The Milky Way is our home, but since we’re inside it, it might be the most unfamiliar of galaxies to observe. Recently, astronomers discovered for the first time in the Milky Way that the spiral arms of Sagittarius had broken off, disrupting the regular flow of the Milky Way.
The Milky Way is a beautiful spiral galaxy, comprising 4 main spiral arms, namely: Swan Arm (or Outer Arm, Rectangular Arm), Southern Cross Arm, Sagittarius Arm, Perseus Arm, Interstellar Matter in the Milky Way and hundreds of Billions of stars are scattered over the arms of these galaxies, but the spiral structure of the Milky Way is not fully defined, and the spiral arms often branch, merge and twist. For example, our solar system is located in the arm of the Sagittarius branch – the arm of Orion.
Spiral arms of the Milky Way. (Source: Dragons flight & Surachit (English version), Zanhsieh (translated by zh-hant). CC BY-SA 3.0, via Commons Wikimedia)
One of the ways astronomers map the Milky Way is by measuring the locations and distances of thousands of stars. For example, the main goal of the Gaia satellite is to study the locations and trajectories of more than a billion stars and reveal the details of the structure of the Milky Way.
Another way is to observe certain objects in the Milky Way, such as the nebula that is usually located in the spiral arms of the galaxy with a large amount of gas and dust. The Spitzer Infrared Space Telescope measures the distance of many young stars in the galaxy. The nebula helps us ensure that the Milky Way has 4 main spiral arms.
A new study now combines observational data from the Gaia satellite and the Spitzer telescope to focus on analyzing the general distribution of the Arc Nebula and stars. The first study includes four famous nebulae: the Eagle Nebula (where the Pillar of Creation is located), the Omega Nebula, and three in the Split Nebula and the Lake Nebula, it was discovered that although the main arm’s elevation angle was about 12 degrees as in the past, there is an A regional elevation of 60 °, that is, a structure appeared almost perpendicular to the original spiral arm, the length of which is about 3000 bulbs per year.
The appearance of a broken arm on the horse’s arm. (Source: NASA)
In addition to the strange angle of prominence, hundreds of thousands of stars in the broken arm seem to move with the same speed and direction, which indicates that the stars there were formed at about the same time and are affected by the same gravitational force, is that there is a local external force that removes these nebulae from a long straight line Another was drawn from the arm of a centaur.
The research team does not yet know why these stars separated from their original spiral arms, and the more we look closely, we will likely find similar spiral arms. The new paper was published in the Journal of Astronomy and Astrophysics.
(Image source: NASA)
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