14 June 2023
On a clear night sky, head out to the backyard with star charts or night sky apps and look up. Can you spot the constellation Pisces? Did you know there is a strange world in the direction of this constellation? Astronomers recently found evidence of stranger things happening on this planet!
WASP-76b is an exoplanet almost the size of Jupiter, located 634 light years away from our Earth. The planet orbits super close to its host star – almost 12 times closer than mercury is to the Sun! So close that the star heats its atmospheres to scorching 2000°C.
The planet often links its strange behaviour to extreme temperatures. For one, it causes the planet to swell up, increasing its volume to nearly six times that of Jupiter. Not only this, most of the mineral-and-rock forming elements – which would otherwise be hidden in the atmospheres –, now begin to vaporise and reveal themselves. Just like steam coming from a hot cup of tea!
Using the Gemini North Telescope operated by NSF’s NOIRLab, an international team of astronomers detected 11 rock-forming elements in the atmosphere of WASP-76b. Researchers found sodium, potassium, lithium, nickel, manganese, chromium, magnesium, vanadium, barium, calcium, and iron.
The amount of elements found in the exoplanet match both to that of its host star and our Sun. This confirms that unlike rocky planets, gas-giant Jupiter and Saturn form quite like stars through mixing of gas and dust in the protoplanetary disc. While rocky planets like our Earth form from accretion and clash of dust, rocks and planetesimals.
The strangeness doesn’t end just yet. For the first time astronomers also found the presence of a very strange but significant molecule – vanadium oxide – on an exoplanet. Vanadium oxide is to an exoplanet what ozone is to our Earth.
With such an interesting chemical profile and plenty of important clues from WASP-76b, scientists can now explore how giant gas planets and planetary systems form in our own Solar System and elsewhere in the cosmos.
Image:This artist impression illustrates how astronomers using the Gemini North telescope, one half of the International Gemini Observatory operated by NSF’s NOIRLab, have made multiple detections of rock-forming elements in the atmosphere of a Jupiter-sized exoplanet, WASP-76b Credits: International Gemini Observatory/NOIRLab/NSF/AURA/J. da Silva/Spaceengine/M. Zamani
Did you know that if temperatures were not too high, the elements detected by the researchers would normally form rocks like here on Earth? The gas giants in our Solar System also have similar chemical composition as that of WASP-76b. Because these planets are too cold for the elements to vaporise into the atmosphere, they remain trapped in it forever and are almost never detected in our Solar System.