Barnard's Star is a small, ancient kind of sun called a red dwarf. But the methods we've used to detect majority are biased toward finding large planets that orbit close to their host stars.
Yet much about the planet around Barnard's Star remains uncertain.
"This technique has been used to find hundreds of planets", said Butler, one of the pioneers of the radial velocity method. Planets around red dwarfs tend to skew to Earth-size - bigger planets around these kinds of stars are more rare - and red dwarfs are by far the most common kind of star in the galaxy, outnumbering more massive stars like the Sun by more than five to one. Their search was also responsible for unveiling Proxima b, which orbits the nearest star beyond the sun, red dwarf Proxima Centauri. This is where planets are detected using gravity-both the star's influence on the planet and the planet's influence on the star.
"We knew we would have to be patient". Though it is extremely close, Barnard's star is too faint to be seen with the naked eye'.
Researchers looked at two decades worth of data from seven different telescopes to pick up the planet, according to Forbes. Alpha Centauri's triple-star system (including Alpha Centauri A and B, plus Proxima Centauri) are the only stars nearer. While the planet orbits the star, its gravitational pull causes the star to wobble. The newly discovered super-Earth is the second closest known exoplanet to our planet and orbits the fastest moving star in the Earth's night sky. "The stars are known to show activity cycles, so this might be a cycle of stellar activity [rather than a planet]". This makes it a super-Earth-a planet that has a mass somewhere between Earth and Uranus or Neptune. This imparts a Doppler shift on its light, shifting it to longer wavelengths (redshifting) when it moves away and toward shorter wavelengths (blueshifting) when it moves toward us. It's just six light-years from our sun, and possibly twice as old. They watched for small counter movements in the star that indicate a massive body (a planet) is in orbit.
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The researchers used the radial velocity method for their detection.
The planet is about the same orbital distance from its star as Mercury is from our sun, making a full pass around the star every 233 days.
"In the end, we believe firmly enough the object is there", Ignasi Ribas of the Institut de Ciències de l'Espai and lead author of the paper says.
Given how close the exoplanet is to our solar systems, future missions and telescopes should be able to provide more insight into the composition of the surface, and the atmosphere of the planet. "Hopefully we got it right this time", said Dr. Guillem Anglada-Escudé, an astronomer in the School of Physics and Astronomy at Queen Mary University of London. "Only when we had done that did the signal become very clear and obvious".
In the 1930s, Dutch-American astronomer Peter van de Kamp began a quest to study Barnard's star that lasted for most of his 93 years.
"Difficult detections such as this one warrant confirmation by independent methods and research groups", he said in an essay accompanying the new study. "This is the result of a large collaboration organized in the context of the Red Dots project, which is why it has contributions from teams all over the world including semi-professional astronomers coordinated by the American Association of Variable Star Observers".
However, the new data contain tentative hints of a second planet orbiting Barnard's Star even further out than the Super-Earth.