[LINK] On the oddity of Nova Vulpeculae 1670, aka CK Vulpeculae

[rfmcdonald]

National Geographic's Nadia Drake reports on how recent reanalyses of an obscure seventeenth-century nova points to early astronomers' observation of something very unusual.

For decades, scientists thought the explosion was a classical nova, a stellar outburst that’s less catastrophic than a supernova. But a new look at the remnant left behind by the explosion reveals a more violent history, astronomers report Monday in Nature. Now called CK Vulpeculae, the explosion was what’s called a red transient, produced when two stars violently collide.

Red transients are thought to be a relatively rare type of stellar smashup; based on the chemical elements produced in the collision, this one appears to have been particularly violent, possibly even head-on, says study author Tomasz Kaminski, of the European Southern Observatory.

In 1670, a new star appeared in the sky. Located near the head of Cygnus the Swan, the guest star was first spotted in June. It stuck around through the summer but faded in the fall.

In March 1671, the star reappeared—and over that summer, it shone brighter than ever before. Astronomers of the time, including lunar cartographer Hevelius and Giovanni Domenico Cassini (the namesake of NASA’s Saturn-exploring Cassini spacecraft), kept track of the star’s light until it vanished that October. It made one more feeble appearance in 1672 before disappearing for good.

At the time, astronomers didn’t know what they were looking at. “There would still have been controversy as to whether the nova was in the starry realms or in the Earth's atmosphere,” says Owen Gingerich, professor emeritus of astronomy and the history of science at the Harvard-Smithsonian Center for Astrophysics.