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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State govt will approach SC like Tamil Nadu if Governor rejects bills: Minister Priyank Kharge
Bengaluru: Rural Development and Panchayat Raj Minister Priyank Kharge said on Tuesday that the state government will be forced to fight against the Governor, like the Tamil Nadu government did, if the bills passed by the Karnataka government continued to be rejected by Governor Thaawar Chand Gehlot.
The Governor has returned to the government the Karnataka State Rural Development and Panchayat Raj University Bill, which focuses on replacing the Governor as the head of universities, asking for clarifications from the government.
Addressing reporters in the city on Tuesday, Minister Kharge said the government had faced similar rejection from the Governor earlier too. It had also witnessed similar situations in Tamil Nadu and Kerala, where the Governor had returned bills passed in the legislature. Admitting that the government would provide the necessary clarifications to Gehlot, Kharge said that, if the Governor was still not convinced, the state government would have to approach the Supreme Court ‘like Tamil Nadu did’.
He accused the Governor of violating the legislature’s decisions and causing a feud between the Governor and the government. He also pointed out that a bill was discussed in the legislature and passed through a voting system.
Kharge, who is spokesperson for the Karnataka government, further alleged that the BJP and the RSS were using the Governor’s office as the branch office of the party and state headquarters of the Sangh. He also accused Governor Gehlot of ‘murdering’ democracy by following the orders of the Central government and overruling the decisions of the Karnataka Legislature.
