James Webb Opens a New Age of Images

Nébuleuse de la Carène James Webb

The James Webb space telescope is getting to work and its first images, as well as its first spectral analysis, were revealed to the whole world.

The entire international scientific community has stars in its eyes. The wait has been long, the launch was postponed for eight years, but finally the first “scientific” images captured by the instruments of the James Webb space telescope are there, and they reveal a wealth of details the likes of which we have not seen for almost thirty years, when its predecessor, the Hubble space telescope, once its vision was corrected, started its long career of discoveries.

NASA, the European Space Agency (ESA), the Canadian Space Agency and the Space Telescope Science Institute had promised five images, but there are more, because four of the five views were in fact observed by each of several instruments, revealing the incredible capabilities of the new astronomical observatory.

Distant Galaxies

Revealed yesterday by the White House, the image of the distant background around the galactic cluster SMACS 0723 took only one day of observation for James Webb when it would have taken weeks for Hubble to achieve the same result. We can distinguish the effects of the gravitational lens of the cluster deflecting the light coming from galaxies behind it, which makes them appear as curved spots.

The SPACS 0723 galactic cluster, seen by the instruments MIRI (left) and NIRCam (right) on the James Webb space telescope.

The SPACS 0723 galactic cluster, seen by the instruments MIRI (left) and NIRCam (right) on the James Webb space telescope.

What Joe Biden did not show us is that this same background was observed in two infrared ranges: medium infrared by the Euro-American instrument MIRI (Mid Infrared Instrument) and near infrared by the American instrument NIRCam (Near-Infrared Camera).

Another amazing view, that of Stephan’s Quintet, in the Pegasus constellation. In reality, four of these galaxies, which interact and are deformed by tidal effects, are located about 340 million light years from our Milky Way, while the fifth, ten times closer, is only associated with them by chance of the perspective.

The first image, in near and medium infrared, is a mosaic made up of 1,000 images totalling more than 150 megapixels, and the internal structure of these galaxies appears in unequalled detail.

Mosaic of images of Stephan's Quintet in near and medium infrared, viewed by James Webb.

Mosaic of images of Stephan’s Quintet in near and medium infrared, viewed by James Webb.

A second mosaic, from views taken by MIRI in medium infrared alone, allows us to see even more clearly the internal structures of these galaxies through the dust clouds.

Stephan's Quintet in medium infrared, seen by James Webb's MIRI instrument.

Stephan’s Quintet in medium infrared, seen by James Webb’s MIRI instrument.

Nebulae and Star Nurseries

Closer to us, James Webb has once more demonstrated the complementarity of the fields covered by its instruments, pointing them at the Southern Ring nebula, in the Vela constellation. This planetary nebula – so called as it could be confused with a planet – is in reality an expanding gas cloud around a pair of stars, one of which is a white dwarf, which has cast off its outer layers and the other could explode in its turn, creating a new nebula inside the first. Its diameter is almost half a light year and it is about 2,000 light-years away.

The Southern Ring Nebula (NGC 3132).

The Southern Ring Nebula (NGC 3132).

On the left, the image from the NIRCam instrument in near infrared shows more clearly the dust and gases constituting the nebula, while on the right the same view, by the MIRI instrument in medium infrared, allows us to separate the stars and distinguish the internal structure of the nebula. In thousands of years, these delicate gaseous layers will dissipate into surrounding space.

Another major southern hemisphere nebula, the Carina nebula, in the constellation of the same name, is one of biggest and brightest in the sky. Located about 7,600 light-years away, this is a nursery for stars and for the first time, the James Webb space telescope allows us to discover its stars being formed, hidden behind what look like cliffs of dust and gas.

The Carina nebula, one of the biggest in the southern sky, revealed in detail by the James Webb space telescope.

The Carina nebula, one of the biggest in the southern sky, revealed in detail by the James Webb space telescope.

A second combined view  by Webb’s NIRCam and MIRI instruments allows us to zoom in on this nursery. In near infrared, we see hundreds of stars and galaxies in the background, while medium infrared reveals dusty discs forming planets (in red and pink) around young stars.

A close-up of the nursery of stars and the protoplanetary discs in the Carina nebula.

A close-up of the nursery of stars and the protoplanetary discs in the Carina nebula.

The Atmosphere of An Exoplanet

Not all the observations of James Webb can be as spectacular and colourful as the first images revealed on 12 July. The colours we are presented with are only there to translate images which we could not perceive, since we cannot see infrared, into images we can understand.

But the scientific importance is obvious, as is reflected by this other measure revealed among the first results of James Webb’s observations: the spectral analysis of light coming from an exoplanet, one of the first to have been discovered in 2014, WASP-96b. This gas giant, half as massive as Jupiter, is located almost 1,150 light-years away. Very close to its star, its orbit lasts almost 3.4 days.

Spectre WASP-96b James Webb

By breaking down the light from this very hot planet (more than 1000ºC), it was possible to obtain the most detailed spectral analysis of an exoplanet to date. The Canadian instrument NIRISS (Near Infrared Imager and Slitless Spectrograph) was able to identify the spectral signature of water, as well as indications of the presence of clouds which we thought until now did not exist on this exoplanet.

What other surprises will the next observations of the James Webb Space Telescope (JWST) have in store for us? Thanks to the precision of its insertion to orbit by Ariane 5 on 25 December, we may have a twenty-year mission to find out.