Astronomers Discover 'One In A Million' Super-Earth With an Earth-Like Orbit

Astronomers from the University of Canterbury (UC) has discovered a spectacular new exoplanet at the heart of the Milky Way Galaxy. The planet is important as it is one of just a handful of similar exoplanets identified so far.

According to the researchers, the super-Earth is comparable to Earth in both size and orbit. A paper published in the Astronomical Journal describes the exoplanet finding and the planet's features. 

Astronomers Dr. Antonio Herrera Martin and Associate Professor Michael Albrow, both of UC's School of Physical and Chemical Sciences in the College of Science, worked with international researchers to detect the super-Earth.

The planet is said to be a rare world in the cosmos. According to the researchers, the super-Earth is in orbit around a dim dwarf, maybe a brown dwarf, or a failed star. The extraterrestrial world takes around 617 Earth days to circle its star, yet its orbit would fall somewhere between Earth and the planet Venus in our own solar system.

Astronomers utilized the solar system as a reference point, according to UC. The host star has a mass of around 10% that of our Sun. The planet's mass is estimated to be somewhere between that of Earth and that of Neptune, and its orbit is estimated to be somewhere between Earth and Venus. It's one of a handful exoplanets discovered by scientists that has a similar size and orbit to Earth.

The scientists did not discover the super-Earth by directly watching it, nor did they discover it using the transit technique or by studying how it interacts with its star. Rather, scientists found the super-Earth by observing how its host star distorts and magnifies light like a lens, a process known as gravitational microlensing.

Dr. Herrera Martin explained: “The combined gravity of the planet and its host star caused the light from a more distant background star to be magnified in a particular way. We used telescopes distributed around the world to measure the light-bending effect,”

It is incredibly unusual to discover a planet by microlensing. According to astronomers, microlensing effects influence around one in a million stars in the Milky Way at any given time. What makes this revelation even more unusual is that such an observation does not occur frequently.

“The probabilities of catching a planet at the same time are extremely low,” UC astronomers have explained.

The microlensing event that led to the finding of the exoplanet is formally known as OGLE-2018-BLG-0677.