A new view of 20,000-year old supernova remnant W50 provides more clues to the history of this giant cloud that resembles a beloved endangered species, the Florida Manatee. W50 is nearly 700 light years across, so it covers two degrees on the sky - the span of four full Moons
The W50 cloud formed when a giant star, 18,000 light years away in the constellation of Aquila, exploded as a supernova around twenty thousand years ago, sending its outer gases flying outward in an expanding bubble. The remaining, gravitationally-crushed relic of that giant star, most likely a black hole, feeds on gas from a very close, companion star. The cannibalized gas collects in a disk around the black hole. The disk and black hole's network of powerful magnetic field lines acts like an enormous railroad system to snag charged particles out of the disk and channel them outward in powerful jets traveling at nearly the speed of light. This system of a black hole and its feeder star shines brightly in both radio waves and X-rays and is known collectively as the SS433 microquasar.
Over time, the microquasar's jets have forced their way through the expanding gases of the W50 bubble, eventually punching bulges outward on either side. The jets also wobble, like an unstable spinning top, and blaze vivid corkscrew patterns across the inflating bulges.
Optically bright astronomical objects, those visible to the eye and optical telescopes, often are nicknamed for their earthly likenesses, such as the Whirlpool Galaxy and Owl Nebula. Invisible W50 comes by its less catchy name by being the 50th radio source listed in the Westerhout Catalog, assembled in 1958 by Dutch astronomer, Gart Westerhout.
When the Karl G. Jansky Very Large Array's giant W50 image reached the National Radio Astronomy Observatory Director's office, Executive Assistant Heidi Winter saw the likeness to a manatee, the endangered marine mammals known as "sea cows" that congregate in warm waters in the southeastern United States and the nickname for W50 was born.