Currently, the red dwarf star Proxima Centauri, 4.244 light-years away in the constellation of Centaurus, is the closest star to the Sun. However, around 5.95 light-years away in the constellation Ophiuchus, a star is located, which will “soon” be our new nearest neighbour. This is the story of Barnard´s Star, a red dwarf on the way to our solar system.
Location of Barnard´s Star
Barnard´s Star, also known as Gliese 699, HIP 87937, Proxima Ophiuchi or Barnard´s Runaway Star is currently ~5.95 light-years away from our solar system in the constellation Ophiuchus. This makes the star the fourth nearest star to the Sun after Proxima Centauri, Toliman and Rigil Kentaurus, as well as the second closest star system after Alpha Centauri. However due to its high proper motion, the highest of all known stars, the star is gradually traveling towards our solar system with a speed of 110 km/s. In the year 11,800, Proxima Ophiuchi will have reached its closest distance, at only 3.8 light-years away. After that, the star will start moving away from the Sun again.
The current closest star to Proxima Ophiuchi is the red dwarf Ross 154, also known as V1216 Sgr in the constellation Sagittarius, 9.69 light-years away from Earth and 5.41 light-years away from Barnard´s Star.
Due to its low luminosity, Proxima Ophiuchi is not visible with the unaided eye.
About the star itself
Like our nearest star Proxima Centauri, Barnard´s Runaway Star is a red dwarf star. The star is a main-sequence star which means it uses nuclear fusion to generate energy. However due to its low mass of only 14 percent the mass of our Sun and only 20% the Sun´s radius, Barnard´s Star is much more dimmer and colder than our parent star.
Observations have shown that the star is between 7 and 12 billion years old, which makes it one of the oldest stars in the whole Milky Way galaxy. The Sun for comparison is only 4.5 billion years old.
Proxima Ophiuchi seems to be a flare star like Proxima Centauri, which means the star can have unpredictable increases in brightness, which however only lasts for a few minutes. Such flares can be extremely dangerous for nearby planets, whose potential atmospheres can be destroyed within a relatively short period of time.
Exoplanets around Barnard´s Star
Between 1963 and 1973, many astronomers believed that there is a planet around Proxima Ophiuchi, with the mass of Jupiter. However, papers published in 1973, disproved the existence of the planet the Dutch astronomer Peter van de Kamp claimed to have found.
In November 2018, the detection of another potential exoplanet discovery was announced. However, the claim still has to be confirmed by follow-up observations.
If the exoplanet really exists, it would lie around 0.4 astronomical units away from its parent star. With a mass of 3.2 times the mass of Earth, the planet would most likely be a super-Earth, a huge rocky planet. Because of the low luminosity of the red dwarf and the distance to it, Barnard´s Star b would be extremely could, around -170°C. This would make it very difficult for life to evolve.