It’s been almost a year since the most ambitious and expensive space telescope ever built was launched toward the L2 Lagrange point, on Earth’s far side from the sun.
After a nervous deployment that saw him mirrors i parasol it unfolds correctly while browsing 344 potential points of failurethe 10 billion dollars James Webb Space Telescope (Webb or JWST) has been generating fantastic astronomical data since the summer.
Even less than six months after the observations, this data is transformative and scientists have already used it to make several important discoveries and records. JWST was heralded as a revolutionary telescope before its launch; now that it’s up and running, let’s look at some of the many ways it’s already transforming astronomy.
Seeing the past farther than ever
Inset are close-ups of two high-redshift galaxies seen by JWST. One is at a redshift of 10.5, the other at 12.5. Most of the foreground galaxies are part of the Abell 2744 cluster. (Image credit: NASA/ESA/CSA/T. Treu (UCLA))
To see the precious rare photons from the farthest galaxies in the universethe bigger the telescope, the better, and space telescopes don’t get any bigger than JWST, with its 21-foot (6.5-meter) primary mirror.
But that’s only half the job done, because the farther away an object is, the brighter it is redshifted. The farther a galaxy is from us, the faster it is moving away from us due to the expansion of the universe, so its light is stretched more, shifting the light toward redder wavelengths.
The most distant galaxies, which are also the first galaxies we can see, emit light that is shifted to near-infrared wavelengths by the time it arrives. land. It is this redshift that prompted scientists to design JWST to specialize in near- and mid-infrared light.
The combination of the large mirror and infrared vision has allowed JWST to see galaxies that are more distant and earlier than astronomers can, promising to transform our understanding of how these galaxies are formed.
Before the launch of JWST, it was called the most distant known galaxy GN-z11. It has a redshift of 11.1, which corresponds to seeing the galaxy as it was 13.4 billion years ago, just 400 million years after the big bang. This was the absolute limit of what telescopes before JWST could detect.
But very soon after the first JWST data was released, that record was broken. Astronomers took advantage of foreground galaxy clusters like Abell 2744 that act as gravitational lenses: massive objects like galaxy clusters warp space with their gravity, creating a lensing-like effect. ‘magnification that amplifies the light of more distant objects. Astronomers began to find faint, red spots at the bottom of these lenses, and these spots have turned out to be the most distant galaxies ever seen.
First was a galaxy at a redshift of 12.5, called GLASS-z12 (GLASS is the name of a specific survey program, the “Grism Lens-Amplified Survey from Space”). We see this galaxy as it existed 13.45 billion years ago, or 350 million years after the Big Bang, astronomers calculated.
Galaxies with even larger redshifts soon followed. One, called the Maisie Galaxy, is seen as it existed just 280 million years after the Big Bang, at a redshift of 14.3, while another, at a redshift of 16.7, seen just 250 million years after the Big Bang. There have even been claims for a galaxy at a staggering redshift of 20, which if confirmed would have existed only 200 million years after the Big Bang.
JWST is also working to confirm these findings, using a second instrument to split the light by wavelength. Astronomers have it already confirmed a galaxy at a redshift of 13.2, which we see as it was when the universe was only 325 million years old.
Discovering what lit up the universe
An artist’s rendering of the path of the universe from the Big Bang, right, to the present, left; in between, the first stars and black holes created enough light to end the cosmic dark ages. (Image credit: NASA/STScI)
After the Big Bang, but before stars and galaxies had formed, the universe was dark and surrounded by a haze of neutral hydrogen. Eventually, light, especially ultraviolet radiation, ionized this fog. But where did this light originally come from to end the cosmic dark age?
Astronomers believe the light comes from young, star-filled or active galaxies supermassive black holes, which are surrounded by accretion disks of glowingly hot gas and launch powerful jets into space. The question of which came first—the galaxies or their black holes—is one of cosmology’s greatest enigmas, a kind of chicken-or-egg question.
JWST has already found that the first galaxies it is detecting are brighter and more structured than expected, with distinct disks around bulbous cores already full of stars. This feature suggests that fully formed galaxies were on the scene quickly, but whether they already contained supermassive black holes remains to be seen. Fortunately, JWST is designed to answer that question, and when it does, it will provide a big piece of the puzzle that is the puzzle of the early universe.
Measuring atmospheres of exoplanets
Artist’s impression of the gas giant exoplanet WASP-39b; JWST has characterized its atmosphere. (Image credit: NASA/ESA/CSA/J. Olmsted (STScI))
Astronomers have found more than 5,000 exoplanets and counting, but despite this remarkable upswing, we still know next to nothing about many of them. JWST is not designed to discover new exoplanets, but it aims to paint much more detailed pictures of known worlds by doing something called transit spectroscopy.
When a planet passes in front of its star, some of the star’s light filters through the planet’s atmosphere, and molecules in the atmosphere can absorb some of that starlight, creating lines dark in the star’s spectrum, a barcode-like breakdown of light by wavelength. . Knowing what’s in a planet’s atmosphere, or even if it has an atmosphere, can teach astronomers how a planet may have formed and evolved, what its conditions are like, and what chemical processes take place on it. atmosphere
The atmospheric composition of the exoplanet WASP-39b. (Image credit: NASA/ESA/CSA/J. Olmsted (STScI))
The first results have been very encouraging. In August, astronomers announced that JWST had made the first confirmed detection of carbon dioxide in the atmosphere of an exoplanet, in this case WASP-39b, which is 700 light years away. Later in November, astronomers released one more full spectrum showing the absorption lines of elements and molecules in WASP-39b’s atmosphere, including not only carbon dioxide but also carbon monoxide, potassium, sodium, sulfur dioxide, and water vapor.
The findings were described as the most detailed analysis of an exoplanet’s atmosphere to date.
The spectrum showed that there was much more oxygen in the planet’s atmosphere than carbon, as well as an abundance of sulfur. Scientists think the sulfur must have come from numerous collisions that WASP-39b experienced with smaller planetesimals when it was forming, giving us clues about the planet’s evolution that could also indicate how the gas giants in our solar system, jupiter i Saturn, format In addition, the existence of sulfur dioxide is the first example of a product of photochemistry on a planet beyond the solar system, as the compound is formed when ultraviolet light from a star reacts with molecules in an atmosphere planetary
Looking for hints of life and habitability
Artistic representation of the seven planets of the TRAPPIST-1 system. (Image credit: NASA/JPL-Caltech)
Studies of planets like WASP-39b are one thing, but one of the holy grails of exoplanet science is finding another planet that is habitable, like Earth, and JWST is well positioned to characterize alien worlds.
The aforementioned observations of WASP-39b bode well for future studies of the planets TRAPIST-1 system of seven rocky planets orbiting a red dwarf star located 40.7 light years from Earth. Four of these worlds are in the star’s putative habitable zone, where temperatures would allow liquid water to persist on the surface; given the right conditions, they could be habitable to varying degrees.
Initial observations with JWST focus on TRAPPIST-1c, which is the easiest to observe. Models predict it will have a similar atmosphere Venus, with a lot of carbon dioxide. Although TRAPPIST-1c is likely too hot to be habitable, determining whether it has an atmosphere and, if so, whether that atmosphere has carbon dioxide will be a major step toward characterizing Earth-sized worlds . It will also be a big task, requiring 100 hours of observing with JWST, which is approaching 10,000 hours of observing in its first year of science.
Starting with TRAPPIST-1c, things could get more ambitious, with JWST targeting the other worlds in the TRAPPIST-1 system that are most likely to be habitable, as well as similar worlds around other nearby stars. Astronomers will be looking for biosignatures, such as the presence of both methane and oxygen in an atmosphere. The discovery of photochemical reactions in WASP-39b’s atmosphere is also an important step, as photochemical reactions drive the formation of the carbon-based molecular building blocks of life.
Cosmic chemistry and galaxy evolution
Galaxy mergers, like the one in IC 1623 shown here, can drive star formation, which in turn increases a galaxy’s chemical abundance. (Image credit: ESA–Webb/NASA/CSA/L. Armus and A. Evans)
Some stars live for billions and billions of years, but others exist for a short time before exploding into a supernova or expanding to become a red giant which then inflates its outer layers into deep space. In both situations, the stars…