Guardians of the Stars
Epsilon Indi is a star system approximately 12 light-years away from the Earth in the constellation of Indus consisting of a K-type main-sequence star, ε Indi A, and two brown dwarfs, ε Indi Ba and ε Indi Bb, in a wide orbit around it. The brown dwarfs were discovered in 2003. ε Indi Ba is an early T dwarf (T1V) and ε Indi Bb a late T dwarf (T6V) separated by 0.6 arcseconds, with a projected distance of 1460 AU from their primary star.
Epsilon Indi is a main-sequence star of spectral type K4.5V. The star has only about three-fourths the mass of the Sun. Its surface gravity is slightly higher than the Sun’s. The metallicity of a star is the proportion of elements with higher atomic numbers than helium, being typically represented by the ratio of iron to hydrogen compared to the same ratio for the Sun; Epsilon Indi is found to have about 87% of the Sun’s proportion of iron in its photosphere.
The corona of Epsilon Indi is similar to the Sun, with an X-ray luminosity of 2×1027 ergs s−1 and an estimated coronal temperature of 2×106 K. The stellar wind of this star expands outward, producing a bow shock at a distance of 63 AU. Downstream of the bow, the termination shock reaches as far as 140 AU from the star.
Only one planet exists within the Epsilon Indi system and that is a Jupiter analogue which is slightly farther away (another 4 AU) and slightly smaller (90% the mass) than our own systems Jupiter.