BG Indi

Did You Know?

• BG Indi is its variable star designation, a unique name given to variable stars based on its constellation.
• The system also bears the Bayer designation κ1 Indi (Latinized to Kappa1 Indi).

Properties

BG Indi is a quadruple star system made up of four stars arranged in two close-orbiting pairs. The brighter pair, BG Indi A, contains two F-type main-sequence stars called Aa and Ab. These stars are bigger, heavier, and hotter than the Sun, though they have a lower metallicity of -0.2 plus or minus 0.1. The whole system is roughly 2.65 billion years old and has just begun to move away from the main sequence. Stars Aa and Ab circle each other in a circular orbit every 1.46 days, and because they periodically eclipse one another, the system's apparent brightness shifts between 6.11 and 6.36. This eclipsing binary nature was confirmed in 1984 by J. Manfroid and G. Mathys. The other pair, BG Indi B, consists of stars Ba and Bb, both less massive than the Sun, which orbit each other even more tightly with a period of 0.53 days. The two pairs themselves orbit a common center of gravity every 720.9 days on a moderately elliptical path with an eccentricity of 0.209. All three orbits are thought to be roughly aligned in the same plane. BG Indi is the closest known quadruple star system that contains two eclipsing binaries.