A team of scientists using the Subaru telescope identified the extreme edge of the Milky Way – the border of the galaxy's star system. The ultimate size is 520,000 light-years in radius, 20 times larger than the 26,000 light-years between the galactic center and our solar system. The galaxy is so large that it is impossible to identify the halospores located at the outer limit using 2.5 to 4 meter telescopes.
Stars reaching these outermost regions of the galaxy during their orbit are old star stations of ages as old as 12 billion years. The spatial extent to which these ancient stars migrate is important for the understanding of Milky Way's formation.
Astronomers recently discovered that the Libra's star disc is becoming more and more "curled" and twisted further away from the stars from the galaxy center. "We usually think of spiral galaxies as being quite flat as Andromeda, which you can easily see through a telescope," says Professor Richard de Grijs, an astronomer from Australia's Macquarie University who was not part of the Subaru project.
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The galaxy has a broadly expanded halo component in addition to the light milk path in the form of the star disc component. Halo contains about 1 billion old stars and 150 globular clusters of ages as old as 12 billion years (Figure 1). The halo thus contains the remains of long-lived stars and star clusters that formed in the first phase of the Galaxy. This suggests that the galaxy was quite large in the beginning before the later formation of the younger disk component.
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Examine the extent of this halo component in the galaxy resembling the identification of the outer border of a forest inside the forest and observe the trees. In other words, it is a difficult task. So-called Blue Horizontal Branch (BHB) stars as well as RR Lyr variables are ideal indicators for tracking the halo component. This is because they are naturally bright enough to determine the distance to and from them.
The research team led by Tohoku University graduate student Tetsuya Fukushima and his indicative Masashi Chiba used Hyper Suprime-Cam (HSC) digital camera at 8.2 meters diameter Subaru Telescope. It allowed them to capture distant, very weak halo trace elements on the outer edge of the Galaxy. The team carefully selected the BHB stars from the ongoing study program (SSP: Subaru Strategic Program) data against other pollutants of similar colors such as so-called blue straggler stars, white dwarfs, quasars and distant galaxies.
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Using data from HSC-SSP, the team derived the spatial density of the BHB stars over the galaxy halide. While this density generally decreases the further you go from the galactic center, the team discovered a sharp drop in density of about 520,000 light-years away from the galactic center. Thus, the team had finally observed the outermost edge of the galaxy. This is approx. 20 times greater than the distance between our solar system and the galaxy center.
"mashup" -Massive Antique Collision & # 39; Puffed and Fractured & # 39; the Milky Way
12 billion years ago, successive fusion of small galaxies limited by dark matter halogens occurred. The key to understanding this is to measure the distribution of the halo component to determine the volume. This fusion process differs from galaxy to galaxy. Our neighbor, the Andromeda Galaxy, is reported to have an extended halo component as large as 538,000 (at least) light years in the radius. It is systematically greater in relation to the galaxy halo. The researchers plan to further map this ancient galaxy component after the final implementation of the HSC-SSP.
"Huge Ghost Galaxy" -Hidden in the Milky Way & # 39; Zone of Avoidance & # 39;
Daily galaxy via Subaru Telescope