Evidence of a Super-Earth Found Orbiting Proxima Centauri

The star closest to our sun may be home to a planet 6 times more massive than Earth.

With a minimum mass of about six times that of Earth, researchers say a possible Super-Earth may exist orbiting the nearest star to the sun—Proxima Centauri, orbiting it at a distance of 1.5 times that between the Earth and the Sun.

The new study adds great value to previous work that points to the existence of a complex planetary system orbiting the sun’s nearest star, Proxima Centauri.

In 2016, astronomers had announced that there was a temperate planet, of similar size to Earth, orbiting Proxima Centauri. Studies in 2017 showed signs of the existence of dust belts around the star, which were perhaps the remnants of the system’s formation.

The planet discovered in 2016—Proxima b—orbits the star in the so-called habitable zone, the right distance from the star for liquid water to exist on its surface.

Experts have further said that since the planet lies within the habitable zone—also called the Goldilocks zone—there is a possibility that life as we know it may have evolved on the surface.

A new study has now offered major insight into the planetary system that exists orbiting Proxima.

The years following the discovery of Proxima b, astronomers analyzed radial velocity data gathered by a number of instruments such as the UVES (Ultraviolet and Visual Echelle Spectrograph), and the HARPS (High Accuracy Radial Velocity Planet Searcher), installed at the European Southern Observatory (ESO) in the Atacama Desert in Chile.

Data revealed that the star, Proxima Centauri, was being pulled by the gravity of a world that was orbiting it: Proxima b.

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The group of researchers led by Guillem Anglada-Escudé of Queen Mary University London didn’t see evidence of any other planet orbiting the star at the time, but that possibility couldn’t be ruled out.

Artist's impression of the exoplanet Proxima Centauri b shown as of a arid (but not completely water-free) rocky Super-Earth. This appearance is one of several possible outcomes of current theories regarding the development of this exoplanet, while the actual look and structure of the planet is known in no ways at this time. Proxima Centauri b is the closest exoplanet to the Sun and also the closest potentially habitable exoplanet as well. Image Credit: Wikimedia Commons.
Artist’s impression of Proxima Centauri b. Image Credit: Wikimedia Commons.

Now, a new paper offers conclusive evidence that Proxima b may not be alone in its journey orbiting Proxima Centauri.

A Super-Earth Proxima c

Published in the journal Science Advances, researchers analyzed old data and new measurements of the star.

After going through a treasure trove of data and measurements spanning nearly 18 years, the experts unearthed evidence of the likely existence of another planet around Proxima Centauri, at least 6 times more massive than Earth; a so-called Super-Earth.

The new Super-Earth candidate planet—Proxima c—is believed to complete one orbit around its host star every 5.2 years.

However, despite orbiting the nearest star to Earth, around which a possibly habitable planet already exists, the researchers say that the likelihood that the newly found planet can support life is low because it takes more than five years to circle its star.

“Given the low luminosity of the host star and the orbital radius of the planet, it receives very low insolation,” co-author of the study, Mario Damasso revealed As explained by space.com, insolation is the solar radiation that reaches a planet’s surface. According to Damasso, the temperature on Proxima c is likely around minus 233 degrees Celsius.

For now, the Super-Earth around Proxima Centauri remains no more than a candidate planet, and in order to confirm its existence, a great deal of work will be needed. This data may be gathered by the European Space Agency’s star-mapping Gaia spacecraft.

“According to our study, if Gaia will deliver the data with the expected quality, and in the absence of any unknown impediment, the detection can be reliably confirmed or dismissed,” Damasso explained.

The experts are also considering to search for Proxima c by means of direct imaging, making use of photographs captured by SPHERE, the Spectro-Polarimetric High-contrast Exoplanet REsearch tool installed on the Very Large Telescope in Chile.

The researchers have said that there is an 83% probability that Proxima c really exists.

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