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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Jai Bhim: Slogan that energised Dalits was first given at this central Maharashtra village
Chhatrapati Sambhajinagar (PTI): 'Jai Bhim': These two words have come to symbolise the awakening and empowerment of the Dalit community in independent India, but not many people know how it originated.
The slogan, which also encapsulates the immense reverence in which Dr Bhimrao Ramji Ambedkar is held, was first raised at the Makranpur Parishad, a conference organised at Makranpur village in Kannad teshil of today's Chhatrapati Sambhajinagar district in Maharashtra.
Ambedkar, the chief architect of India's Constitution, died on December 6, 1956.
Bhausaheb More, the first president of the Scheduled Castes Federation of Marathwada, organised the first Makranpur Parishad on December 30, 1938.
Dr Ambedkar spoke at the conference and asked the people not to support the princely state of Hyderabad under which much of central Maharashtra then fell, said Assistant Commissioner of Police Pravin More, Bhausaheb's son.
"When Bhausaheb stood up to speak, he said every community has its own deity and they greet each other using the name of that deity. Dr Ambedkar showed us the path of progress, and he is like God to us. So henceforth, we should say 'Jai Bhim' while meeting each other. The people responded enthusiastically. A resolution accepting 'Jai Bhim' as the community's slogan was also passed," More told PTI.
"My father came in contact with Dr Babasaheb Ambedkar in his early years. Bhausaheb was aware of the atrocities the Nizam state committed on Dalits. He told Ambedkar about these atrocities, including the pressure to convert. Dr Ambedkar was strongly against these atrocities, and he decided to attend the 1938 conference," he said.
As Ambedkar was against the princely states, he was banned from giving speeches in the Hyderabad state but was allowed to travel through its territories. The Shivna river formed the border between Hyderabad and British India. Makranpur was chosen as the venue for the first conference because it was on the banks of Shivna but lay in the British territory, ACP More said.
The stage made of bricks, from where Dr Ambedkar addressed the conference, still stands. The conference is organised on December 30 every year to carry forward Ambedkar's thought, and the tradition was not discontinued even in 1972 when Maharashtra experienced one of the worst droughts in it history.
"My grandmother pledged her jewellery for the conference expenses. People from Khandesh, Vidarbha and Marathwada attended it. Despite a ban imposed by the Nizam's police, Ambedkar's followers crossed the river to attend the event," said ACP More.
"This is the 87th year of Makranpur Parishad. We have deliberately retained the venue as it helps spread Ambedkar's thought in rural areas," he added.
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