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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SIT formed to probe second sexual assault case against expelled Cong MLA Mamkootathil
Thiruvananthapuram (PTI): A Special Investigation Team (SIT) has been constituted to probe a second case of sexual assault against expelled Congress MLA Rahul Mamkootathil, police officials said on Friday.
The SIT will be led by G Poonguzhali, Assistant Inspector General at the Police Headquarters.
The team also includes a DSP rank officer and sub-inspectors, officials added.
The second sexual assault complaint was received by the Kerala Pradesh Congress Committee, which it forwarded to the state police chief.
ALSO READ: Cong expels rape-accused MLA Mamkootathil from party's primary membership
Following this, the Crime Branch registered a case and launched an investigation.
Crime Branch officials said the email complaint contained only the sender's email ID and no other contact details.
As part of the probe, they have sent a reply email requesting that the complainant contact them and provide her statement.
The complainant has alleged that she was sexually assaulted under the false promise of marriage, a Crime Branch official said.
However, details such as the location and date of the alleged incident are not currently available to the police.
The SIT will attempt to trace the sender of the email and record her statement, which is crucial for further investigation, the officer said.
Mamkootathil was expelled from the Congress party on Thursday after a court here rejected his anticipatory bail petition in another rape case.
Police said he is currently absconding, and a manhunt is underway in Kerala and neighbouring states.
