The Milky Way is “warped and twisted” and not flat
The Milky Way is “warped and twisted” and not flat as previously thought, according to researchers who have developed a large-scale three-dimensional (3D) map of our galaxy. By measuring the distance from the Sun to thousands of individual pulsating stars scattered across the Milky Way, the researchers have charted the galaxy on a larger scale than ever before.
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Their new three-dimensional map, published in the journal Science, provides a broad view of our place among the stars.
The map reveals the S-like structure of the Milky Way’s warped stellar disc.
“Our map shows the Milky Way disk is not flat. It is warped and twisted,” said Przemek Mroz, from the University of Warsaw in Poland.
“This is the first time we can use individual objects to show this in three dimensions,” Mroz said.
Much of the current understanding of the spiral shape and structure of our galaxy is built upon indirect measurements to celestial landmarks and inferences based on other galaxies in the universe.
However, the galactic map drafted by those limited observations remains incomplete, researchers said.
Like so many lighthouses on distant foggy shores, classical Cepheid variable stars — massive young stellar bodies that burn hundreds, if not thousands of times brighter than our own Sun — pulsate at regular intervals and are visible through the vast clouds of interstellar dust that often obscure dimmer stellar bodies.
Using the periodic variations in their brightness, researchers said the distances to these stars can be precisely determined.
Dorota Skowron from the University of Warsaw and colleagues charted the distance to more than 2,400 Cepheids throughout the Milky Way.
Most of the Cepheids were identified by the Optical Gravitational Lensing Experiment (OGLE) — a Polish astronomical project that more than doubled the number of known galactic classical Cepheids.
By determining the 3D coordinates of each distant pulsing star relative to our Sun, Skowron and colleagues built a large-scale 3D model of the Milky Way galaxy. The new map illustrates and helps constrain the previously observed shape of the galaxy’s warped stellar disc.