‘Exoplanet twice size of Earth discovered’

TORONTO: An international team of scientists has discovered a new exoplanet twice the size of Earth, about 145 light-years away from our planet, by using data from NASA'S Kepler Space Telescope.

Wolf 503b is located in the Virgo constellation and orbits its star every six days and is thus very close to it, about 10 times closer than Mercury is to the Sun, researchers said.

"Wolf 503b is one of the only planets with a radius near the gap that has a star that is bright enough to be amenable to more detailed study that will better constrain its true nature," said Bjorn Benneke, a professor at Universite de Montreal in Canada. "It provides a key opportunity to better understand the origin of this radius gap as well as the nature of the intriguing populations of 'super-earths' and 'sub-neptunes' as a whole," said Benneke.

In May, when the latest release of Kepler K2 data came in, the researchers ran a programme that allowed them to find as many interesting candidate exoplanets as possible. Wolf 503b was one of them.

The programme the team used identifies distinct, periodic dips that appear in the light curve of a star when a planet passes in front of it.

In order to better characterise the system Wolf 503b is part of, the astronomers first obtained a spectrum of the host star at the NASA Infrared Telescope Facility. This confirmed the star is an old 'orange dwarf ', slightly less luminous than the Sun but about twice as old, and allowed a precise determination of the radius of both the star and its companion.

Wolf 503b is interesting, firstly, because of its size, researchers said. Thanks to the Kepler telescope, the researchers know that most of the planets in the Milky Way that orbit close to their stars are about as big as Wolf 503b, somewhere between that the size of the Earth and Neptune (which is 4 times bigger than Earth).

The reason for interest in the Wolf 503b system is that the star is relatively close to Earth, and thus very bright, researchers said. Because of its brightness, Wolf 503 will also be a prime target for the upcoming James Webb Space Telescope, they said.

Using a technique called transit spectroscopy, it will be possible to study the chemical content of the planet's atmosphere, and to detect the presence of molecules like hydrogen and water. This is crucial to verify if it is similar to that of the Earth, Neptune or completely different from the atmospheres of planets in our solar system.

"By investigating the nature of Wolf 503b, we will understand more about the structure of planets near the radius gap and more generally about the diversity of exoplanets present in our galaxy," said Merrin Peterson from Universite de Montreal.