• Researchers were able to confirm the actual size of Proxima b
  • Proxima b orbits the star closest to the Sun
  • The planet orbits within Proxima Centauri's habitable zone

A team of researchers discovered a planet almost as big as Earth orbiting the closest star to the Sun. According to the researchers, the planet is orbiting within the host star’s habitable zone.

The researchers made the discovery after the size of the planet was confirmed by ESPRESSO, which is the most accurate spectrograph currently in operation. They presented their findings in a study published in Astronomy and Astrophysics.

For the study, the researchers gazed at a star known as Proxima Centauri, which is located about 4.2 light-years from the Sun. During their observations, they used the ESPRESSO spectrograph that is currently installed on the Very Large Telescope in Chile.

The focus of the study is the planet known as Proxima b, which was first detected four years ago by an old spectrograph known as HARPS. Although the researchers were already aware of the planet’s existence, they had no accurate information regarding its size.

Through radial velocity measurements taken by ESPRESSO, which has an accuracy of 30 centimeters per second, the researchers were able to measure Proxima Centauri and its orbiting planet. They learned that Proxima b is about 1.17 times as massive as Earth.

“We were already very happy with the performance of HARPS, which has been responsible for discovering hundreds of exoplanets over the last 17 years,” Francesco Pepe, the co-author of the study, said in a statement. “We're really pleased that ESPRESSO can produce even better measurements, and it's gratifying and just reward for the teamwork lasting nearly 10 years.”

According to the researchers’ observations, Proxima b orbits its host star in 11.2 days. They noted that the planet lies within the star’s habitable zone, that region that has the right conditions to support life.

The researchers stated that Proxima b is about 20 times closer to its star than the distance between Earth and the Sun. From this location, the planet might have liquid water that could harbor living organisms.

Although the planet can be considered a likely candidate for a life-hunting study, the researchers noted that there are other factors that need to be determined first regarding Proxima b’s capability to support life. One of these is the presence of an atmosphere.

“Is there an atmosphere that protects the planet from these deadly rays?” the study’s co-author, Christophe Lovis, stated. “And if this atmosphere exists, does it contain the chemical elements that promote the development of life (oxygen, for example)?”

The planet Proxima b orbiting the red dwarf star Proxima Centauri, the closest star to our solar system, is seen in an undated artist's impression released by the European Southern Observatory, Aug. 24, 2016. Reuters