Webb Telescope Makes Major Breakthrough With Its First Direct Image Of A Planet Outside Our Solar System
Explanatory astronomers have obtained the first-ever direct images of an exoplanet with JWST.
In a breakthrough for astronomers the James Webb Space Telescope (JWST) has taken its first direct image of a planet outside our solar system.
Called HIP 65426 b, the Jupiter-like planet orbits a dwarf star about 385 light-years from Earth. Its imaging could help scientists find many smaller types of exoplanets.
One of the hardest ways possible to find an exoplanet, the success of JWST’s first attempt at directly imaging comes just days after JWST detected carbon dioxide around another exoplanet.
“The images look even better than the simulated images we produced many years ago,” said Sasha Hinkley, Associate Professor in the Department of Physics & Astronomy at the University of Exeter and Principal Investigator for one of the 13 JWST Early Release Science Programs.
“This is a particularly exciting beginning to this new era capturing photons directly from exoplanet atmospheres at totally new wavelengths that should last for the next 20 years or so,” said Hinkley, describing the moment as a “major milestone.”
The images were published online as a pre-print as part of the JWST Early Release Science Program for Direct Observations of Exoplanetary Systems.
This image shows the exoplanet HIP 65426 b in different bands of infrared light, as seen from the … [+]
What is HIP 65426 b?
HIP 65426 b is six to 12 times the mass of Jupiter. According to NASA it takes 630.7 Earth-years to orbit its star from 92 AU—that’s twice as far as Pluto does from our Sun.
It was first discovered in July 2017 by scientists using the Spectro-Polarimetric High-contrast Exoplanet REsearch instrument (SPHERE), a “planet-finder” at the European Southern Observatory’s Very Large Telescope (VLT) in Chile. The discoverers suggested it has a “warm, dusty atmosphere.”
How Webb took this exoplanet image
Astronomers used two of JWST’s key instruments to capture the exoplanet— its Near-Infrared Camera (NIRCam) and its Mid-Infrared Instrument (MIRI).
The glare from a star on the dust around it can make it impossible to detect the faint reflected light from exoplanets around it. Cue a coronagraph, a black disc that is positioned precisely in front of a star to block out its light.
“We picked this star as we knew it had a well-established planet that would be ripe for direct imaging and would therefore be an outstanding first target to test the JWST coronagraphs,” said Hinkley.
NIRCam’s task is to detect light from the earliest stars and galaxies. It’s equipped not only with various filters to create observations at different wavelengths, but also with a coronagraph for blocking the light from a star. That’s exactly what the researchers used to find HIP 65426 b around its host star. The MIRI instrument is a camera and a spectrograph that sees light in the mid-infrared region of the electromagnetic spectrum.
Astronomers used two of JWST’s key instruments to capture the exoplanet— its Near-Infrared Camera … [+]
Webb exceeds expectations
JWST appears to be about 10 times more precise than predicted, according to the authors for whom precision was everything in directly imaging HIP 65426 b. The planet could only be located by first observing the exact structure and intensity of residual starlight around the coronagraph and then subtracting it away to leave behind the planet.
“This structure evolves over time, but because JWST is so stable it doesn’t vary quite as much as our nominal predictions,” said Aarynn Carter, lead author and Postdoctoral Scholar at the University of California, Santa Cruz. “The telescope is more sensitive than we expected, but it is also very stable,” he said, adding that it was a credit to all the people behind the design, construction and commissioning of JWST.
Why this direct image of an exoplanet is so important
The images of HIP 65426 b are evidence that, yes, JWST can transform astronomers’ ability to directly image planets and tease-out details about their atmospheres and composition.
Its chief weapon is its ability to see in various wavelengths of infrared light referred to as microns—that no telescope has previously been able to. “This is the first time we’ve ever imaged a planet beyond five microns and now that we have this capability we can cover the full luminous wavelength ranges of these objects,” said Carter. That new wavelength will help scientists calculate exoplanets’ luminosity, mass, temperature and radius.
It could also help scientists find smaller exoplanets. “We’ve shown that JWST is sensitive to lower masses of exoplanets than we’ve been able to detect before,” said Carter. “Previously we’ve been limited to detections of super-Jupiters, but now we have the potential to image objects similar to Uranus and Neptune for the right targets.”
Illustration of the exoplanet (extrasolar planet) Wasp 39b. Wasp 39b is a so-called hot Saturn, with … [+]
JWST vs. ground-based telescopes
It appears the JWST can directly detect exoplanets with an order of magnitude improvement over ground-based telescopes. As well as being able to see in the infrared, JWST’s measurements are much more precise.
“Ground-based observing in the infrared is very difficult because of the higher thermal background and telluric contamination from Earth’s atmosphere,” said Carter.
The observation of HIP 65426 b is the first in proposal 1386, a 39-hour program to push JWST’s high contrast imaging to the limit and establish reference-quality data.
The proposal will also study two other targets—a dusty disk around a star called HD 141569A (320 light-years distant in the constellation of Libra) and an exoplanet orbiting a binary star, called VHS 1256b (41 light-years distant in the constellation of Corvus).
JWST’s carbon dioxide detection
Just a few weeks ago it was revealed that JWST had detected carbon dioxide in the atmosphere of an exoplanet for the first time. It discovered the gas—an important component of Earth’s atmosphere—was discovered on July 10, 2022 in the atmosphere of WASP-39b, the first exoplanet JWST made an official observation of. WASP-39b is a hot gas-giant orbiting a Sun-like star about 700 light-years from Earth.
Webb is the most ambitious and complex space science telescope ever constructed, with a massive 6.5-meter primary mirror that will be able to detect the faint light of far-away stars and galaxies. It’s designed solely to detect infrared light emitted by distant stars, planets and clouds of gas and dust.
Wishing you clear skies and wide eyes.
