Recently, astronomers have mapped the most accurate 3-D map of the Milky Way so far. According to the Guardian, what we used to think of as a smooth disc of the Milky Way was actually curved and distorted.
Reuters reported on August 2 that the map clearly shows the overall structure of the Milky Way: composed of four spiral branches and a strip of core area. The disk is about 14,000 light-years in diameter (about 1260 billion kilometers) and is not flat, but curved and of varying thickness. The maximum thickness can be calculated from the center of the galaxy.
The British Broadcasting Corporation (BBC) reported that the researchers published the maps in the Journal Science on August 1. Previously, a widely circulated map of the galaxy was based on 2.5 million stars in the galaxy, and the galaxy disk on the map was smooth. Dr. Dorota Skowron, of the University of Warsaw, said that little is known about the structure and history of the galaxys interior, partly because it is difficult to measure our distances from stars outside the galaxy.
To get a more precise map, Dr. Skowwarren and his colleagues measured the distance between the Earth and some Cepheid variable stars. Dr. Scott Warren was quoted by Reuters as saying: There is a reason to choose Cepheid variables as the best object for rendering. On the one hand, they are the brightest stars in the Milky Way, which are 100 to 10,000 times brighter than the sun. Their existence gives us a picture of the edge of the Milky Way. On the other hand, they are younger and generally form no more than 400 million years, so we can find them around their birthplaces.
The Guardian interviewed Prof Richard de Grijs of Macquarie University, one of the early researchers of Cepheid variables. He said the galaxys curvature may be due to several reasons, including its overlap with other small galaxies, or to the fact that the edge of the galaxy is less gravitationally attracted by the center and is more susceptible to the gravitational pull of other nearby galaxies, thus distorting its overall shape. Dr. Skowullen also said that no distortion was found in the core region of the galaxy, because the gravitational pull of the core region was so great that stars and gases could hardly escape from the Galactic plane.
According to Reuters, the Big Bang 13.8 billion years ago marked the formation of the universe. Shortly thereafter, the Milky Way formed, while the solar system, 26,000 light years away from the black hole in the galaxys center, was formed 4.5 billion years ago.
Source of this article: Peng Mei News Responsible Editor: Zhang Xianchao_NN9310