Credit:Y. Nazé et al.; ESA
Two stars spin around each other in another galaxy, unseen for millenia until spotted by modern instruments. They just happen to revolve in an orbit that's edge on to our line of sight. The stars are some of the most massive we know about and each is so bright its luminance drives off the stuff the star is made of. One is passing through an incredibly brief period of instability when the mass loss changes violently. Even though the event actually happened something like 100,000 years ago, we just saw it about 10 years ago. That's the binary system HD 5980 in the Small Magellanic cloud, composed of two of that galaxy's brightest and most massive stars, one of which is in the so-called Luminous Blue Variable stage. Because the stars are close to each other, material driven off their surfaces collides between them and produces large amounts of extremely high temperature, X-ray emitting gas. The montage above shows XMM-Newton X-ray images of HD 5980 (the bright point of light near the center of each image - the star itself appears surrounded by a foreground, X-ray emitting supernova) at different times in its 20-day orbit. The X-ray emission peaks when the companion is in front of the LBV star. This shows that XMM-Newton is detecting X-ray emission from the collision of the material between the two stars, offering a means to monitor the variable mass loss from the unstable monster.
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Page Author: Dr. Michael F. Corcoran
Last modified Friday, 20-Apr-2012 15:27:17 EDT