WHAT IS BARNARD'S STAR?
Barnard's Star is named after Yerkes Observatory's E.E. Barnard (1857-1923), who discovered it in 1916.
It is close to not being visible to the naked eye, even though at a distance of just six light years it is the second closest star to the Earth - if you consider the three stars of Alpha Centauri system, including Proxima, as a unit.
That is just what you would expect from a dim, low mass, class M (M4) dwarf.
At 3,170 Kelvin (2,896°C / 5,246°F), this dim dwarf has a luminosity 0.0035 times that of the sun, most of the most of it in the infrared end of the spectrum.
These emissions show it has a diameter only 20 per cent that of the sun and a mass 17 per cent of our nearest star.
Far from rare, the great majority of stars fall into the M dwarf category, they are just so faint - like Proxima Centauri - that they are not visible to the naked eye.
Barnard's Star is six light years from Earth - hardly any distance on astronomical scales - a dim dwarf with a luminosity 0.0035 times that of the sun. The only closer star system is Alpha Centauri 4.4 light years away
Barnard's Star is six light years from Earth - hardly any distance on astronomical scales - a dim dwarf with a luminosity 0.0035 times that of the sun. The only closer star system is Alpha Centauri 4.4 light years away
Barnard's Star is old, born before exploding stars had enhanced the amount of interstellar metals to that seen today, with a metal content only 10 per cent that of the Sun.
Its age is also attested to by its long rotation period of 130 days - stars slow down as they age - which is five times longer than the sun's.
Barnard's Star still has some magnetic activity, occasionally popping a flare caused by the release of magnetic-field energy, has an active X-ray corona heated magnetically to two million Kelvin - as does the Sun - and starspots, from which the rotation period is inferred.
Barnard's low internal temperature and resulting feeble energy-generation rate give it an incredibly long life.
Indeed, no class M dwarf ever born in all the history of the Galaxy has ever died.
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