Astronomers find potentially habitable ‘super-Earth’ exoplanet

Astronomers have discovered three potential “super-Earth” exoplanets orbiting a relatively nearby orange dwarf star, marking an important development in the search for habitable planets.

This groundbreaking discovery was made by an international team of researchers, including Dr Ancy Anna John, a post-doctoral researcher from the School of Physics and Astronomy at the University of St Andrews.

The exoplanets are orbiting Star HD 48948, located approximately 55 light-years from Earth. These planets revolve around their host star in 7, 38, and 151 Earth days, respectively. Notably, the outermost exoplanet candidate resides in the habitable zone of its host star, where conditions could allow liquid water to exist without boiling or freezing. This region, often referred to as the Goldilocks zone, is considered ideal for potentially supporting life.

The international research, led by Dr Shweta Dalal from the University of Exeter was published in the journal MNRAS today ( Monday 24 June), and highlights the importance of the discovery, noting that this orange star is somewhat similar to our Sun and represents the closest planetary system to host a Super-Earth in the habitable zone around a Sun-like star. 

Dr Dalal said: “The discovery of this Super-Earth in the habitable zone around an orange star is an exciting step forward in our quest to find habitable planets around solar-type stars.”

These potential Super-Earths, planets with a mass greater than Earth but significantly less than the Solar System’s ice giants Uranus and Neptune, were identified through the HARPS-N Rocky Planet Search program. Over a decade, the team collected nearly 190 high-precision radial velocity measurements using the HARPS-N spectrograph.

Radial velocity measurements, which track the star’s subtle movements caused by orbiting planets, are crucial in such discoveries. By analysing the spectrum of light from the star, researchers can determine whether it is moving towards us (blueshift) or away from us (redshift). To ensure the accuracy of their findings, the team employed various methodologies and comparative analyses.

The research revealed three planetary candidates with minimum masses ranging from 5 to 11 times that of Earth. The team suggests that the proximity of the star, combined with the outermost planet’s favourable orbit, makes this system a promising target for future high-contrast direct imaging and high-resolution spectroscopic studies.

Dr John from the School of Physics and Astronomy at St Andrews said: “Providing insights to the human race’s long-standing question, “Are we alone?” is always thrilling. The discovery of these three super-Earth companions around a nearby star, is a crucial stride towards the search for cosmic twin, particularly the outer planet that is found in the habitable zone, orbiting the star in every 151 earth days. This planet emerges as a promising target for our future missions that are devoted to finding habitable worlds, such as NASA’s Habitable Worlds Observatory (HWO),  the Habitable Expolanet Observatory and the European Space Agency’s Large Interferometer For Exoplanets (LIFE) Mission.”

Dr Dalal added: “This discovery highlights the importance of long-term monitoring and advanced techniques in uncovering the secrets of distant star systems. We are eager to continue our observations and look for additional planets in the system.”

This discovery opens new doors for understanding planetary systems and the potential for life beyond our solar system.