The Milky Way’s Sun-Facing Spiral Is Bigger Than We Thought

The spiral arm of our galaxy that is closest to the Sun stretches for approximately 20,000 light years, significantly larger than previous estimates.

AsianScientist (Oct. 3, 2016) – The spiral arm of our galaxy that is closest to the Sun—the Local Arm—is significantly longer than previously thought, according to findings published in Science Advances.

The idea that the Milky Way is a spiral galaxy was mooted more than one and a half centuries ago. In the 1950s, scientists began identifying some spiral arm segments, and since then, many models of the galaxy’s structure have been proposed.

Yet, only in the last decade have astronomers been able to accurately measure the distances to these high-mass, star-forming regions, due to the vast distances (up to about 60,000 light years) involved, and interstellar dust that obscures optical observations.

In this study, Professor Xu Ye and colleagues at the Chinese Academy of Sciences, together with collaborators from the United States, Italy, Japan and Germany, report distance measurements for eight regions of massive star formation near the Local Arm of the Milky Way, using a system of radio telescopes called the Very Long Baseline Array.

Combined with previous measurements, these observations reveal that the Local Arm likely stretches for approximately 20,000 light years. Its size is comparable to the galaxy’s major spiral arms, such as Sagittarius and Perseus, rather than being a minor or secondary spiral feature, as previous studies have suggested.

The article can be found at: Xu et al. (2016) The Local Spiral Structure of the Milky Way.


Source: Chinese Academy of Sciences; Photo: Pexels.
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