The Milky Way's Sagittarius arm spirals out from our galaxy's center. It forms a narrow highway of gas that spans thousands of light-years.
The highway is lined with billions upon billions of stars' headlights, seemingly all moving along the same curvey track. Astronomers have discovered something new: a "break" in the arm that cuts perpendicularly through spiral, much like a splinter poking into a piece wood.
This stellar splinter, which spans approximately 3,000 light years, is just a fraction the size of the Milky Way (which has an approximate diameter of around 100,000 light-years).
According to a July 21 online study in Astronomy & Astrophysics, the newfound break was the first to be found that disrupts the galaxy's seemingly unidirectional flow.
"This structure is a small piece of the Milky Way, but it could tell us something significant about the galaxy as a whole," study co-author Robert Benjamin, an astrophysicist at the University of Wisconsin-Whitewater, said in a statement.
"Ultimately, this is a reminder of how many uncertainties surround the large-scale structure and that we must look at the details if our goal is to see the bigger picture."
(NASA).
Above: A contingent of stars, and star-forming cloud were found sticking out from the Milky Way’s Sagittarius Arm. The inset displays the structure's size and its distance from the Sun. Each star shape is an indication of star-forming areas that could contain dozens to thousands if stars.
The splinter, also known as a spur, or a feather, begins approximately 4,000 light years from the sun. It falls in a famous section of Sagittarius' arm. This region is home to four well-known nebulae, the Omega Nebula and the Trifid Nebula.
Astronomers were unaware of any problems in the area despite its telescope-friendly views until they compared data from two star surveys.
The new study was based on data from NASA's Spitzer Space Telescope and the European Space Agency’s Gaia satellite. It examined the velocity (essentially the angle of the spiral arms curve) in various parts of the Sagittarius arm.
The pitch angle for the main arm was approximately 12 degrees. However, the pitch angle for the section containing break was 60 degrees. It poked almost perpendicularly into the arm.
The splinter's unusual, jutting angle was not the only thing that stood out. The break had hundreds of thousands stars moving in the same direction and velocity as each other, suggesting that they likely formed around the same time and were influenced by the exact same gravitational forces.
This means that an external force pulled the nebulae in a straight line across the flow of the Sagittarius arm.
These young stars are upstarts. What made them rise above the rest? Without additional data, it's difficult to know.
Researchers said that spur- and feather-like structures were common in distant spiral galaxies. The closer we look at the Milky Way, the more likely it is we will find more bits, bobs and breaks like this one.
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Live Science originally published this article. You can read the original article here.
