Astronomers find exoplanet with cloud-free atmosphere
London, May 8: Astronomers have found that a planet outside our solar system, which is similar to Saturn in mass and exceeds the size of Jupiter by 20 per cent, has an atmosphere free of clouds.
The hot gas giant, WASP-96b, periodically transits a Sun-like star 980 light years away in the southern constellation Phoenix.
Using the the European Southern Observatory's Very Large Telescope in Chile, the team studied the atmosphere of WASP-96b when the planet passed in front of its host-star.
This enabled the team to measure the decrease of starlight caused by the planet and its atmosphere, and thereby determine the planet's atmospheric composition.
"We've been looking at more than twenty exoplanet transit spectra. WASP-96b is the only exoplanet that appears to be entirely cloud-free and shows such a clear sodium signature, making the planet a benchmark for characterisation," said lead author of the study Nikolay Nikolov from University of Exeter in Britain.
Just like an individual's fingerprints are unique, atoms and molecules have a unique spectral characteristic that can be used to detect their presence in celestial objects.
The spectrum of WASP-96b shows the complete fingerprint of sodium, which can only be observed for an atmosphere free of clouds, according to the study published in the journal Nature.
It has long been predicted that sodium exists in the atmospheres of hot gas-giant exoplanets, and in a cloud-free atmosphere it would produce spectra that are similar in shape to the profile of a camping tent.
"Until now, sodium was revealed either as a very narrow peak or found to be completely missing. This is because the characteristic 'tent-shaped' profile can only be produced deep in the atmosphere of the planet and for most planet clouds appear to get in the way," Nikolov added.
Clouds and hazes are known to exist in some of the hottest and coldest solar system planets and exoplanets.
The presence or absence of clouds and their ability to block light plays an important role in the overall energy budget of planetary atmospheres.
"It is difficult to predict which of these hot atmospheres will have thick clouds. By seeing the full range of possible atmospheres, from very cloudy to nearly cloud-free like WASP-96b, we'll gain a better understanding of what these clouds are made of," explains study co-author Jonathan Fortney, Professor at University of California, Santa Cruz (UCSC), US.
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US VP JD Vance says Lebanon not part of ceasefire, calls it ‘misunderstanding’
Budapest/Washington: US Vice President J D Vance has said that Lebanon was never included in the ceasefire understanding with Iran, describing the confusion as a “legitimate misunderstanding”.
Speaking to reporters before departing from Hungary, Vance said, “I think the Iranians thought that the ceasefire included Lebanon and it just didn’t. We never made that promise.”
He stressed that the United States had not included Lebanon in the scope of the ceasefire at any stage.
His remarks come amid continued Israeli strikes in Lebanon, where more than 200 people were reported killed, even as ceasefire talks between Iran and the US move forward.
Vance said Israel had “offered … to check themselves a little bit in Lebanon because they want to make sure that our negotiation is successful”.
He warned that if Iran allows the situation in Lebanon to affect the negotiations, it could derail the talks.
“If Iran wants to let this negotiation fall apart in a conflict where they were getting hammered over Lebanon, which has nothing to do with them and which the United States never once said was part of the ceasefire, that’s ultimately their choice,” he said.
