Cosmology isn’t just about the Big Bang and the birth of galaxies. It’s also about death, such as the dying of stars. For the first time, observations taken at the Smithsonian Astrophysical Observatory’s Infrared Optical Telescope Array, or IOTA, which is located at Whipple Observatory on Mount Hopkins, Arizona (USA) have revealed the final phase of the star Chi Cygni about 550 light-years from Earth.
Though gigantic in size, this sun is so distant that individual telescopes – even ones as powerful as the Hubble – are not able to reveal much detail. However, by combining the observations from several telescopes, in a process called interferometry, a much clearer picture can be achieved. Chi Cygni is especially interesting because it is (or was) very much like the Sun in our solar system. It has now entered the final phase of its life cycle known as a ‘red giant,’ a ball of fiery fusions that expands and contracts on the scale of a hundred million miles in diameter.
Chi Cygni pulses once every 408 days. At its smallest diameter of 300 million miles, it becomes mottled with brilliant spots as massive plumes of hot plasma roil its surface. (Those spots are like the granules on our Sun’s surface, but much larger.) As it expands, Chi Cygni cools and dims, growing to a diameter of 480 million miles – large enough to engulf and cook our solar system’s asteroid belt.
For the first time, astronomers have photographed these dramatic changes in detail. They reported their work in the December 10 issue of The Astrophysical Journal.
“We have essentially created an animation of a pulsating star using real images,” stated Lacour. “Our observations show that the pulsation is not only radial, but comes with inhomogeneities, like the giant hotspot that appeared at minimum radius.”
[Source: Harvard University]
If it were our own Sun, the expansion would reach all the way to the asteroid belt between Mars and Jupiter – swallowing Mercury, Venus, Earth, and Mars in the process. About five billion or so years from now, this will be the fate of the Earth, which is why watching the process in another star holds particular interest.