The possible presence of a ring of light in the atmosphere of a distant exoplanet has been detected for the first time

Researchers have shown the possible presence of a beautiful, halo-like, colorful ring of light in the atmosphere of an exoplanet. The ring of light is an atmospheric formation consisting of colorful, concentric circles of light, which can only be created when special conditions are met at the same time.

The CHEOPS (Characterizing ExOplanet Satellite) space telescope of the European Space Agency (ESA) and other telescopes were able to detect this extraordinary, rarely seen ring in the atmosphere of WASP-67b, a hellishly hot gas giant orbiting 637 light-years away from Earth. from the analysis of your data.

Although this phenomenon can also be observed in the Earth’s atmosphere, it has only been detected once on other planets, namely in the atmosphere of Venus. The fact that a ring of light has now been discovered on a planet outside the solar system is an extraordinary result: by knowing the properties of the atmospheric halo, researchers can draw conclusions about the hitherto unknown properties of a mysterious, distant world.

According to data from the CHEOPS space telescope, the halo planet WASP-76b has a closed orbit, so it is always dark and night on one side, and day on the other side. A ring of light, like a rainbow, can be created when the light is reflected from the – as yet unknown composition – clouds.

According to Olivier Demangeon, the head of the research, it is no coincidence that we have not seen such a phenomenon on the surface of another planet until now: “Special conditions must be met for the creation of the ring of light. First of all, it is important that the atmosphere is stable and that its particles are completely uniform and nearly spherical. Second, the central star must illuminate the planet at exactly the right angle so that the observer – in our case the CHEOPS space telescope – looks at it from the right direction.”

If its presence is proven, this beautiful ring of light can serve as a perfect tool for a more detailed examination of the planet and the star that illuminates it.

“What we keep in mind is the size scale that we can talk about in this case.” – explained Matthew Standing, a participant in the research. – “WASP-76b is a giant planet located several hundred light-years away, and its surface is so hot that liquid iron is most likely falling from its clouds as precipitation. In these hellish, chaotic conditions, we managed to detect the possible presence of a halo-like light ring. Although the signal is very weak and faint, it is unmistakably reflected in the measurement data.”

This result also illustrates how the CHEOPS space telescope is capable of observing extraordinary, never-before-seen phenomena.

The special light curve of the infernal planet

WASP-76b is an ultra-hot Jupiter-type gas giant. Although its mass is 10% less than that of the largest planet in our solar system, it is almost twice its size. It orbits its host star in a closed orbit, namely 12 times closer than Mercury to the Sun, as a result of which the exoplanet inflated due to the strong radiation from its star.

WASP-76b has been the subject of intense research since its discovery in 2013, and to this day it has developed an extraordinarily hellish image. One side of the planet always faces the central star, so the temperature there can reach 2400 °C. Under these conditions, the elements that form rocks on Earth melt and vaporize on WASP-76b’s surface, then precipitate on the slightly “cooler” night side, creating iron clouds from which iron rain falls.

In addition, it seemed mysterious about the planet that, passing in front of its central star, the researchers thought they discovered strange, asymmetrical, “limb-like” shapes in its atmosphere. Several telescopes, such as NASA’s TESS (Transiting Exoplanet Survey Satellite), Hubble and Spitzer space telescopes, have examined the planet before, but the shape of the halo-like ring of light came to light from the joint examination of CHEOPS and TESS data. CHEOPS intensively sampled the passage of the planet WASP-76b in front of its star: it made 23 measurements of the transit in 3 years. By analyzing this data, it was possible to show that the planet’s eastern terminator line (the line on the planet’s surface that separates day and night) turns out to be surprisingly bright. This allowed the researchers to determine the origin of the signal.

“This is the first time we have observed such a sharp change in the light curve of an exoplanet’s coverage.” Olivier said. – “Based on this, we conclude that the extraordinary light phenomenon is caused by a strong, localized, direction-dependent reflection phenomenon, a light ring.”

What can the presence of the ring of light indicate?

Although the ring of light takes on a pattern similar to a rainbow, the two phenomena are not exactly the same. A rainbow is formed when light passes through media of different densities, such as air and water, which leads to refraction. Then the different wavelength components of the light bend in different directions, and in this way the white light breaks down into the colors of the rainbow.

On the other hand, a ring of light is created when the light passes through a narrow gap, for example between the droplets of a cloud or fog. The path of light is then also bent, and as a result an interference pattern consisting of colored concentric circles is created, in which dark and light regions alternate.

If we could prove the presence of the light ring, we could conclude that the clouds of the exoplanet’s atmosphere consist of almost perfectly spherical droplets that have persisted or regenerated for at least 3 years. In order for such clouds to form, the temperature of the atmosphere must be nearly constant over a long period of time. By detecting the ring of light, it was possible to highlight that special conditions prevail on the planet WASP-76b.

What is perhaps even more important, the detection of the halo also shows how important these amazing, but very difficult to detect, atmospheric phenomena can be. Thus, for example, we can even detect light reflected from rivers or lakes, which is an essential condition for the habitability of the planet.

However, further measurements, such as with the James Webb Space Telescope or ESA’s upcoming Ariel telescope, are needed to clearly prove the existence of the light ring.

The results described here were published in the journal Astronomy & Astrophysics.

The original article can be read here.

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