Hubble Images Polaris’s Companion

This sequence of images shows that the North Star, Polaris is really a triple star system.

For the first time, the close companion of Polaris has been seen directly.

The left frame shows Polaris's location very close to the position of Earth's north celestial pole in Ursa Minor (the Small Bear).

The upper right image shows Polaris A and its distant companion Polaris B, as viewed by Hubble. They are separated by approximately 240 billion miles. Polaris B, the wide companion, is visible in small telescopes, and was first noticed by William Herschel in 1780. The close companion, Polaris Ab was known to exist from its gravitational tug on Polaris A, but has only been seen directly now using Hubble (lower right image). The companion is only 2 billion miles from Polaris A.

The triple system is 430 light-years away.

About the data

The Hubble image was created from HST data from proposal 10593 : N.R. Evans (Harvard Smithsonian/CfA), H.E. Bond (STScI), G. Bono (INAF, Osservatorio Astronomico di Roma), M. Karovska (Harvard Smithsonian/CfA), E. Nelan (STScI), D.D. Sasselov (Harvard University), and G. Schaefer (STScI).