The James Webb Space Telescope’s First Exoplanet Image
While it seems as if Webb was launched not very long ago, in reality, the telescope has been in space for more than 9 months. A few months prior the telescope officially began consistent science operations. Here, scientists have made sure that every second the telescope is working on a long list of goals all sorted, and set on exact dates. Most recently, the agency released information about an exoplanet.
Specifically, just earlier this month, NASA released the James Webb Space Telescope’s first ever image of an exoplanet. The image, taken through four different light filters, highlights how Webb’s powerful infrared gaze can easily capture worlds beyond our solar system. This comes in addition to more information gathered on a host of different exoplanets just last month.
Exoplanets are described as a planet that orbits a star outside the solar system. What makes them so intriguing is the hunt for life and habitable planets within the Universe. Thanks to Webb, we are learning much more about what else is out there. Here I will go more in-depth into the recent exoplanet image, the work Webb has done in this specific field, why it’s important, and more.
New Exoplanet Image
Only a few days prior, NASA released some new images from Webb of a very distant exoplanet. Specfically, on Spetember 1st, the agency tweeted saying, “Talk about out of this world! This is Webb’s first direct image of a planet outside of our solar system, and it hints at Webb’s future possibilities for studying distant worlds.” The image, provided through four different light filters, shows Webb’s ability to easily capture worlds beyond our solar system, pointing the way to future observations that will reveal more information than ever before about exoplanets.
Taking an even closer look at the image, it shows exoplanet HIP 65426 b in different bands of infrared light, as seen from the James Webb Space Telescope. Starting on the left, purple shows the NIRCam instrument’s view at 3.00 micrometers, blue shows the NIRCam instrument’s view at 4.44 micrometers, yellow shows the MIRI instrument’s view at 11.4 micrometers, and red shows the MIRI instrument’s view at 15.5 micrometers. The reason these images look different is because of the ways the different Webb instruments capture light. A set of masks within each instrument, called a coronagraph, blocks out the host star’s light so that the planet can be seen. The small white star in each image marks the location of the host star, which has been subtracted using the coronagraphs and image processing. Its also important to point out that the bar shapes in the NIRCam images are artifacts of the telescope’s optics, not objects in the scene.
To put the size of this exoplanet in perspective, NASA pointed out that the specifc exoplanet in the images is about six to 12 times the mass of Jupiter, and these observations could help narrow that down even further. In addtion, its about as young as planets go, being close to 15 to 20 million years old, compared to our 4.5-billion-year-old Earth. In response to these images, Sasha Hinkley, an associate professor of physics and astronomy said, “This is a transformative moment, not only for Webb but also for astronomy generally.
Back in 2017, astronomers discovered the planet using the SPHERE instrument on the European Southern Observatory’s Very Large Telescope in Chile and took images of it using short infrared wavelengths of light. Webb’s view however, at longer infrared wavelengths, reveals new details that ground-based telescopes would not be able to detect because of the intrinsic infrared glow of Earth’s atmosphere. The agency points out that researchers have been analyzing the data from these observations and are preparing a paper they will submit to journals for peer review. But Webb’s first capture of an exoplanet already hints at future possibilities for studying distant worlds. Since this specific planet is about 100 times farther from its host star than Earth is from the Sun, it is sufficiently distant from the star that Webb can easily separate the planet from the star in the image. As you can imagine, taking direct images of exoplanets is challenging because stars are so much brighter than planets. The exoplanet in these recent images is more than 10,000 times fainter than its host star in the near-infrared, and a few thousand times fainter in the mid-infrared.
In each filter image, the planet appears as a slightly differently shaped blob of light. That is because of the particulars of Webb’s optical system and how it translates light through the different optics. The agency finished by highlighted the fact that while this is not the first image ever taken of an exoplanet, it marks the beginning of Webb’s journey and a hopeful future ahead of it.
Webb & Exoplanets
While the first exoplanet images taken earlier this month are fascinating, it joins a host of additional information the telescope has gathered in the just last few weeks alone. Not long ago in late August, NASA reported that Webb had found carbon dioxide in a distant exoplanet’s atmosphere. Specfically, the JWST recently captured an astonishingly detailed rainbow of near-infrared starlight filtered through the atmosphere of a hot gas giant 700 light-years away. The transmission spectrum of exoplanet WASP-39 b, based on a single set of measurements made using Webb’s Near-Infrared Spectrograph and analyzed by dozens of scientists, represents a hat trick of firsts. it marked Webb’s first official scientific observation of an exoplanet; the first detailed exoplanet spectrum covering this range of near-infrared colors; and the first indisputable evidence for carbon dioxide in the atmosphere of a planet orbiting a distant star. The results are indicative of Webb’s ability to spot key molecules like carbon dioxide in a wide variety of exoplanets – including smaller, cooler, rocky planets – providing insights into the composition, formation, and evolution of planets across the galaxy.
Based on the information gathered, NASA created an illustration that shows what this exoplanet could look like. WASP-39 b is a hot, puffy gas giant with a mass around one fourth of Jupiter and a diameter 1.3 times greater than Jupiter, orbiting just 4,500,000 miles from its star. The star is fractionally smaller and less massive than the Sun. Because it is so close to its star, the exoplanet is very hot and is likely to be tidally locked, with one side facing the star at all times. This observation provides important insights into the composition and formation of the planet. The finding is also indicative of Webb’s unique ability to detect and measure carbon dioxide in the thinner atmospheres of smaller, rocky planets.
Whats so exciting about this observation from Webb, is the fact that no observatory has ever measured such subtle differences in brightness of so many individual colors across the 3 to 5.5-micron range in an exoplanet transmission spectrum before. Access to this part of the spectrum is crucial for measuring abundances of gases like water and methane, as well as carbon dioxide, which are thought to exist in many different types of exoplanets. Understanding the composition of a planet’s atmosphere is important because it tells us something about the origin of the planet and how it evolved. “Carbon dioxide molecules are sensitive tracers of the story of planet formation,” said Mike Line of Arizona State University, another member of this research team. “By measuring this carbon dioxide feature, we can determine how much solid versus how much gaseous material was used to form this gas giant planet. In the coming decade, JWST will make this measurement for a variety of planets, providing insight into the details of how planets form and the uniqueness of our own solar system.”
Transiting planets like this exoplanet, whose orbits can be observed edge-on rather than from above, can provide researchers with ideal opportunities to probe planetary atmospheres. In this case, during a transit, some of the starlight is eclipsed by the planet completely (causing the overall dimming) and some is transmitted through the planet’s atmosphere. Because different gases absorb different combinations of colors, researchers can analyze small differences in brightness of the transmitted light across a spectrum of wavelengths to determine exactly what an atmosphere is made of. With its combination of inflated atmosphere and frequent transits, this specific exoplant is an ideal target for transmission spectroscopy. These capabilities from Webb combined with the observatory’s recent real images of a distant exoplanet highlight what we can expect in the future. Exoplanets are especially exciting to research for a variety of reasons and the James Webb Space Telescope is beginning to provide fascinating results.
Conclusion
Webb has been very busy since it was originally launched over 9 months ago. After completing all of its deployments, alignment, and more, the telescope was finally ready for consistent science operations. Since then it has already provided a host of invaluable information. We will have to wait and see how it progresses and the impact it has on the space industry.