The arrival of the James Webb Space Telescope cannot come soon enough.
Astronomers have discovered a previously unknown feature of our Milky Way galaxy: a cluster of young stars and star-forming gas clouds jutting from one of the galaxy’s famous spiral arms “like a splinter coming out from a plank of wood.” With each new discovery, we’re gradually revealing the secrets of the cosmos and learning more about how we came to be.
The structure is said to extend roughly 3,000 light-years out from the Sagittarius Arm, and was discovered using NASA’s (now retired) Spitzer Space Telescope along with data from the European Space Agency’s Gaia mission. It features four nebulae: the Eagle Nebula, the Omega Nebula, the Trifid Nebula and the Lagoon Nebula.
Michael Kuhn, an astrophysicist at Caltech and lead author of the study, said a key property of spiral arms is how tightly they wind around a galaxy. “Most models of the Milky Way suggest that the Sagittarius Arm forms a spiral that has a pitch angle of about 12 degrees, but the structure we examined really stands out at an angle of nearly 60 degrees.”
The feature itself, known as a spur or feather, is not particularly unusual, as it has been observed in other spiral galaxies. But, given Earth’s position inside the galaxy, making important discoveries like these about the Milky Way is exceedingly difficult (in the Orion Arm). “It’s like standing in the midst of Times Square and attempting to draw a map of the island of Manhattan,” NASA explained in a blog post.
The discovery, according to another of the paper’s co-authors, Robert Benjamin, is a reminder that there are many unknowns about the Milky Way’s large-scale structure. “This structure is a small piece of the Milky Way, but it could tell us something significant about the galaxy as a whole,” he added.
The team’s paper can be read in the international journal Astronomy & Astrophysics.
Image credit Jeremy Thomas