Posted: Wed, Jan 11, 2006, 5:52 AM ET (1052 GMT)
Astronomers using the Hubble Space Telescope said this week that they have seen for the first time a small companion star to Polaris. The existence of the star, named Polaris Ab, had been inferred through a detection of a gravitational wobble in Polaris, a supergiant variable star 430 light-years from Earth. The dwarf companion star had not been seen before now, though, because it orbits two billion kilometers from Polaris, a separation of less than 0.2 arcseconds as seen from Earth. Astronomers plan to observe Polaris Ab over the next several years to plot its orbit and determine the mass of Polaris itself. The discovery makes Polaris a triple-star system; a more distant dwarf companion, Polaris B, was discovered over 200 years ago.
