Astrophysicists at the University of Texas at Arlington (UTA) in the US investigated the star system Gliese 832 for additional exoplanets residing between the two currently known alien worlds in this system.
Their computations revealed that an additional Earth-like planet with a dynamically stable configuration may be residing at a distance ranging from 0.25 to 2.0 astronomical unit (AU) from the star.
"According to our calculations, this hypothetical alien world would probably have a mass between 1 to 15 Earth's masses," said Dr Suman Satyal, UTA physics researcher and lead author of the research published in The Astrophysical Journal.
Gliese 832 is a red dwarf and has just under half the mass and radius of the Sun. The star is orbited by a giant Jupiter-like exoplanet designated Gliese 832b and by a super-Earth planet Gliese 832c.
The gas giant with 0.64 Jupiter masses is orbiting the star at a distance of 3.53 AU, while the other planet is potentially a rocky world, around five times more massive than the Earth, residing very close its host star- about 0.16 AU.
"This is an important breakthrough demonstrating the possible existence of a potential new planet orbiting a star close to our own," said Dr Alexander Weiss from UTA.
"The fact that Dr Satyal was able to demonstrate that the planet could maintain a stable orbit in the habitable zone of a red dwarf for more than one billion years is extremely impressive," Dr Weiss said.
The team analysed the simulated data with an injected Earth-mass planet on this nearby planetary system hoping to find a stable orbital configuration for the planet that may be located in a vast space between the two known planets.
Gliese 832b and Gliese 832c were discovered by the radial velocity technique, which detects variations in the velocity of the central star, due to the changing direction of the gravitational pull from an unseen exoplanet as it orbits the star.
By regularly looking at the spectrum of a star- and so, measuring its velocity - one can see if it moves periodically due to the influence of a companion.
"We also used the integrated data from the time evolution of orbital parameters to generate the synthetic radial velocity curves of the known and the Earth-like planets in the system," said Dr Satyal.
"We obtained several radial velocity curves for varying masses and distances indicating a possible new middle planet," he said.