Astronomers have been studying the Milky Way for centuries to better understand its size and structure. And while modern instruments have led to invaluable observations of our galaxy and others (which gave astronomers a general picture of what it looks like), a truly accurate model of our galaxy was elusive.
For example, a recent study by a team of astronomers from National Astronomical Observatories of the Chinese Academy of Sciences (NAOC) has shown that the disk of the Milky Way is not flat (as previously assumed). Because of her findings, it seems that the Milky Way is becoming more and more forgiving and venturing further away from the nucleus.
The study, the results of which were recently published in the scientific journal Nature entitled "An Intuitive 3D Map of Precession of the Galactic Warp, which was followed by classical Cepheids." The study was by Xiaodian Chen of Headed by the NAOC Optical Astronomy Laboratory and comprised members of the Kavli Institute for Astronomy and Astrophysics at Peking University and China West Normal University
Galaxies like the Milky Way are made up of thin slices of stars that revolve around a central bulge once every few hundred million years, in which the gravity of hundreds of billions of stars and dark matter holds Matter and the gas of the galaxy together, into the outer regi On the galaxy, the hydrogen atoms that make up most of the gas disk are no longer confined to a thin plane.
Like Dr. Chen recently stated in a press release by the Kavli Institute:
It is known to be difficult to determine distances from the Sun to parts of the Milky Way's outer gas disk without having a clear idea of what this disk actually looks like. However, we have recently published a new catalog of periodic variable stars, known as classical Cepheids, for which distances can be determined with an accuracy of 3 to 5% . "
Classic Cephieds are a subclass of Cephied Variables, a type of star known for the way it pulsates regularly, both in diameter and in temperature. This results in brightness changes which are predictable in terms of period and amplitude and makes them very useful for the measurement of galactic and cosmic distances.
Classical Cepheids are a special kind of young yellow, light giant and supergiant, 4 to 20 times as massive as our Sun and up to 100,000 times so bright. This means that they have a short lifespan, sometimes only a few million years before the fuel is used up. They also experience pulsations that can last for days or even a month, making them very reliable to measure the distance to other galaxies.
As Dr. Shu Wang of the Kavli Institute for Astronomy and Astrophysics and co-author of On Paper states:
" 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 study, the team created a 3D model of the Galactic Disk, based on the positions of 1,339 classical cephids. From this they could prove that the galactic disc does not coincide with the galactic center. Viewed from above, the disc of the Milky Way would actually appear S-shaped, with one side up and one down.
Professor Richard de Grijs of Macquarie University, a senior co-author of the newspaper, wrote:
"Somewhat to our surprise, we found that in 3D Cepheid Stars and the gas disk of the Milky Way follow each other closely. This provides new insights into the origins of our home galaxy. Perhaps more importantly, we have found in the outer regions of the Milky Way that the S-like star disc is warped in a progressively twisted spiral pattern. "
These results are reminiscent of what astronomers have observed of a dozen other galaxies showing progressively twisted spiral patterns. Combining their results with these observations, the researchers concluded that the spiral pattern of the Milky Way is most likely caused by rotational drive (also called "torque") of the inner disk.
This latest study has provided an updated map of our galaxy's stellar movements that would shed light on the origins of the Milky Way. In addition, it could also improve our understanding of galaxy formation and the evolution of the cosmos.
Bibliography: Kavli Institute of Astronomy and Astrophysics, Nature