AsianScientist (Nov. 27, 2018) – An international team of astronomers has discovered a candidate planet in orbit around Barnard’s star, the closest single star to the Sun and second only to the Alpha Centauri triple stellar system. The researchers published their findings in Nature.
At only six light-years from Earth, Barnard’s star appears to move across Earth’s night sky faster than any other star. This red dwarf star is among the least active red dwarfs known and represents an ideal target to search for exoplanets.
Since 1997, several instruments have been used to measure the star’s subtle back-and-forth wobble. An analysis of the data collected up to 2015, including observations from the HIRES spectrometer on the Keck telescope in the US and the European Southern Observatory’s HARPS and UVES spectrometers, suggested the wobble could be caused by a planet with an orbital period of about 230 days.
In the present study, researchers including Dr. Lee Man Hoi from the University of Hong Kong have verified that the wobble was indeed due to a planet orbiting Barnard’s star.
“The tremendously successful Kepler space telescope had shown us that statistically, most stars should have planets around them, so it is gratifying that astronomers have now discovered planets around both of the Sun’s closest neighbors,” said Lee.
The researchers monitored Barnard’s star with high-precision spectrometers and found that the planet candidate, named Barnard’s star b (or GJ 699 b), is a super-Earth with a minimum of 3.2 Earth masses. It orbits its cool red parent star every 233 days near the so-called snow-line of the star, which means GJ 699 b is likely to be a frozen world with temperatures of about -150ºC. Without an atmosphere, it is improbable that the planet can sustain liquid water on its surface.
“For the analysis, 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. The combination of all data led to a total of 771 measurements,” said study leader Dr. Ignasi Ribas of the Institute of Space Studies of Catalonia and the Institute of Space Sciences in Spain.
The article can be found at: Ribas et al. (2018) A Candidate Super-earth Planet Orbiting Near the Snow Line of Barnard’s Star.
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Source: University of Hong Kong; Photo: Shutterstock.
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