The James Webb Space Telescope photographs its first exoplanet

The host star and, below, the exoplanet seen by James Webb using four different light filters. / NASA/ESA/CSA

Science | Astrophysics

HIP 65426 b is a gas giant, a super-Jupiter that is about 385 light-years from Earth.

james webb space telescope has photographed its first exoplanet, its first world around a star that is not the Sun. It is a gas giant that is between six and eight times the mass of Jupiter and between 15 and 20 million years old. A youngster compared to Earth, which is about 4.5 billion years old. HIP 65426 b is about 385 light years away, was discovered in 2017 and is a hundred times further from its star than we are from the Sun. This great distance is what has allowed the NASA and ESA observatory to separate in its image from that of his star.

The Universe, according to James Webb

It is not the first photo of an exoplanet taken by a space telescope, since Hubble has taken several, but it demonstrates the potential of the new observatory to hunt new worlds. "This is a transformative moment not only for Webb, but also for astronomy," said Sasha Hinkley, an astronomer at the University of Exeter who led the observations.

Webb has imaged the gas giant, which appears in the center of each image in a different color, using four different light filters. Purple color shows the view of the NIRCam instrument at 3.00 micrometers; blue, that of the NIRCam instrument at 4.44 micrometers; yellow, that of the MIRI instrument at 11.4 micrometers; and red, that of the MIRI instrument at 15.5 micrometers. The small white star inset in all photos marks the location of the host star, HIP 65426, obliterated by coronagraphs and image processing.

This is how the Hubble and James Webb telescopes see the same region of the Cosmos

James Webb's Near-Infrared Camera (NIRCam) and Mid-Infrared Instrument (MIRI) are equipped with coronagraphs, masks that block starlight, allowing the telescope to directly image some exoplanets. Photographing worlds in other solar systems is difficult because they can be hidden in the brightness of their star. In this case, HIP 65426 b's brightness is more than 10,000 times dimmer than its sun in the near infrared and several thousand times dimmer in the mid-infrared.

"It was really impressive how well Webb's coronagraphs worked to suppress the light from the host star," says Hinkley. “Getting this image was like digging for space treasure. At first, all I could see was the light from the star, but with careful image processing I was able to remove that light and discover the planet," says Aarynn Carter of the University of California, who led the analysis of the images. . "I think the most exciting thing is that we have only just begun," added the researcher.

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