Imagine standing in a dense forest. How would you know the size and shape of that forest from your limited viewpoint? Not looking at the woods for trees is a good analogy for what astronomers experience when they try to estimate the size and shape of our galaxy – we take a small star system embedded Inside disk of the Milky Way. It's not that we can fly above the galactic plane to look into the overall shape of our galaxy (though it would be cool?).
The researchers, however, were determined to discover the true shape of the Milky Way while they were incorporated into it. Here's how they did it: A team from the National Astronomical Observatory of the Chinese Academy of Sciences (NAOC) and the Macquarie University in Australia studied 1,339 great pulsating stars called Cepheid Variables to create a 3-D map of our galaxy's disc.
What they found came as a surprise: we live in a distorted galaxy.
"We usually think spiral galaxies are fairly straightforward, like Andromeda you can easily see through a telescope," said astronomer and research associate Richard de Grijs at the Macquarie University. But our galaxy is not like Andromeda. It has a S-shaped curve that extends more and more away from the galactic center. In this turn, the gravitational pull of the galaxy becomes weaker, which makes it look like an old vinyl record that has become devastated.
The study, which was published in Nature Astronomy, used data from NASA's Infrared Survey Explorer (WISE) to accurately determine the location of Cepheids on our galactic disk and turn it into a powerful powder-breaker. , gas and other stars that obscure our view.
"It is known that it is difficult to determine the distance from the Sun to the parts of the external gas disc of the Milky Way without a clear idea of how this disc actually looks," said Chen Xiaodian, NAOC researcher and lead author of the study, a separate press release. "However, we recently published a new catalog of well-processed variable stars known as classical cefeids, for which a distance of 3 to 5 percent can be determined."
Cepheids are young stars that are four to twenty times greater than the mass of our Sun, and they live fast and die young, consuming all their fuel in a span of only a few million years, burning up to 100,000 times brighter than our star. But what they lack in their lifetime are compensated for by the regular brightness pulses that astronomers can use to accurately measure distances and, in this case, act as markers for mapping the distorted disc of the Milky Way.
Although the Milky Way is not in accordance with the standard, flat disk of other spiral galaxies (like Andromeda), it is not alone. Based on earlier observations, the researchers identified a dozen other galaxies with a similar form of S-bending, which gave them a clue as to why our galaxy was distorted.
"By combining our results with those other observations, we have concluded that the distorted spiral pattern of the Milky Way is most likely caused by" torque "- or by rotational forcing – from a massive internal disk," added Liu Chao, co-author of the study. Basically, orbital movements in the massive central region of the Milky Way gravitatively maltreate the less massive outer regions, causing them to get out and form a bend.
In the end, this new finding would help us better understand the dynamics of orbiting the Milky Way, giving an insight into the evolution of our galaxy.