For centuries, astronomers have studied the Growth Path to gain a better understanding of its size and structure. And while modern instruments have provided invaluable observations of our galaxy and others (which have allowed astronomers to get a general idea of what it looks like), a truly accurate model of our galaxy has been a deterrent.
For example, a recent study by a team of astronomers from The National Astronomical Observatories of Chinese Academy of Sciences (NAOC) have shown that Growth Disc is not flat (as previously believed). Based on their results, the Weight appears to be more and more curled and twisted further away from a venture from the core.
The study, which detailed their findings, was recently published in the scientific journal Nature, titled "An intuitive 3D map of the galactic warp's precession of the classic Cepheids." The study was led by Xiaodian Chen of NAOC's Key Optical Astronomy Laboratory and included members of the Kavli Institute of Astronomy and Astrophysics at the Beijing University and China's West Normal University.
To break it down, galaxies like the Winter Road consist of thin discs of stars orbiting a central bulge once every few hundred million years. In this bulge, the gravity of hundreds of billions of stars and dark stock holds the galaxy case and gas together. However, in the outermost regions of the galaxy, the hydrogen atoms that make up most of the gas disk are no longer limited to a thin plane.
As Dr. Chen explained in a recent Kavli Institute press release:
"It is notoriously difficult to determine distances from the sun to parts of Milky Way's outer gas disc without having a clear idea of what that disk really looks like. However, we have recently published a new catalog of periodic variable stars known as classic Cepheids, for which distances are as precise as 3 to 5% can be determined. "
Classic cephieds are a subclass of Cephied Variables, a type of star known for the way it regularly pulses, varying in both diameter and temperature. This generates changes in brightness that are predictable in terms of period and amplitude and makes them very useful for measuring galactic and cosmic distances.
Classic Cepheids are a particular type of young yellow bright giants and supergiants that are 4 to 20 times as massive as our Sun and up to 100,000 times as luminous. This means that they have short lifetimes, which sometimes only last a few million years before exhausting their fuel. They also experience pulsations that can last days or even a month, making them very reliable for measuring distances to other galaxies.
As Dr. Shu Wang, from Kavli Department of Astronomy and Astrophysics and co-author on the paper stated:
"Much of our Milky Way is hidden by dust, making it difficult to measure the distance to stars. Fortunately, observations at long infrared wavelengths can circumvent this problem."
For their investigation, the team established a 3D Galactic Disk model based on the positions of 1,339 Classical Cephieds. From here, they could provide strong evidence that the galactic disk is not in conformity with the galactic center. In fact, when viewed from above, the milk path's disk will be S-shaped, with one side curved up and the other curved down.
Said Macquarie University's Professor Richard de Grijs, a senior co-author on paper:
"Something to our surprise, we found that our Cepheid stars and Melkevej's gas disc in 3D follow each other closely. This gives new insight into the formation of our home calves. Perhaps more important, in the outermost regions of growth, we found that -like star disc is curled in a progressively twisted spiral pattern. "
These results recall what astronomers have observed by a dozen other galaxies that showed progressively twisted spiral patterns. By throwing their results with these observations, the researchers concluded that the spiral pattern of growth is probably due to the rotational strength (aka "Torques") on the inner disk.
This latest study has provided an updated map of our galaxy stellar movements that would shed light on the origin of the Milky Way. In addition, it can also inform our understanding of the galaxy formation and the development of the cosmos.
Further reading: Kavli Department of Astronomy and Astrophysics, Nature