Compared to our own Sun, the red dwarf being orbited by this super Earth is just 0.4 percent as bright. "We just don't know". A few telescopes with coronagraphs-devices for masking a star's light-have directly imaged a few large planets in wide orbits, but something like Barnard's star b will require the greater resolution of giant telescopes coming in the next decade, such as Europe's 39-meter Extremely Large Telescope. "Fortunately, our long-running Keck planet search program gave us the years we needed to gather enough precision radial velocity data with HIRES to begin to sense the presence of a planet".
A potentially rocky super-Earth orbits one of our closest stellar neighbors, Barnard's star, only 6 light-years away. This method takes advantage of that fact that not only does a star's gravity obviously influence the planet orbiting it, but the planet's gravity also affects the star in turn. "I think a big unknown is whether it has an atmosphere or not", said Johanna Teske, a Carnegie Science researcher and study author. Barnard's star is the fastest moving star in the night sky.
The planet, known as Barnard's star b, is probably dimly lit by its star and slightly colder than Saturn.
There is hope the planet could have a thick atmosphere trapping some heat, but astronomers say it's located beyond the "snow line" where any water on the surface is probably frozen.
The planet candidate, called Barnard's star b (or GJ 699 b), is a super-Earth with a minimum of 3.2 Earth masses.
A slew of telescopes on three continents have set their sights on Barnard's Star, allowing researchers to accumulate some 800 observations over the course of 20 years. The smaller stars tend to send out powerful solar flares and it's thought that flares from Proxima Centauri might regularly sterilize the surface of Proxima b. The timing of the signal indicates that the planet orbits at about the same distance as Mercury orbits our Sun. Teams of semi-professional astronomers coordinated by the American Association of Variable Star Observers also contributed to the detection. "He recognized that this star had the largest known proper motion a century ago".
Professor Carole Haswell, head of astronomy at the Open University and a member of the global team that announced the discovery in the journal Nature, said: "While the starlight from Barnard's Star is too feeble for Barnard's Star b to have liquid water on its surface, Barnard's Star b probably has a similar temperature to Jupiter's moon Europa".
A recent almost-discovery of so-called "super Earth" could change that. The research pushed the limits of the radial velocity detection technique, which becomes more hard the farther a planet is from its star. Most exoplanets, including the thousands identified by NASA's recently retired Kepler space telescope, were found using the "transit" technique: looking for a periodic dip in starlight as a planet passes in front.
"Difficult detections such as this one warrant confirmation by independent methods and research groups", he said in an essay accompanying the new study.
They did this by using observations by the Calar Alto Observatory in Spain using the radial velocity technique. It worked only for the nearest stars and was achieved by taking photographs of the star and measuring its positions in relation to one another.
Might that have happened at Barnard's star? We don't want another van de Kemp scenario.
She said: "After very careful analysis we are over 99% confident that the planet is there".