EIU Astro

Movie of Chi Cygni pulsating over 408 days December 21, 2009

At a distance of 550 light years away, Chi Cyni is a classic example of a red supergiant, and a variable star. It’s the last stage of a star that has exhausted it supply of Hydrogen in its core and has started to burn Helium. When its diameter is a minimum at 300 million miles, the star’s surface becomes splotchy  with bright spots of hot plasma boil to its surface.  Then, as it expands, Chi Cygni cools and dims, growing to a diameter of 480 million miles. The new images taken by the now closed IOTA (Infrared Optical Telescope Array) where arranged as a movie of the pulsating star, and shows that the pulsation is not only radial, but comes with inhomogeneities, for example, a giant hotspot that appeared when the star approaches minimum.

The IOTA, was a Michelson stellar interferometer located on Mt. Hopkins in southern Arizona. It operated with three 45 cm collectors that can be located at different stations on each arm of an L-shaped array (15 m X 35 m) and reaches a maximum baseline of 38 m. These IOTA pictures have 15 time the resolution of the Hubble space telescope.