A new map of the Milky Way shows that the spiral arm that contains our solar system is much larger than previously believed.
New Scientist reports that a group of scientists from the Purple Mountain Observatory in Nanjing, China discovered evidence that our Milky Way neighborhood is just as bulky as comparable areas elsewhere in the galaxy.
The solar system has been thought to be located in the spiral structure called the Local Arm, or the Orion Spur, which scientists have believed is much smaller than the neighboring Perseus Arm. Other Milky Way appendages are as bulky as the Perseus Arm, and even those which are sporting fewer stars make up for the lesser star count by containing as much gas as the largest arms.
The solar system’s home arm is now looking like it can keep up in the arm size race thanks to a new comprehensive study of the galaxy’s form.
The research team collected data using the Very Long Baseline Array in New Mexico to map the high-mass clouds in the spiral arms. The team also calculated the clouds’ distances.
“Radio telescopes can ‘see’ through the galactic plane to massive star forming regions that trace spiral structure, while optical wavelengths will be hidden by dust,” Ye Zu of the Purple Mountain Observatory said.
The mapping project revealed a Milky Way that does not have well-defined arms, but rather a number of spiral structures with branches and small spurs.
The so-called Orion Spur in which Earth resides turns out to not be a spur after all, but more like one of the Milky Way’s huge spiral arms. A spur was also found to connect the Local Arm with the large Sagittarius Arm.
“This lane has received little attention in the past because it does not correspond with any of the major spiral arm features of the inner galaxy,” the study authors wrote.
Further efforts are underway to better map our galaxy, including a 3D mapping project with the European Space Agency’s Gaia spacecraft.
The study was published in the journal Science Advances.