars. That is, it is significantly abundant in the regions where stars form. In soccer terms, they are something like the Farmhouse of the Universe. In fact, the embryonic stars remain for a time inside a chrysalis of dust.

However, in the universe we find cosmic dust clouds in very different sizes. For example, planetary nebulae are small and often surround dying stars. That is the case of the “Eight bursts” nebula, also the protagonist of the first collection of images that we will see through the eyes of James Webb. Interpretation of it is expected to lead to a better understanding of stellar evolution.

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And in the future?

We've hinted at the offerings to science this unique telescope will make, but much more awaits. For example, it is believed that it will be a key player in adjusting the current rate of expansion of the universe. Specifically, it will make it possible to make the necessary distance measurements more precise using red giant stars. One of the keys is that the uncertainty in the physics of these arbiters between local and distant measurements of the value of the Hubble constant is smaller in the infrared. This is because the emission in this range does not depend so much on its age or its metallic composition.

So many promises make us feel that we are going to have to find a vaccine for the Stendhal syndrome that each collection of images from the James Webb telescope will cause us. And perhaps what we as a community can aspire to is that this sustains vocations that can take full advantage of so much knowledge.

This article has been published in
'The conversation'.

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