The James Webb Space Telescope continues, still at the start of its scientific mission, producing extraordinary results. Last week, two new articles brought the first direct images of exoplanets taken by the satellite.
It is important to remember that, although they are rare, we already had, thanks to other observatories, a handful of photographs of exoplanets. The main challenge in recording them directly is the disparity in brightness between them and their parent stars, combined with their proximity to each other. In this way, images of exoplanets are usually restricted to younger ones (which still retain a lot of heat from formation, which makes them brighter in the infrared) and, at the same time, more distant from the central stars.
The new observations follow this pattern, but what they bring back is an unprecedented quality. The first work, published in the arXiv repository and submitted to a journal of the American Astronomical Society, reports the images taken of the exoplanet HIP 65426 b, the first officially photographed by Webb.
Thanks to a coronagraph capable of blocking the light from the central star, the telescope was able to capture an image of that world in all seven filters used. It is a gas giant exoplanet with a mass seven times that of Jupiter, orbiting at about 90 AU (1 astronomical unit is the Earth-Sun distance, 150 million km). The age is estimated at 14 million years (compare the Solar System’s 4.5 billion).
Astronomers have found that the actual performance of Webb is up to ten times higher than predicted, which is exciting for future observations and makes room for more planets to be recorded directly.
The second article concerns the exoplanet VHS 1256 b, which has less than 20 times the mass of Jupiter and orbits at about 150 AU from a brown dwarf (the name given to “aborted stars”, which formed as stars, but did not gain enough mass to maintain the nuclear fusion process in their core). VHS 1256 b itself may be another brown dwarf, given the uncertainty of its mass (brown dwarfs are often separated from gas giant planets in the range of 13 times the mass of Jupiter).
The fact is that Webb obtained the highest fidelity spectrum (the “signature of light”) ever captured from such an object. It was possible to detect the presence of water, methane, monoxide and carbon dioxide, as well as sodium and potassium, in the astro composition. In addition, there is a signal indicating silicate clouds in the atmosphere (it is so hot that rocks are vaporized there), the first time such a detection has been made in a potentially planetary-mass companion.
And these are just the first two results of direct observation of exoplanets. Much more will follow, adding to the photo album – not to mention understanding – of these strange and fascinating worlds.
This column is published on Mondays, in Folha Corrida.
Follow the Sidereal Messenger on Facebook, twitterInstagram and YouTube
