Astronomers Find Rare “Super-Earth” Towards the Centre of Our Galaxy

The planet was discovered using the gravitational microlensing technique

A “Super-Earth” has been found closer to the centre of our galaxy through a rare observation by astronomers. The newly discovered planet, though heavier than our Earth, is one of those few planetary bodies that are similar to the Earth in terms of size and orbit. The planet’s parent star has roughly 1/10th the mass of our Sun. The mass of the planet itself is nearly half the mass of Earth and Neptune combined, according to the researchers. The distance of the planet from its star is roughly equal to the distance between our Sun and a point between Venus and Earth.

Researchers at the University of Canterbury (UC) were part of a team that collaborated for the discovery and found the new planet. Lead researchers in the finding, Dr Antonio Herrera Martin and Associate Professor Michael Albrow from the University of Canterbury’s School of Physical and Chemical Sciences in the College of Science, collaborated with an international team for this investigation. The research paper was published in The Astronomical Journal.

The paper’s lead author, Dr Herrera Martin, while mentioning that the discovery was extremely rare, mentioned on the University website, “To have an idea of the rarity of the detection, the time it took to observe the magnification due to the host star was approximately five days, while the planet was detected only during a small five-hour distortion. After confirming this was indeed caused by another ‘body’ different from the star, and not an instrumental error, we proceeded to obtain the characteristics of the star-planet system”

Not many planets like this one have been discovered so far with the size and orbit similar to that of our Earth. This planet completes one revolution around its parent star in about 617 days. The researchers discovered the planet using a technique called gravitational microlensing.

Dr Herrera Martin explained the technique. He told the University website, “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.”

The astronomers mentioned that microlensing effect is rare because only about one in a million stars in the galaxy get affected by the effect at a particular time. They also said that these observations do not repeat and catching a planet at the time of the effect has a very low probability.

For this observation, the researchers used three identical telescopes in Chile, Australia, and South Africa. Most of these events happened due to single stars. However, Dr Herrera Martin noticed that there was an unusual shape to the light output from this event. After months of analysis, they concluded that the event happened due to a star with a low-mass planet.