ESA's XMM-Newton has spotted surprising changes in the powerful streams of gas from two massive stars in the binary star system HD 5980. One of the two stars had a major outburst reminiscent of the 19th-century eruption of Eta Carinae, and astronomers expected that its X-ray emission would fade gently over the years. Instead, they found the pair was two and a half times brighter than a decade earlier, and its X-ray emission was even more energetic, suggesting that colliding stellar winds don’t behave as expected.

Full story: Stellar winds behaving unexpectedly