James-Webb: the first images open a new era of astronomy

Of them nebulaea group of galaxiesan exoplanet, a cluster of galaxies and a deep field are therefore the first images and spectra of the James-Webb space telescope which were presented and kick off the scientific operations. This new era that is dawning for astronomy has been unanimously welcomed by the scientific community, which expects significant advances in many fields.

James-Webb is the result of an international partnership between the NasaI’ESA and the Canadian Space Agency (CSA). ” These first images and spectra of Webb are a huge celebration of the international collaboration that made this ambitious mission possiblesaid Josef Aschbacher, Director General of ESA. I want to thank everyone involved in commissioning this magnificent telescope and releasing these incredible first images of Webb – you made this historic day a reality. In addition to launch services, ESA has contributed two of the four science instruments (the NIRSpec instrument and the optical assembly of the Miri instrument), and is providing the personnel necessary for mission operations at a total cost of 700 million euros. In return for this investment, Europe has a guaranteed minimum of 15% of the observation time but, for the first observation cycle, due to the quality of the observation requests from the astronomers Europeans, the share allocated to European scientists is around 30%.

The SMACS 0723 deep field to the edge of the universe

The first image to be unveiled is the deep field SMACS 0723 whose careful observation tells a story of theUniverse at all ages, beginning 13.8 billion years ago. This deep field uses the gravitational lens of a cluster of galaxies to reveal some of the most distant galaxies ever detected. With an exposure time of just 12.5 hours, this image only scratches the surface of Webb’s abilities in studying deep fields. Some of the objects visible in this image are more than 13 billion years old, confirmed Pierre Ferruit, JWST program manager at ESA. They formed only a few hundred million years after the big Bang. The rapid reading of the data of this image does not make it possible to date with certainty objects formed only a few hundred million years ago after the Big Bang. Further analysis of the image is necessary to have a precise dating. Other deep fields, with longer exposure times, will be produced in the coming months, some of which are identical to those ofHubble and everything suggests that James-Webb will discover galaxies only a hundred million years old.

A planetary nebula in our neighborhood

From birth to death of a planetary nebulaJames-Webb can explore dusts and gas of the stars aging that could one day become a new star or planet. It is worth remembering that the NIRCam and Miri instruments complement each other very well. The first will provide images with a very good level of detail and a very fine rendering. It is well suited for observing hot objects like galaxies. Conversely, he will see the dust less well, colder. As for Miri, her main interest is that the stars in her field of vision tend to disappear. This instrument is therefore very useful for observing very cold objects, including dust, and finding the light galaxies that are so old that they no longer emit in the visible.

A spectrum that changes the era of planetary spectroscopy

James-Webb detected molecules of water on an exoplanet which obviously does not constitute an indication of extraterrestrial life. The interest of this spectrum is to demonstrate a large part of the remarkable capabilities of the NIRISS instrument. Remarkable because it is the spectrum in theinfrared of an exoplanet the most detailed ever collected, the first spectrum that includes wavelengths greater than 1.6 micron to one resolution and accuracy, and the first to cover the entire wavelength range from 0.6 microns (visible red light) to 2.8 microns (near infrared) in a single shot.

James-Webb will now study hundreds of other systems to figure out what the others are made of atmospheres planetary. Among the observation campaigns already approved, mention should be made of the detailed characterization of large organic molecules in the orion nebula, the atmosphere of brown dwarfs and the observation of several planetary systems including that of Trappist-1b. The little Trappist star-1at 40 light years of us, has this particularity that it has a fascinating planetary system: seven earth-like planets, three of which have orbits included between those of Venus and March.

The formation of stars, a strong theme of James-Webb

Stars derive from and contribute to massive amounts of gas and dust, swirling around galaxies. Dust evolves over time, and Webb can study nearby, dynamically interacting galaxies to see dust in action. Now scientists can get a rare glimpse, in unprecedented detail, of how interacting galaxies trigger star formation within each other and how the gas in these galaxies is affected. To get an accurate idea of ​​the performance of the James-Webb, download the images from the European Space Agency’s JWST site by clicking here and wander through the image.

The complementarity of instruments, one of the strengths of James-Webb

By observing this region of star formation and others like it, scientists can, thanks to James-Webb, see newly formed stars and study the gas and dust that made them.

The bottom image is a composite made from images acquired by the near-infrared instruments (NIRCam) and the mid-infrared instrument (Miri). By merging the data from the two instruments, details are revealed.

Comparing James-Webb images with those from Hubble isn’t as simple as it sounds

The comparison of the James-Webb images with those of Hubble still has limits due to the fact that the two space observatories do not observe at the same wavelengths and do not use the same colors. This explains why certain objects are more present in the images of Webb, in particular the galaxies which emit in the red, than in images of Hubble.

You should also know that the most distant galaxies are not visible to Hubble because they are either shifted in the red, or located behind in the clouds very dense dust. Added to this is that Webb’s sensitivity is such that on all his images we will see galaxies in the background! So you have to be very careful when comparing them.