In the past three decades, we have witnessed a great revolution – the dawn of the Exoplanet Era.
Have you ever wanted to see an alien world? A planet orbiting a distant star, light-years away from the Sun? The James Webb Space Telescope (JWST) has just returned its first images of such a world – a planet orbiting a far-off star, as reported by Space.com.
The new images revealed by JWST will be an excellent tool for astronomers to enhance their knowledge of exoplanets (planets outside our Solar System).
Observing Hidden, Distant Worlds
In the past three decades, we have experienced a great revolution – the dawn of the Exoplanet Era. A time when we once believed no other planets orbited distant stars, questioning whether our Solar System was unique. Thanks to advancements in science and technology, we now know that planets are everywhere.
However, the majority of these exoplanets have been discovered indirectly. They orbit their host stars so closely that, with current technology, we cannot observe them directly. Instead, we watch their host stars do something unexpected and infer the presence of these ‘invisible’ exoplanets.
Among all those strange worlds, only a few have been directly observed. For example, the HR 8799 system, which has four giant planets that have been photographed so frequently that astronomers have produced a movie showing them orbiting their host star.
A series of 4 images captured by the James Webb Space Telescope showing the exoplanet world, HIP 65426b, first imaged by the infrared telescope. Source: NASA / ESA / CSA, A Carter (UCSC), ERS 1386 team and A. Pagan (STScI))
To capture JWST’s first direct images of an exoplanet, astronomers pointed the telescope at HIP 65426. The massive companion planet HIP 65426b of this star was discovered through direct imaging in 2017.
The exoplanet HIP 65426b is unusual in several ways – all of which make it a particularly “easy” target for direct imaging. First, it orbits its host star at a significant distance, about 92 times farther than the distance between Earth and the Sun, meaning HIP 65426b is roughly 14 billion kilometers from its star. This creates a “reasonable” distance that facilitates easier observations.
Next, HIP 65426b is a giant world – believed to be several times the mass of Jupiter, the largest planet in our Solar System – hence it is also referred to as a Super-Jupiter. Additionally, it has been previously discovered to be extremely hot, with temperatures at its cloud tops reaching at least 1,200 degrees Celsius.
How Were the Images Captured and What Do They Show Us?
Under normal circumstances, light from HIP 65426 would completely overshadow light from the planet HIP 65426b, despite the distance between them.
To counter this issue, JWST is equipped with a “coronagraph”, a tool that allows the telescope to block light from a bright star to search for fainter objects nearby. This is similar to using your hand to block headlights from a car to see other objects.
Using this coronagraph method, JWST took a series of images of HIP 65426b, each captured at a different infrared light wavelength. In each image, the planet can be clearly seen – a single bright pixel from its hidden position behind its host star.
The first images of JWST of the exoplanet world, HIP 65426b, are displayed at the bottom of a wider image showing its host star. The images were captured at different wavelengths of infrared light. Image source: NASA / ESA / CSA, A Carter (UCSC), ERS 1386 team and A. Pagan (STScI).
NASA indicates that the purple color shows the view from the NIRCam device at 3.00 microns, blue shows the view from the NIRCam device at 4.44 microns, yellow shows the view from the MIRI device at 11.4 microns, and red shows the view from the MIRI device at 15.5 microns. These images look different due to the ways various James Webb instruments capture light.
The small white star in each image marks the position of the host star HIP 65426, which has been dimmed using the coronagraph and image processing.
The researchers leading these observations discovered that JWST is performing about 10 times better than expected – a result that excites astronomers worldwide as they eagerly await what happens next.
Using their observations, they determined that the mass of HIP 65426b is nearly 7 times that of Jupiter. Additionally, the data shows that this planet is hotter than previously thought (with cloud tops exceeding 1,000 degrees Celsius) and has a radius approximately 1.5 times that of Jupiter.
These images paint a picture of a world that is entirely alien, different from anything in our Solar System.
Signs for the Future
Observations of HIP 65426b are just the first signs of what JWST can achieve in imaging exoplanets around other stars.
The astonishing accuracy of the image data suggests that JWST will be able to directly observe smaller planets than previously expected. Instead of being limited to planets larger than Jupiter, it may be able to see planets similar to or even smaller than Saturn.
This is a truly exciting discovery. The fact that JWST can see smaller and fainter planets than anticipated will significantly increase the number of potential exoplanet targets for astronomers.
Furthermore, the precision with which JWST conducts these measurements indicates that we will be able to learn much more about their atmospheres than expected. Repeated observations with the telescope may even reveal details about how these atmospheres change over time.
In the coming years, the international astronomy community looks forward to seeing more images of exoplanet worlds captured by JWST. Although these images may not resemble those in science fiction, they will still revolutionize our understanding of planets around other stars.
According to NASA, the James Webb Space Telescope (JWST) – a collaboration between NASA, the European Space Agency (ESA), and the Canadian Space Agency (CSA) – is currently located about 1.5 million kilometers from Earth, at a position known as the second Lagrange point (L2). The perfect environment and physical conditions at L2 will allow JWST to showcase its infrared observational capabilities.
The Verge reports that the total investment in the JWST space telescope is $10 billion. This nearly $10 billion price tag for JWST accounts for NASA’s lifetime cost, including much of its development process since the early 2000s and the first five years of operation, according to Planetary Society.
