Pull to refresh

I’m in heaven

The James Webb Space Telescope opens for business

July 11, 2022

What looks much like craggy mountains on a moonlit evening is actually the edge of a nearby, young, star-forming region NGC 3324 in the Carina Nebula. Captured in infrared light by the Near-Infrared Camera (NIRCam) on NASA’s James Webb Space Telescope, this image reveals previously obscured areas of star birth.Called the Cosmic Cliffs, the region is actually the edge of a gigantic, gaseous cavity within NGC 3324, roughly 7,600 light-years away. The cavernous area has been carved from the nebula by the intense ultraviolet radiation and stellar winds from extremely massive, hot, young stars located in the center of the bubble, above the area shown in this image. The high-energy radiation from these stars is sculpting the nebula’s wall by slowly eroding it away. NIRCam – with its crisp resolution and unparalleled sensitivity – unveils hundreds of previously hidden stars, and even numerous background galaxies. Several prominent features in this image are described below.•The “steam” that appears to rise from the celestial “mountains” is actually hot, ionized gas and hot dust streaming away from the nebula due to intense, ultraviolet radiation. •Dramatic pillars rise above the glowing wall of gas, resisting the blistering ultraviolet radiation from the young stars.•Bubbles and cavities are being blown by the intense radiation and stellar winds of newborn stars.•Protostellar jets and outflows, which appear in gold, shoot from dust-enshrouded, nascent stars.•A “blow-out” erupts at the top-center of the ridge, spewing gas and dust into the interstellar medium. •An unusual “arch” appears, looking like a bent-over cylinder.This period of very early star formation is difficult to capture because, for an individual star, it lasts only about 50,000 to 100,000 years – but Webb’s extreme sensitivity and exquisite spatial resolution have chronicled this rare event.Located roughly 7,600 light-years away, NGC 3324 was first cat
As sites for celestial photoshoots go, the “Cosmic Cliffs” (above) were always going to be a safe bet. These stunning, textured peaks of dust and gas in the Carina nebula are light-years high. So the cliffs’ appearance this week at the release of the James Webb Space Telescope’s (jwst) first images was no great surprise. The jwst’s predecessor, the Hubble Space Telescope, snapped the same region in 2005.
The difference between these vistas could not be more striking. The jwst, the largest space telescope ever built, has already spotted baby stars among the peaks that no previous observatory could manage. This week’s snaps give just a hint of the thrilling programme of science to come.
The telescope was launched, after 11 years of delays and at a cost of $9.7bn, on Christmas Day 2021. Its ballooning budget, even when split between nasa and the space agencies of Europe and Canada, almost got it cancelled. But it was too big to be sunk. Before lift-off, Thomas Zurbuchen, nasa’s head of science, told The Economist that “The last thing we want to do is save a billion dollars and fail.”
Seven months into the mission, every aspect of launch, deployment and performance seems to have gone according to plan, if not better. As a result, astronomers now have the most powerful tool yet given them to scan the cosmos in infrared frequencies of light. That will let them study many things they have struggled to examine in the past—in particular, the formation of stars and planets, from the universe’s youth to the present day.
After its launch, the jwst manoeuvred its way to Lagrange 2, a point in space 1.5m km away where the gravitational fields of the Earth and the Sun conspire to create a gravity well. Here the alignment of the Earth and the Sun are such that the jwst’s shield can block illumination from both—a necessity, for the telescope’s infrared-detecting instruments need to be kept cold.
The jwst’s potential lies in a combination of its sheer size (its primary mirror, of gold-plated beryllium, is 6.8 metres across) and the cleverness of those four well-chilled detectors.
These are miri (which detects long infrared wavelengths), nirCam and nirSpec (which take images of and analyse short-wave infrared) and fgs/niriss (which studies bright targets such as nearby stars orbited by exoplanets).
The wavelengths examined by miri correspond to objects such as exoplanets with no internal source of heat, and hotter but more distant bodies whose light has been stretched from visibility into the infrared by the expansion of the universe.
Given that “farther away” also means “longer ago” in cosmic terms, this will enable it to spot signs of the cosmic dawn, the moment when the universe’s first stars ignited. A “deep-field” image also released this week (pictured above) is the first glimpse of that power; in it are features whose light set off more than 13bn years ago.
The infrared light that is the jwst‘s speciality penetrates dust clouds more successfully than visible light can, thus tearing away the veil from intriguing pockets of the sky where dust is coalescing into stars and planets—places such as the Cosmic Cliffs.
The bright star at the center of NGC 3132, while prominent when viewed by NASA’s Webb Telescope in near-infrared light, plays a supporting role in sculpting the surrounding nebula. A second star, barely visible at lower left along one of the bright star’s diffraction spikes, is the nebula’s source. It has ejected at least eight layers of gas and dust over thousands of years.But the bright central star visible here has helped “stir” the pot, changing the shape of this planetary nebula’s highly intricate rings by creating turbulence. The pair of stars are locked in a tight orbit, which leads the dimmer star to spray ejected material in a range of directions as they orbit one another, resulting in these jagged rings.Hundreds of straight, brightly-lit lines pierce through the rings of gas and dust. These “spotlights” emanate from the bright star and stream through holes in the nebula like sunlight through gaps in a cloud.But not all of the starlight can escape. The density of the central region, set off in teal, is reflected by how transparent or opaque it is. Areas that are a deeper teal indicate that the gas and dust are denser – and light is unable to break free.Data from Webb’s Near-Infrared Camera (NIRCam) were used to make this extremely detailed image. It is teeming with scientific information – and research will begin following its release.This is not only a crisp image of a planetary nebula – it also shows us objects in the vast distances of space behind it. The transparent red sections of the planetary nebula – and all the areas outside it – are filled with distant galaxies. Look for the bright angled line at the upper left. It is not starlight – it is a faraway galaxy seen edge-on. Distant spirals, of many shapes and colors, also dot the scene. Those that are farthest away – or very dusty – are small and red.For a full array of Webb’s first images and spectra, including downloadable files, please visit: https:
The accuracy of the jwst’s launch meant midcourse corrections to put the telescope in orbit used less fuel than budgeted. That leaves more for the small adjustments needed to keep the instrument on station. Given that station-keeping is the main constraint on mission length, that matters. The initial goal was ten years, but nasa now reckons it can keep the telescope in place for 20. On top of this, all four instruments appear more sensitive than modelled, and thus capable of collecting 10-20% more photons than expected.
A transmission spectrum made from a single observation using Webb’s Near-Infrared Imager and Slitless Spectrograph (NIRISS) reveals atmospheric characteristics of the hot gas giant exoplanet WASP-96 b. A transmission spectrum is made by comparing starlight filtered through a planet’s atmosphere as it moves across the star, to the unfiltered starlight detected when the planet is beside the star. Each of the 141 data points (white circles) on this graph represents the amount of a specific wavelength of light that is blocked by the planet and absorbed by its atmosphere. In this observation, the wavelengths detected by NIRISS range from 0.6 microns (red) to 2.8 microns (in the near-infrared). The amount of starlight blocked ranges from about 13,600 parts per million (1.36 percent) to 14,700 parts per million (1.47 percent).Researchers are able to detect and measure the abundances of key gases in a planet’s atmosphere based on the absorption pattern – the locations and heights of peaks on the graph: each gas has a characteristic set of wavelengths that it absorbs. The temperature of the atmosphere can be calculated based in part on the height of the peaks: a hotter planet has taller peaks. Other characteristics, like the presence of haze and clouds, can be inferred based on the overall shape of different portions of the spectrum. The gray lines extending above and below each data point are error bars that show the uncertainty of each measurement, or the reasonable range of actual possible values. For a single observation, the error on these measurements is remarkably small.The blue line is a best-fit model that takes into account the data, the known properties of WASP-96 b and its star (e.g., size, mass, temperature), and assumed characteristics of the atmosphere. Researchers can vary the parameters in the model – changing unknown characteristics like cloud height in the atmosphere and abundances of various gases – to get a better fit and further
The release of this week’s clutch of images marks the conclusion of the telescope’s commissioning, a lengthy process intended to make sure it is fit for purpose. It is. Management will now be transferred to the Space Telescope Science Institute in Baltimore, which will have the thankless task of allocating time on it to eager astronomers. The good news is that the new estimates of its working life mean many more requests will eventually be fulfilled. The bad is that there may be a long wait. ■
Curious about the world? To enjoy our mind-expanding science coverage, sign up to Simply Science, our weekly newsletter.
Back to Science & technology