SCIENTISTS have discovered a super-Earth three-times the mass of our own planet orbiting the closest single star to the sun.
The international team, led by Ignasi Ribas of the Institute of Space Studies of Catalonia (IEEC), studied more than 18 years of data, combined with new observations from a range of facilities to confirm their findings.
They said the super-cold exoplanet, illustrated in an artist’s impression, above, took 233 days to orbit Barnard’s star, which is the closest star to the Sun and second only to the Alpha Centauri triple stellar system. Barnard’s star b, as it has been named, orbits its parent near the snowline, at a distance where water would be perpetually frozen. With no atmosphere, its temperature is likely to be around minus 150C, making it unlikely that it could sustain water in liquid form.
The astronomers’ interest was triggered by the fact that Barnard’s star – which is only six light years from Earth – appeared to move across the sky faster than any other star, but moves with a slight “wobble”.
Data analysis suggested this could be caused by a planet with an orbital period of around 230 days, but more measurements were needed to confirm this.
“We used observations from seven different instruments, spanning 20 years, making this one of the largest and most extensive datasets ever used for precise radial velocity studies,” said Ribas.
“The combination of all data led to a total of 771 measurements.
“After a very careful analysis, we are over 99% confident that the planet is there, since this is the model that best fits our observations. However, we must remain cautious and collect more data to nail the case in the future, because natural variations of the stellar brightness resulting from star spots can produce similar effects to the ones detected.”
The team’s findings are published in the journal Nature.
Cristina Rodríguez-López, from the Instituto de Astrofísica de Andalucía and co-author of the paper, added: “This discovery means a boost to continue on searching for exoplanets around our closest stellar neighbours, in the hope that eventually we will come upon one that has the right conditions to host life.”
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