XMM imaging of variable emission from Alpha Cen A
Credit: Image courtesy of Robrade, Jan and ESA

The Dimming of the Twin

Alpha Centauri is a nearby stellar system consisting of a cool main sequence star (Alpha Centauri B) and a hotter star (Alpha Centauri A), which is nearly a twin of our Sun. Both Alpha Cen A and Alpha Cen B are X-ray sources. The image on the left, obtained by the XMM-Newton X-ray observatory in March 2003, clearly shows X-ray emission from Alpha Cen A (upper left) and B (lower right), and shows that Alpha Cen B is much brighter in X-rays than Alpha Cen A. XMM-Newton again observed the system in February 2005, and surprisingly, Alpha Cen A has disappeared, as shown in the image on the right. This variation may be similar to the solar activity cycle in which the Sun's X-ray emission increases and decreases every 11 years.

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Page Author: Dr. Michael F. Corcoran
Last modified Friday, 20-Apr-2012 15:27:16 EDT