Stunning new Webb images: baby stars, colliding galaxies and hot exoplanets

2022-07-12

The views of the Universe just keep getting better. NASA’s US$10-billion James Webb Space Telescope released four new scientific images on 12 July, including newborn stars sparkling through dramatic ‘cliffs’ of gas, and galaxies interacting in an intricate cosmic dance. A day earlier, astronomers had marvelled at its very first image, a mind-boggling deep dive into the distant Universe.

Webb observes the cosmos in infrared wavelengths, which gives it a different view from that of many other observatories, such as the Hubble Space Telescope. Webb’s 6.5-metre-wide mirror is the largest ever launched into space, and the combination of the large mirror and its infrared detection capabilities allow Webb an unprecedented view of many astronomical phenomena.

These include stars and shock waves generated by collisions in a group of five galaxies known as Stephan’s Quintet, 90 million parsecs away in the constellation Pegasus. The images that Webb collected of this galactic grouping reveal millions of young stars forming as gas and dust collide, as well as sweeping tails left by one of the galaxies, NGC 7318B, as it storms its way through the cluster. “It really shows the type of interaction that drives the evolution of galaxies,” says Giovanna Giardino, an astronomer with the European Space Agency.

And that’s not all. “For me, what was surprising about Stephan’s Quintet was just how many galaxies are in the background,” says Jane Rigby, Webb’s operations project scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland.

Other cosmic action appears in a new Webb image of the Carina Nebula, a star-forming region around 2,300 parsecs away. Big, hot stars at the nebula’s centre blast it with radiation, which carves out a gaseous cavity, ringed with dramatic peaks and valleys and dubbed the Cosmic Cliffs. Webb’s infrared capabilities permitted it to peer through dust that often cloaks this view for other telescopes. The observatory also revealed brilliant pinpricks of light in the nebula, marking newborn stars. “There’s just so much going on here — it’s so beautiful,” says Amber Straughn, an astrophysicist at Goddard.

On the opposite end of the stellar lifecycle is the Southern Ring Nebula, a glowing shell of gas and dust that was ejected by a star near the end of its life. Located around 770 parsecs away in the constellation Vela, the nebula displays rings of material, each ejected during a particular episode of the star’s death throes. “You see what the star did just before it created this planetary nebula,” says Klaus Pontoppidan, Webb’s project scientist at the Space Telescope Science Institute in Baltimore, Maryland. “I find it fascinating because it’s like geological layers, and you can see the history of its last moments.”

Webb’s high resolution enabled it to pick out intricate detail in these shells, as well as revealing a second star that orbits the main one. Together, those stars light the surrounding nebula like the Sun shining through patchy clouds.

Perhaps the least visually striking, but most scientifically compelling, image of NASA’s release is a chemical analysis, or spectrum, of the atmosphere of a distant planet known as WASP-96b. This planet is around half the mass of Jupiter but orbits its star in just 3.5 days, meaning that its surface is extremely hot. Webb observed the planet as it passed across the face of its star, such that the starlight travelled through the planet’s atmosphere and enabled scientists to chemically analyse it. They spotted the fingerprint of water in the atmosphere of WASP-96b, suggesting that it is a truly steamy place.

The spectrum is “just spectacular”, says Christopher Evans, the European Space Agency’s Webb project scientist. “People have been trying to do [spectroscopy] from the ground for years … and suddenly it’s just right there, and that’s the first go.”

It is the first of many exoplanet spectra that Webb will gather — in a research field that did not even exist when the telescope was being dreamed up, before any planets were known beyond the Solar System. And yet exoplanets now promise to be one of Webb’s most significant areas of discovery. Studies of spectra from these planetary bodies can reveal how life-friendly other worlds might be. “We can use this tool to see something, because people want to know, when are we gonna see another Earth?” says John Mather, Webb’s senior project scientist at Goddard.

All four of the telescope’s instruments have been fully commissioned and are now doing science. Astronomers are thrilled to have this new and hugely capable observatory, which promises to enable discoveries across a wide range of astronomical phenomena. “We’ve got this humongous laboratory to learn about different aspects and different areas of the Universe,” says Hannah Wakeford, an astronomer at the University of Bristol, UK.

Webb is a collaboration between NASA, the European Space Agency and the Canadian Space Agency. It launched in December after more than two decades of development, and observes the Universe from a spot in space on the other side of the Moon, 1.5 million kilometres from Earth.

Nature, 12 July 2022
; https://nature.com