Milky Way Streaking

In 2017, astronomers noticed a star streaking out of the Milky Way at nearly 2 million mph (3.2 million km/h) — roughly four times faster than our sun orbits — and flying against the direction in which most stars trek around the galactic center. 

It's also made of completely different star stuff, mostly heavy, "metallic" atoms rather than the usual light elements. 

LP 40-365, as it was called, was as eye-catching as a wooden car barreling up the interstate against traffic at hundreds of miles per hour.

"It is exceptionally weird in a lot of different ways," said study lead author J.J. Hermes, an astronomer at Boston University.

The star moves so quickly that it's headed out of our galaxy for good, which astronomers have taken as evidence that the metallic explorer was launched here by a cosmic catastrophe — a supernova. 

But they couldn't tell how the supernova had sent it flying. Was LP 40-365 a piece of the exploded star itself? Or was it a partner star flung clear by the shockwave associated with star explosions? 

A new analysis of old data finds that the star — called a white dwarf — spins about its axis at a leisurely pace — a hint that it is indeed a piece of stellar debris (not a partner star) that managed to survive one of the galaxy's most violent and mysterious events.

"We can now connect this star to the shrapnel from an exploded white dwarf with a lot more confidence," said Hermes.  READ MORE