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Astronomers Have Found a Cloud Free Planet Outside Our Solar System

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.

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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.
Astronomers during IAU meet, wikimedia commons

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.

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.
Planets and solar system, Pixabay

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.

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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. (IANS)

Next Story

Astronomers Discover a Disc Very Close to Starving Black Hole

The presence of the black hole disc in such a low-luminosity active galaxy has astronomers surprised

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Astronomers, Disc, Black Hole
The unexpected thin disc of material was found encircling a supermassive black hole at the heart of the spiral galaxy NGC 3147. Pixabay

Using NASA’s Hubble Space Telescope, astronomers have discovered a disc very close to a starving black hole – something that should not be there – based on current astronomical theories.

The unexpected thin disc of material was found encircling a supermassive black hole at the heart of the spiral galaxy NGC 3147, located 130 million light-years away, according to a study published in the journal Monthly Notices of the Royal Astronomical Society.

The presence of the black hole disc in such a low-luminosity active galaxy has astronomers surprised.

Black holes in certain types of galaxies such as NGC 3147 are considered to be starving as there is insufficient gravitationally captured material to feed them regularly.

Astronomers, Disc, Black Hole
Using NASA’s Hubble Space Telescope, astronomers have discovered a disc very close to a starving black hole. Pixabay

It is therefore puzzling that there is a thin disc encircling a starving black hole that mimics the much larger discs found in extremely active galaxies, the study said.

The disc’s material was measured by Hubble to be whirling around the black hole at more than 10 per cent of the speed of light.

At such extreme velocities, the gas appears to brighten as it travels toward Earth on one side, and dims as it speeds away from our planet on the other. This effect is known as relativistic beaming.

Hubble’s observations also show that the gas is embedded so deep in a gravitational well that light is struggling to escape, and therefore appears stretched to redder wavelengths. The black hole’s mass is around 250 million times that of the Sun.

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“This is an intriguing peek at a disc very close to a black hole, so close that the velocities and the intensity of the gravitational pull are affecting how we see the photons of light,” explained the study’s first author Stefano Bianchi of Roma Tre University in Italy.

Of particular interest, this disc of material circling the black hole offers researchers a unique opportunity to test Albert Einstein’s theories of relativity.

“We’ve never seen the effects of both general and special relativity in visible light with this much clarity,” said Marco Chiaberge of the European Space Agency, and the Space Telescope Science Institute and Johns Hopkins University, both in Baltimore, Maryland. (IANS)