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.
Let the Truth be known. If you read VB and like VB, please be a VB Supporter and Help us deliver the Truth to one and all.
French President Macron concludes Mumbai visit
Mumbai (PTI): French President Emmanuel Macron, along with First Lady Brigitte Macron, left Mumbai for New Delhi on Wednesday after concluding his engagements here, including bilateral talks with Prime Minister Narendra Modi.
They were seen off at Chhatrapati Shivaji Maharaj International Airport by Maharashtra Governor Acharya Devvrat, Chief Minister Devendra Fadnavis and Deputy CM Eknath Shinde.
On Tuesday, Macron held discussions with Modi as part of efforts to further strengthen India-France strategic ties.
During the Mumbai visit, the French president and his wife also met some of India's top filmmakers and actors, and had an animated exchange with them about cinema, culture and collaboration.
President Macron is on an official visit to India from February 17 to 19 at the invitation of PM Modi to participate in the AI Impact Summit hosted by India in the national capital Delhi, besides the bilateral summit in Mumbai.
PM Modi will inaugurate the summit on February 19. As many as 20 heads of states, including French President Macron, will be present at the inaugural session, Electronics and IT Secretary S Krishnan said.
