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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New Delhi (PTI): The Delhi High Court was on Tuesday informed that the Manipur government is in favour of having centres outside the troubled north-eastern state for holding civil services preliminary examination, which are scheduled to be held on May 26.
The counsel appearing for the Manipur government told the court, which was hearing a plea seeking setting up of additional examination centres there for civil services and Indian Forest Service aspirants, that the chief secretary has said the government would provide monetary assistance to these aspirants for travel to centres outside the state which is in the grip of a protracted ethnic strife.
In view of the stand taken by the Manipur authorities, a bench headed by Acting Chief Justice Manmohan observed that the examinations may be held outside the state, as held last year, and asked the UPSC counsel to take instructions.
"Take a call. Follow the 2023 pattern then. We will ask UPSC to take instructions. Prima facie we are of this view," the bench, also comprising Justice Manmeet PS Arora, said.
"Counsel for the UPSC is directed to take instructions," the court said.
Petitioner Zomi Students Federation had moved the high court last week, seeking setting up examination centres in Churachandpur and Kangpokpi in the state and reopening of the application window to enable civil services aspirants to opt for a centre of their choice.
The counsel for the Manipur government said the chief secretary of the state, in a letter addressed to him, said the state government is of the opinion that given the situation and to maintain the sanctity of the examination, it may not be appropriate to provide centres in Churachandpur and Kangpokpi.
The letter suggested that students in Manipur, who have to take the civil services examination, may be allotted centres outside the state and financial assistance would be provided to them.
The counsel stated that even last year, the civil services examinations were held in centres outside Manipur.
Counsel for the UPSC had earlier told the court that the commission has already written three letters to the Manipur chief secretary with respect to opening of examination centres in Churachandpur, Kangpokpi and Ukhrul but no response has been received yet.
Manipur plunged into violence in May 2023 over a high court order directing the state government to consider including the non-tribal Meitei community in the list of Scheduled Tribes.
This order led to rampant ethnic clashes. More than 160 people have been killed and several hundred injured since ethnic violence first broke out in the state on May 3 when a 'Tribal Solidarity March' was organised in the hill districts to protest against the majority Meitei community's demand for Scheduled Tribe status.
The matter would be heard next on March 22.