Using the NASA/ESA/CSA James Webb Space Telescope, astronomers have captured a direct image of HIP 65426b, an extrasolar gas giant about 6 to 12 times more massive than Jupiter.
This Webb/MIRI image shows the super-Jupiter exoplanet HIP 65426b. Image credit: NASA / ESA / CSA / Webb / A. Carter, University of California, Santa Cruz / ERS 1386 team / A. Pagan, STScI / DSS.
HIP 65426b is located approximately 363 light-years away in the constellation of Centaurus.
First discovered in 2017, the planet is 1.5 times larger than Jupiter and up to 12 times as massive.
It orbits the A2-type star HIP 65426 (also known as HD 116434), which is almost 3,000 K hotter and twice as massive as the Sun.
HIP 65426b orbits the parent star at a distance of 92 AU (astronomical units); it is sufficiently distant from the star that Webb can easily separate the planet from the star in the image.
“This is a transformative moment, not only for Webb but also for astronomy generally,” said Dr. Sasha Hinkley, an astronomer at the University of Exeter.
“I think what’s most exciting is that we’ve only just begun,” said Dr. Aarynn Carter, an astronomer at the University of California, Santa Cruz.
“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.”
These Webb images show HIP 65426b in different bands of infrared light: 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. These images look different 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 HIP 65426, which has been subtracted using the coronagraphs and image processing. The bar shapes in the NIRCam images are artifacts of the telescope’s optics, not objects in the scene. Image credit: NASA / ESA / CSA / Webb / A. Carter, University of California, Santa Cruz / ERS 1386 team / A. Pagan, STScI / DSS.
The Near-Infrared Camera (NIRCam) and Mid-Infrared Instrument (MIRI) aboard Webb are both equipped with coronagraphs, which are sets of tiny masks that block out starlight, enabling the space telescope to take direct images of certain exoplanets like this one.
“It was really impressive how well the Webb coronagraphs worked to suppress the light of the host star,” Dr. Hinkley said.
Taking direct images of exoplanets is challenging because stars are so much brighter than planets.
HIP 65426b 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 alien world 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.
“One of the things we’re most excited about is that we now have the ability to measure the brightness of planets at wavelengths longer than 5 microns,” said Dr. Jordan Stone, an astrophysicist at the U.S. Naval Research Laboratory.
“So we now have this, highly precise, machine that’s giving us the ability to, to measure light from planet surfaces across a really broad wavelength range. And so this is really going to transform our understanding of giant planets.”
“Obtaining this image felt like digging for space treasure,” Dr. Carter said.
“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.”
A paper on the findings will be published in one of the AAS journals.
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Aarynn L. Carter et al. 2022. The JWST Early Release Science Program for Direct Observations of Exoplanetary Systems I: High Contrast Imaging of the Exoplanet HIP 65426b from 2-16 μm. AAS journals; arXiv: 2208.14990
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