The first photos of an extra-solar world were taken by the James Webb Space Telescope (JWST), and we're sure to see much more in the future, as the telescope works ten times better than expected.
Only 20 exoplanets have been directly photographed by astronomers, all from telescopes located on Earth. However, since a significant part of the infrared spectrum is blocked by our planet's atmosphere, it has been difficult to describe the properties of these planets in detail.
According to Sasha Hinkley of the University of Exeter in the United Kingdom, "being here on Earth actually provides a ground of sensitivity to what we can detect, and the lowest-mass planet we've been able to identify to date is roughly two Jupiter masses."
HIP 400 b, the so-called super-Jupiter exoplanet with about seven Jupiter masses and orbiting a star 65426 light-years from Earth, has now been directly imaged by Hinkley and colleagues using JWST. Scientists have succeeded in capturing precisely at a wide range of infrared wavelengths that they previously thought were unreachable.
As a result of these results, says Hinkley, “JWST will violate this sentiment base.” According to him, future observations will reach far below the mass of Jupiter.
It will make it possible for humans to reach planets resembling ice giants in our own solar system. If we're lucky, they could even be Neptune or Saturn-like objects.
HIP 65426 b is easier to visualize, given the planet's age and temperature. The researchers used it to test the JWST's exoplanet imaging capabilities because it had previously been seen by ground-based telescopes. They discovered that the JWST was significantly more sensitive than any previous telescope, and performed 10 times better than predicted.
According to team member Beth Biller of the University of Edinburgh in the United Kingdom, "We have excellent sensitivity with JWST, so we can detect things that are incredibly faint, especially if they are a little further away from the star."
The fact that brightness can vary in these exoplanets “really suggests something like clouds, meaning weather, so that probably means JWST will be sensitive enough to hunt for things like clouds,” Hinkley adds.
Researchers have used various infrared wavelengths to photograph the planet, from the near infrared used in previous photographs to the mid-infrared, which has never been done before. We have more information as we observe these planets over a very wide spectrum of wavelengths, Hinkley said. “We now know more about the chemistry of their atmospheres and the chemical enrichment of these atmospheres. This is very important because learning about the materials and chemical components of these planets can help us understand how they formed.
Because HIP 65426 b orbits very closely to its parent star, imaging can be difficult due to the stark disparity in brightness. To view the image at various wavelengths, Hinkley and his team used a coronagraph to block the star's light. According to Biller, the processing methods used by JWST's two infrared instruments, the NIRCam and MIRI, result in slightly different views of the planet.
According to Michael Merrifield of the University of Nottingham in the United Kingdom, JWST is not actually the best exoplanet imaging tool due to its high demand for studying various other celestial objects.
But above all it is such an important development that I believe it will likely lead to new regimes for us.
However, there are restrictions. JWST cannot take high-resolution images of planet-like exoplanets in our solar system because they are too far from Earth and are very difficult to study. But Hinkley believes that information from the JWST mission will eventually result in a telescope that can see an Earth-sized planet orbiting another star.
He claims that these discoveries are truly the beginning of learning to coronagraph in space. “Ultimately, we want to one day get this image of an exo-Earth,” he says.