NASA’s James Webb Space Telescope (JWST) has captured its first direct image of a planet outside the solar system, known as an exoplanet. The exoplanet does not have a rocky surface, and is not habitable, because it is a gas giant.
Webb, the world’s most powerful space telescope, imaged the exoplanet HIP 65426b using four different light filters. The image shows how Webb’s powerful infrared gaze can capture worlds beyond our solar system.
Webb’s infrared vision foreshadows the way the telescope’s future observations will reveal more information than ever about exoplanets, according to NASA.
Webb Has Captured The Exoplanet In Four Different Bands Of Light
The exoplanet’s purple-coloured image shows the Near Infrared Camera (NIRCam) instrument’s view at three micrometres, the blue image represents NIRCam’s view at 4.44 micrometres, the yellow image shows the Mid-Infrared Instrument’s (MIRI’s) view at 11.4 micrometres, and the red image represents MIRI’s view of the exoplanet at 15.5 micrometres.
The four colours represent views of the exoplanet in different bands of infrared light. Within each instrument, a set of masks, called a coronagraph, is present.
How Did Webb Block Starlight?
The coronagraph blocks out the host star’s light so that the exoplanet can be seen. The host star of the exoplanet is known as HIP 65426.
In each of the four images, a small white region can be seen. This region represents the host star of the exoplanet.
In Webb’s final image, the small white region has been subtracted using the coronagraphs and image processing.
In the NIRCam images, bar-shaped regions can be seen. These are artefacts of Webb’s optics, and not objects in the scene.
An international team of astronomers led by Sasha Hinkley, associate professor of physics and astronomy at the University of Exeter in the United Kingdom, made these observations.
More About Exoplanet HIP 65426 b
Exoplanet HIP 65426 b is about six to 12 times the mass of Jupiter. Webb’s observations could help astronomers narrow down the mass of the exoplanet even further. The exoplanet is twice as massive as the Sun, and roughly three times farther away from its star than Neptune is to the Sun.
The exoplanet is about 15 to 20 million years old, and is considered young, compared to Earth, which is 4.5 billion years old. HIP 65426 b is located 350 light-years away from Earth in the constellation Centaurus.
In 2017, astronomers discovered the exoplanet using the SPHERE instrument on the European Southern Observatory’s Very Large Telescope in Chile. Astronomers captured images of the exoplanet using short infrared wavelengths of light.
Since Webb observes celestial objects at longer infrared wavelengths, the telescope can reveal new details. Ground-based telescopes are not able to detect these intricate details in celestial bodies because of the intrinsic infrared glow of Earth’s atmosphere
According to NASA, Webb’s first capture of an exoplanet hints at future possibilities for studying distant worlds.
Exoplanet HIP 65426 b is about 100 times farther from its host star than Earth is from the Sun. This means that the exoplanet is sufficiently distant from its host star for Webb to easily separate the planet from the star in the image.
Both NIRCam and MIRI are equipped with coronagraphs. Since these sets of tiny masks blocked out starlight, Webb was able to capture a direct image of the exoplanet.
NASA’s Nancy Grace Roman Space Telescope will demonstrate an even more advanced coronagraph. It is slated to launch later this decade.
Since stars are much brighter than planets, it is challenging to capture direct images of exoplanets. The exoplanet imaged by Webb is more than 10,000 times fainter compared to its host star, in the near-infrared spectrum, and a few thousand times fainter in the mid-infrared spectrum.
Due to the particulars of Webb’s optical system, and how the telescope translates light through the different optics, the exoplanet appears as a slightly different shaped blob of light in each filter image.
However, this is not the first direct image of an exoplanet taken from space. NASA’s Hubble Space Telescope has captured direct images of exoplanets in the past.
A “Transformative Moment” For Astronomy: Researcher
In a statement released by NASA, Hinkley said this is a “transformative moment”, not only for Webb, but also for astronomy generally.
He also said that it was “really impressive” how well the Webb coronagraphs worked to suppress the light of the host star.
Aarynn Carter, a postdoctoral researcher at the University of California, Santa Cruz, who led the analysis of the images, said obtaining this image felt like “digging for space treasure”. He also said that at first, all he could see was light from the star, but with careful image processing, he was able to remove that light and uncover the planet.
Carter hinted at the possibility of Webb discovering previously unknown planets. Webb can also directly image Uranus and Neptune.
Webb is an international collaboration between NASA, European Space Agency (ESA) and the Canadian Space Agency (CSA). After decades of wait, Webb was launched into space on December 25, 2021, atop an Ariane 5 rocket from the Guiana Space Centre located near Kourou, French Guiana.
Webb will examine every phase of cosmic history, from the first luminous glows after the Big Bang to the formation of galaxies, stars, and planets, and the evolution of our own solar system.