Astronomers capture close-ups of a sun-like star dying

A dying star named Chi Cygni, about 550 light-years away, is flashing close-up, infrared glimpses of what our sun's future death throes will look like to observers at a safe distance.

About five billion years from now, Earth's sun will swell into a red giant star like Chi Cygni. engulfing and frying our solar system's inner planets. A team of astronomers with the Harvard-Smithsonian Center for Astrophysics (CfA) is observing and photographing in detail, the final brightening and dimming sputters of Chi Cygni, a distant star very similar to our sun, while its core continues to run out of fusion-powering hydrogen fuel. Every 408 days, Chi Cygni expands from a diameter of 300 million miles, spotted and roiled with gigantic granules and plumes of hot plasma, then cools and dims to diameter of 480 million miles. If Chi Cygni were swelling in this solar system, it would cook everything out to the asteroid belt. This is the first time astronomers have photographed and recorded a variable star's dramatic shifts in detail, a difficult task because such objects appear tiny at great distances, are hidden by dust and must be observed at infrared wavelengths. Using the Smithsonian Astrophysical Observatory's Infrared Optical Telescope Array (IOTA), located at Whipple Observatory on Mount Hopkins, Arizona, along with observations from amateur astronomers around the world contributed through the American Association of Variable Star Observers (AAVSO), the CfA team was able to use real images to create an animation of a pulsing star. "Our observations show that the pulsation is not only radial, but comes with inhomogeneities, like the giant hotspot that appeared at minimum radius," explained lead author Sylvestre Lacour of the Observatoire de Paris. Co-author Marc Lacasse of the Harvard-Smithsonian Center for Astrophysics (CfA) added that IOTA has allowed the astronomers to see image details 15 times smaller than details resolved in images from the Hubble Space Telescope. Lacour's team has reported this research in the December 10 issue of The Astrophysical Journal.