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Exoplanets – planets outside of our solar system – continue to provide astronomers with fascinating glimpses of other worlds, including the one designated WASP-76b. On this hell-like planet, almost the size of Jupiter, daytime surface temperatures are warm enough to vaporize iron, which could fall as rain on the slightly cooler night side.
Now, researchers have taken another look at WASP-76b and have concluded that it may in fact be hotter than previously thought. Key to this conclusion is the discovery of ionized calcium, which would need “considerably warmer” conditions to form than those previously described in the studies.
As we know from previous research, temperatures on the WASP-76b’s surface are expected to climb to around 4,400 degrees Fahrenheit (2,246 Celsius) on the day’s side – but that could be an underestimate if the new Updated temperature profile turns out to be more accurate.
“We see so much calcium; it’s a really strong characteristic,” says astrophysicist Emily Deibert of the University of Toronto in Canada. “This spectral signature of the ionized calcium could indicate that the exoplanet has very strong winds in the upper atmosphere, or that the atmospheric temperature on the exoplanet is much higher than we thought.”
Discovered in 2016, WASP-76b is known as a “hot Jupiter” exoplanet because it is so close to its star – an orbit takes only 1.8 Earth days. It is about 640 light years from our position in the Universe. It is also locked by the tides, which means that the same side of the planet always faces its star, which itself is slightly hotter than our Sun.
Here, the researchers used data from the Gemini North Telescope in Hawaii to examine the zone of moderate temperature on the planet, the border between day and night. They used a transit spectroscopy process, where light from a star from an exoplanet shines through its atmosphere, to Earth.
The quality and composition of this light allow us to make calculations on the atmosphere at different depths. In this case, the team was able to identify a rare trio of spectral lines, readings that indicate the presence of ionized calcium.
“It is remarkable that with today’s telescopes and instruments, we can already learn a lot about atmospheres – their constituents, their physical properties, the presence of clouds and even large-scale wind models. – planets orbiting stars hundreds of light years away, “says astronomer Ray Jayawardhana of Cornell University in New York.
Spectroscopy techniques such as the one used here allow astronomers to uncover all kinds of secrets about exoplanets located hundreds of light years away (or more): everything from details of the planet’s rotation to wind patterns to the surface.
This means that as more and more of these exoplanets are discovered and cataloged, researchers can group them together for easier reference. Ultimately, we end up learning more about our place in the Universe and where we might find other life forms.
This study is part of a multi-year project involving a minimum of 30 exoplanets, called Exoplanets with Gemini Spectroscopy (ExoGemS). Once the project is completed, experts should have a much better idea of the diversity of atmospheres that exist on these distant and exotic worlds.
“As we remotely sense dozens of exoplanets, spanning a range of masses and temperatures, we will develop a more complete picture of the true diversity of alien worlds – from those warm enough to harbor iron rains to others. with more moderate climates, from those heavier than Jupiter to others not much bigger than Earth, ”explains Jayawardhana.
The research was published in the Letters from astrophysical journals.
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