Webb directly images its 1st exoplanet
For the first time, astronomers have used NASA’s James Webb Space Telescope to take a direct image of a planet outside our solar system. The exoplanet is a gas giant, meaning it has no rocky surface and could not be habitable.
The image, as seen through four different light filters, shows how Webb’s infrared gaze can capture worlds beyond our solar system.
Sasha Hinkley, associate professor of physics and astronomy at the University of Exeter in the United Kingdom, led these observations with a large international collaboration. Hinkley said:
This is a transformative moment, not only for Webb but also for astronomy generally.
Webb images exoplanet HIP 65426 b
The exoplanet in Webb’s image, called HIP 65426 b, is about six to 12 times the mass of Jupiter. These observations could help narrow that down even further. It is young as planets go – about 15 to 20 million years old – compared to our 4.5-billion-year-old Earth.
Astronomers discovered the planet in 2017 using the SPHERE instrument on the European Southern Observatory’s Very Large Telescope in Chile. They took images of it using short infrared wavelengths of light. Webb’s view, 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.
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.
NIRCam and MIRI
Since HIP 65426 b is about 100 times farther from its host star than Earth is from the sun, it is sufficiently distant from the star so Webb can easily separate the planet from the star in the image.
Webb’s Near-Infrared Camera (NIRCam) and Mid-Infrared Instrument (MIRI) are both equipped with coronagraphs. Coronagraphs are sets of tiny masks that block out starlight, which enable Webb to take direct images of exoplanets like this one. NASA’s Nancy Grace Roman Space Telescope, slated to launch later this decade, will demonstrate an even more advanced coronagraph.
It was really impressive how well the Webb coronagraphs worked to suppress the light of the host star.
Taking direct images of exoplanets is challenging because stars are so much brighter than planets. The HIP 65426 b planet is more than 10,000 times fainter than its host star in the near-infrared. And it’s 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.
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. At first all I could see was light from the star, but with careful image processing I was able to remove that light and uncover the planet.
Future exoplanet discoveries with Webb?
This is not the first direct image of an exoplanet taken from space. The Hubble Space Telescope has captured direct exoplanet images previously. But HIP 65426 b points the way forward for Webb’s exoplanet exploration.
I think what’s most exciting is that we’ve only just begun. There are many more images of exoplanets to come that will shape our overall understanding of their physics, chemistry and formation. We may even discover previously unknown planets, too.
Bottom line: The James Webb Space Telescope has taken its first image of an exoplanet, or a world outside our solar system. The planet’s name is HIP 65426b.