When you think of the results of NASA’s James Webb Space Telescope (JWST), images of colorful clouds swirling in nebulae, galaxies older than you’ve ever seen, and infant stars being born are probably what come to mind. . In its first year into space, NASA’s new high-performance telescope made the cover of a magazine. Scientific American, Billboards in Times Square, and computer screens of avid astronomers and ordinary readers. Audiences around the world, including the President of the United States, have marveled at the universe seen from this marvelous machine.
But one of JWST’s greatest accomplishments has been largely forgotten, not underestimated. You may have missed it or ignored the image as a monotonous dot. Nothing compares to the grandeur of the Carina Nebula.
The most exciting JWST result to date, I believe, is that point: the first telescopic image of an exoplanet, a planet around another star.
Admittedly, as an astronomer whose research focuses on this exact subject, I may be a little biased. But listen. I literally cried for joy at my computer when I saw the first image.
These tiny globular blobs are light from a real planet known as HIP 65426 b, nearly 10 times the size of Jupiter and nearly 400 light-years from Earth. This star orbits a star much larger than our Sun and is very young. In fact, it’s so young that it’s still warm from the primordial heat of its formation and glows brightly in the infrared. These infrared photons traveled directly from another world, reaching JWST’s magnificent golden honeycomb mirrors and creating the images we see. They are more than just dots.
It is incredible that mankind was able to see another planet directly. The task can be compared to photographing fireflies in the city lights hundreds of miles away. Planets are so faint compared to the bright stars that orbit around them that to observe them, you must hold up their starlight to reveal the planet underneath. Astronomers solve this problem by filtering starlight with an item called a coronagraph, which blocks out the star’s bright central region, and using adaptive optics techniques to keep the image stable and sharp.
The first directly imaged planet was 2M1207b, a gas giant five times larger than Jupiter discovered in 2004 by a telescope high in the Chilean desert. About ten years later, 51 Eridanus b, the smallest planet ever directly imaged, was discovered. This is just twice the size of Jupiter. Direct imaging is currently limited to larger planets of this type.Telescopes like Kepler and TESS find planets by looking for tiny dips in starlight, called transits., They have discovered thousands of exoplanets so far, but only about 50 have been documented by direct imaging.
Given the difficulty, why is direct imaging so attractive? First, the orbits of exoplanets are beautifully displayed in direct images. There is no need to untangle complex secondary signals as in many other detection techniques. Instead, we can just observe the movements of planets, such as the planets in the HR 8799 system, a close-up version of the outer solar system.
More importantly, direct imaging provides a unique window into exoplanet atmospheres through their spectra. Spectra are the most valuable tool for astronomers to explore the universe, as they provide information about the chemical composition, temperature, magnetic field, etc. of a celestial body. A spectrum is just the light from an object spread out over the entire rainbow, usually missing part of the rainbow. those are the clues. When an atom absorbs light, it produces spectral lines characteristic of the element it absorbs, forming a fingerprint that is unique to each chemical. Exoplanet spectra reveal what’s going on in the planet’s atmosphere, including possible signs of life.
Following JWST’s first exoplanet image release last fall, March saw the release of the first direct spectrum of an exoplanet described as “the highest fidelity spectrum of a planetary-mass object yet.” I was. While this exoplanet VHS 1256b is a far from habitable, hot, sandy, wind-swept world, its exquisite spectrum reveals how much more information we now have about distant worlds, well beyond our previous capabilities. Prove that you can get it. JWST has the distinct advantage of being in space above Earth’s nasty atmosphere. The air around our planet blurs images and blocks certain wavelengths of light, such as long-wave infrared. These lights are very useful for directly characterizing exoplanets. The space telescope can also resolve spectral details of planets about 100 times finer than previous direct imagers on Earth.
The first direct spectra of planets and planet-sized objects photographed by JWST for the first time represent a major step forward for direct imaging, both of which are weak spots in exoplanet detection, and demonstrate its potential. Direct imaging will lead to new discoveries as we search for life and move toward characterizing planets holistically, rather than just identifying them.
While other exoplanet search methods (such as transit spectroscopy) can obtain spectra, high-contrast imaging is unique in that it can peer into past clouds and obtain detailed atmospheric data in its original state. It’s nothing. It is extremely important for the search for biosignatures, traces of life. This goal is so important that a major commission of the National Academy of Astronomy and Astrophysics, known as the Decade of Exploration, recently identified the search for a habitable world as humanity’s top priority. the entire astronomical community.
Decadal Survey also has plans for two major telescope projects with high-contrast imaging as a primary feature: the Extremely Large Telescope (ELT) on Earth and the Large Ultraviolet, Optical and Infrared Space Telescope. The ELT is the next generation of major telescopes on Earth with a giant mirror more than 30 meters in diameter, including the 30-meter Telescope, the Giant He Magellan Telescope and the European Very Large Telescope. These facilities would greatly improve today’s largest optical telescopes, such as the Keck Observatory in Hawaii, which is about 10 meters in diameter.
To build a mirror this big, engineers have to combine separate mirror segments into a honeycomb shape, like JWST’s famous golden mirror. Such complex devices present more engineering challenges than solid mirrors, requiring scientists to align every segment with painstaking precision. We have been practicing this technology on the ground for many years, but JWST is the first large-scale test of segmented mirrors in space, and it is performing admirably, a step in the right direction for future large-scale observatories. is.
NASA is also already planning to build its next major space observatory, the Habitable World Observatory (HWO), hopefully in the 2040s. Both ELT and HWO aim to take the first images of an Earth-like exoplanet and will build on current direct imaging techniques developed for observatories like JWST. Observations currently being made at the JWST also find important avenues for exoplanet science, and astronomers need to learn as much as they can about exoplanets now to choose the best targets for his HWO. Because there is
Direct imaging is the future of exoplanet exploration and could very well be the way to discover the first signs of extraterrestrial life. The first planet directly imaged by JWST is a monumental step in the thrilling road ahead of us. They may seem like insignificant dots, but they promise to make our wildest sci-fi dreams come true.
This is an opinion and analysis article and the views expressed by the author are not necessarily those of the author. Scientific American.
