In addition to amazing discoveries, JWST works with other telescopes to produce spectacular images like this M74 “phantom galaxy.”Credit: ESA/Webb, NASA & CSA, J. Lee and PHANGS-JWST team
On the morning of December 25, 2021, the ground in French Guiana literally shook as the Ariane 5 rocket ignited. That roar signaled the beginning of a month-long journey to the current home of the James Webb Space Telescope (JWST) for some 930,000 people. Miles (1.5 million km) from Earth. It took another five months for scientists and engineers to get him to use the 6.5-meter telescope, but it was worth the wait. In his two years since its launch, JWST has changed our view of the universe.
Here’s one person’s take on the observatory’s top 10 discoveries of all time. I don’t want to list my favorites, so I’ve organized the list by distance, from far away to close to space.
Big and bright galaxy at the dawn of the universe
Before JWST, astronomers believed that galaxies began as small clouds of gas, dust, and stars that gradually grew into the island universes we see today. But because the telescope can observe infrared light, it can peer even further into the universe, going back to when galaxies first formed. JWST has discovered some of these young stars dating back less than 500 million years since the Big Bang, and they are much brighter than anyone expected. Galaxies may produce stars more efficiently than predicted, producing large numbers of massive stars at higher rates. Or, most interestingly, it could be more massive than astronomers thought possible. Scientists also discovered more advanced structures in some spiral galaxies during “cosmic noon,” when the universe was two to three billion years old and stars were most actively formed. did.
Early supermassive black holes
We all know that black holes grow by swallowing passing stars and clouds of gas and dust. So it’s surprising to find supermassive black holes (SMBHs) lurking in the early Universe, when they didn’t have much time to feed on their surroundings. JWST has discovered multiple black holes with a mass of about 1 billion solar masses dating back 800 million years after the Big Bang. Perhaps even more importantly, the telescope discovered much smaller SMBHs even earlier, with masses ranging from a million to tens of millions of solar masses. This could give astronomers enough data to understand how these giant creatures evolve.
dust of youth in the universe
Dust appears everywhere around us. They appear in fluffy bunnies hiding under your bed, in dark clouds that obscure your view of the Milky Way, and as spectral traces of distant galaxies. Most dust contains carbon, which is a relative latecomer to the universe because early stars had to synthesize the element from an initial supply of hydrogen and helium. However, JWST discovered dust in the galaxy just a billion years after the Big Bang. This dust has a unique chemical fingerprint, suggesting it may be a mixture of graphite- or diamond-like particles made in early stars. It opens new doors to dust production and galaxy formation.
Tighten the tension in the universe
In astronomy, few numbers are more important than the Hubble constant (the rate of expansion of the universe). The European Space Agency’s Planck spacecraft combined observations of the cosmic background radiation with the Standard Model of Cosmology to determine its value at 67 km per second per megaparsec. Observations of Cepheid variable stars and type Ia supernovae by the Hubble Space Telescope and other instruments show higher values (about 73 km/s/Mpc), giving rise to the so-called Hubble tension. JWST confirmed this higher value with greater accuracy. The discrepancy between the two methods suggests that scientists are either missing something in the way the universe works or making multiple errors in measurements that all work in the same direction.
Studying star formation in detail
Stars form in dense clouds of gas and dust. Unfortunately, the dust blocks visible light, making much of the process invisible. However, the infrared rays observed by JWST penetrate dust, opening a new window into the birth of stars. For example, it revealed thousands of new stars buried deep in the Eagle Nebula (M16), which Hubble couldn’t reach. JWST also showed surprising details of part of the nearby constellation of Rhô Ophiuchus. The telescope’s images reveal dozens of young, low-mass stars and the jets they emit, illuminating the surrounding clouds of hydrogen molecules.
dusty supernova remnant
Exactly 340 years ago, the light from an exploding star reached Earth for the first time. Today, we observe the supernova remnant, known as Cassiopeia A (Cas A), as a 10 light-year wide shell of debris. Cas A’s stunning infrared beauty comes from wispy tendrils of gas and the soft glow of warm dust. Dust is of interest to astronomers because it is a fundamental building block of planets and life. They believe that most cosmic dust is formed from heavy elements ejected by supernovae, but previous studies have been unable to explain the amount of this material seen in early galaxies. Scientists hope that JWST’s observations of Cas A and other supernova remnants will help them learn more about their origins.
Deep within the center of the Orion Nebula (M42) are at least 40 planet-sized objects with binary companion stars. This object, called JuMBO (short for Jupiter-Mass Binary Objects), defies all expectations. Many stars have companion stars, but astronomers had not expected planetary-mass objects to have companions. According to star formation theory, it is impossible to create such a small object, and if it were to develop in a circumstellar disk like a planet, it would not be able to withstand forced ejection. Astronomers will likely need to revise their ideas about star and planet formation or come up with new theories to create these JuMBOs.
Molecular exoplanet revolution
Although images get the most attention, spectroscopy plays a major role in the JWST exploration. This allows astronomers to determine the redshift, or distance, of distant galaxies and to analyze the chemical composition of celestial objects. Nowhere is this more important than in the study of exoplanet atmospheres. JWST’s infrared capabilities allow it to detect molecules that are invisible to light. Among its many discoveries, JWST discovered: Methane, carbon dioxide, and dimethyl sulfide in K2-18 bthe star has a rocky world in its habitable zone, suggesting there may be an ocean of water on its surface.
ring around ring nebula
The Ring Nebula (M57) in the constellation Lyra ranks as one of the most beautiful planetary nebulae in the sky, the final state of a Sun-like star. JWST revealed intricate details of the ring itself, which is made up of about 20,000 clumps of molecular hydrogen. But what really makes M57 stand out in the JWST images is a series of 10 concentric arcs that extend beyond the outer edge of the main ring. Astronomers believe the arc first formed near the dying star when the ejected gas interacted with a low-mass companion star orbiting at a distance on the order of the distance between the sun and Pluto. There is.
Diving into a protoplanetary disk
Planets form in dusty, gaseous disks surrounding young stars. JWST’s observations not only provided unprecedented details about these protoplanetary disks, but also provided tantalizing clues to the precursors of life. Around the nearby star Fomalhaut, the telescope found three nested bands of warm dust, suggesting the planet formed a disk shape. The observatory also detected water vapor in the inner disk surrounding PDS 70, indicating that terrestrial planets forming there have access to water. JWST then discovered methyl cations, molecules that are likely to play an important role in interstellar organic chemistry and the origin of life, in the protoplanetary disk surrounding young stars d203-506 in the Orion Nebula.