Barnard's Star

Ownership: UCP
Spectral class: M5 red dwarf

Barnard's Star is a very low-mass class M5 red dwarf in the immediate neighborhood of the Sol system. The star is also known as Gliese 699.

Although an ancient star, Barnard's Star still experiences flare events.

Overview

At 7 to 12 billion years of age, Barnard's Star may be among the oldest stars in the universe; it has lost a great deal of rotational energy, and periodic changes in its light indicate it rotates just once every 130 days.

Although it is roughly 180 times the mass of gas giant, its radius is slightly larger, reflecting the tendency of objects in the brown dwarf range to be about the same size. Its effective temperature is 3,134(±102) K, and it has a bolometric luminosity of 34.6/10,000ths.

In a broad survey of the metallicity of M dwarf stars, Barnard's Star's was placed between −0.5 and −1.0 on the metallicity scale. Metallicity, the proportion of stellar mass made up of elements heavier than helium, helps classify stars relative to the galactic population. Barnard's Star seems to be typical of the old, red dwarf population II stars, yet these are also generally metal-poor halo stars. Barnard's Star's metallicity is higher than a halo star and is in keeping with the low end of the metal-rich disk star range; this, plus its high space motion, have led to the designation "Intermediate Population II star", between a halo and disk star.