Back in 2016, the world was left starstruck after scientists stumbled upon a super-earth orbiting the Proxima Centauri, the star closest to the sun, only 4.2 light-years away from our Earth. Now, they have managed to trace a second signal coming from what they believe to be a second super-Earth orbiting around the same low-mass red dwarf star, which means that there could be a neighbouring planetary system with possible signs of life in our very own galaxy.
In a study published in the journal Science Advances, researchers say that the potential second planet in that system, Proxima c, has a mass larger than that of Earth but smaller than Uranus and Neptune, and takes 5.2 Earth years to complete an orbit of Proxima Centauri. It’s six times larger than the previously found super-Earth Proxima b, though the latter is 30 times closer to the star, making its surface warmer and more inhabitable since the Proxima Centauri star is much cooler than our sun. However, due to its proximity to this star, Proxima b is also subjected to intense ultraviolet rays that are ten times stronger than the ones on earth. So, despite having a habitable surface, the radiation level means that elements like hydrogen, oxygen and nitrogen may not exist on it.
The newly discovered planet makes for an interesting subject since further study could help us understand how low-mass planets form around low-mass stars. What’s even more interesting about this particular planet is that it has formed beyond the “snowline” of the system, a metaphorical line after which temperature declines rapidly, leading scientists to believe that any water formed on that surface would be frozen.
After discovering the first planet around Proxima Centauri, scientists wondered whether another planet could exist in that system. So, astronomers traced light signals that appeared to be coming from that direction using the Atacama Large Millimeter/submillimeter Array of telescopes in Chile and examined more than 17 years of radial velocity data to see if the signals were coming from another potential planet. The radial velocity method takes into account gravity and the Doppler effect, in which light increases or reduces in frequency as the targeted source and observed objects around it move toward or away from each other since stars can’t stay still when they have a planet orbiting around them. Instead, they move in small circles responding to the pull of gravity from the planets, effectively changing the light wavelength of the star. Tracing such shifts can help astronomers find planets.
While researchers have warned that the signals they’ve detected could be because of an activity of the star’s magnetic field, the fact that the signal was traced over a period of 1,900 days strongly indicates that it is coming from a planet.
"Even the closest planetary system to us may retain interesting surprises," Fabio Del Sordo,study author and postdoctoral researcher in the department of physics at the University of Crete told CNN. "Proxima Centauri hosts a planetary system that is much more complex than we knew, and we do not know how many unknown features are waiting to be discovered."
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This article originally appeared on VICE IN.