The brightening of Nova Aquila was first detected by optical astronomers in December 1999. Although this star is at a distance of more than 6,000 light years, it could be seen with the naked eye for about a month, during which it was about 100,000 times brighter than our own Sun. An international research team used the Chandra X-ray Observatory to get a better look at this nova. A nova occurs when a white dwarf star that is orbiting a normal-sized star suddenly becomes thousands of times brighter. The team observing Nova Aquila found two strange things: a gigantic burst of X-rays from the white dwarf star, and also that the white dwarf is pulsing at a regular interval of 40 minutes. “Nothing like this has been seen before from a nova, and we don’t know how to explain it,” said team leader Sumner Starrfield of Arizona State University. But scientists hope the findings will help them better understand the thermonuclear explosions that occur in some binary star systems. The research team included Jeremy Drake and Yousaf Butt of the Harvard-Smithsonian Center for Astrophysics.