Red dwarfs are stars more or less like the Sun - in that they fuse hydrogen into helium in their cores to generate energy - but they are smaller, dimmer, lower mass, and cooler.
Barnard's star b is the second closest known exoplanet to our Sun.
The planet was found using a technique called the radial velocity method that uses sensitive instruments to detect tiny wobbles of the star created by the orbiting planet's gravity.
In the absence of an atmosphere, the planet's temperature is likely to be about -150 ºC, which makes it unlikely that the planet can support liquid water on its surface.
These issues provide an intriguing backdrop for today's announcement that one of the closest stars to Earth has a super-Earth companion.
"Exoplanets so small and so far away from their parent star have not been discovered before using the Doppler technique", says Ribas.
Barnard's Star has always been "the great white whale" of exoplanet hunting, said Carnegie astronomer Paul Butler, a co-author on the Nature paper. The planet, Proxima Centauri b, is just 4.2 light years from Earth. Barnard's star, which is just six light-years away, moves in Earth's night sky faster than any other star.
The star it orbits is called Barnard's Star. When the planet moves closer to the star, the starlight is shifted toward shorter, blue wavelengths (called blueshift) and when the planet moves farther away from the star, the starlight shifts toward longer, red wavelengths (called redshift). This is because it's moving quickly in relation to the sun, and it's the nearest single star in the sky to us, Butler said. But unless you observe a star regularly, there's a chance you won't happen to be looking at critical points in the planet's orbit. But nevertheless, the sheer number of observations builds a fairly compelling case that the planet is there.
Researchers hope to study the planet using a variety of instruments that would allow for direct observations. "Hopefully, we got it right this time", said Guillem Anglada Escude from Queen Mary's School of Physics and Astronomy. "Only when we had done that did the signal become very clear and obvious".
However, if the planet has a substantial atmosphere the temperature could be higher and conditions potentially more hospitable. While not yet strong enough to rule out a false detection, the researchers figured out what it would mean anyway: a Neptune-sized planet orbiting slightly closer than Jupiter orbits in our Solar System. It is worth noting, however, that the measurements place the planet at a similar period to van de Kamp's claims in the 1960s.
"It is the most common type of star in the galaxy-over 70 percent of Milky Way stars are like this dim, M dwarf star", Vogt said.
He added: "Difficult detections such as this one warrant confirmation by independent methods and research groups. a signal for the planet might be detectable in astrometric data - precision measurements of stellar positions - from the Gaia space observatory that are expected to be released in the 2020s".
Astronomers take advantage of this effect to measure the changes in a star's velocity due to an orbiting exoplanet - with astounding accuracy.