Revealing the ‘skeleton’ of the Milky Way

Astronomers have identified a new part of our Milky Way galaxy; a structure they are calling the ‘bone’.

Galactic bones, are long tendrils of dust and gas which radiate out between the arms of spiral galaxies. Computer simulations of how spiral galaxies form have predicted the formation of these structures between spiral disks. Astronomers looking at this type of galaxy have seen these internal skeletons before, but this is the first time a bone has ever been identified in our own Milky Way.

“This is the first time we’ve seen such a delicate piece of the galactic skeleton,” says lead author Alyssa Goodman of the Harvard-Smithsonian Center for Astrophysics.

The bone was discovered by Goodman and colleagues while studying a dust cloud, nicknamed ‘Nessie’ after the Loch Ness Monster. A study of its radio emissions revealed that it was a stable feature, containing about 100,000 suns worth of material. The slender bone is more 300 light-years long but only 1 or 2 light-years wide.

“This bone is much more like a fibula – the long skinny bone in your leg – than it is like the tibia, or big thick leg bone,” says Goodman.

“It’s possible that the ‘Nessie’ bone lies within a spiral arm, or that it is part of a web connecting bolder spiral features. Our hope is that we and other astronomers will find more of these features, and use them to map the skeleton of the Milky Way in 3-D,” she adds.

Earth and our solar system are residents of the Milky Way, made up of a central bar and two major spiral arms that wrap around its disk. Our location within the Milky Way makes it very difficult for astronomers to determine its structure, as we will never be able to look at it from the outside.