Friday, September 13, 2013

Stars-X in the heart of the Milky Way - scinexx | Knowledge Magazine


So would the Milky Way and its peanut-shaped bulge look from the side
© ESO / NASA / JPL-Caltech / M . Kornmesser / R. Hurt How the Milky Way and its peanut-shaped bulge would look from the side

One of the most important and most massive parts of our home galaxy is called the bulge, a central thickening of the Milky Way. This huge, centralized cloud of about ten billion stars has a diameter of thousands of light years. So far, however, it was not able to understand their structure and origin. Unfortunately, the view from our location in the galactic disk in this central region of dense gas and dust clouds is very limited.

Class=”titel1″> red giants as mapping help
astronomers can only then get a good look at the bulge by observing at longer wavelengths, such as in infrared light can penetrate dust clouds. Previous observations in the 2MASS infrared sky survey had already indicated that the bulge could have a mysterious X-shaped structure. Now, two research groups have gotten a much clearer view of the structure of the bulge against new observations with several ESO telescopes.

Christopher Wegg from the Max Planck Institute for extraterrestrial Physics (MPE) in Garching and his colleagues used VVV near-infrared survey of the VISTA telescope at ESO’s Paranal Observatory in Chile. This new screening can detect thirty times fainter stars than previous surveys. The team of astronomers has identified for a total of 22 million stars that belong to a subclass of the red giant and its well-known properties allow it to determine their distances. This then astrono mers could put together a three-dimensional map of the bulge structure.



The 3.6-meter ESO telescope at La Silla ago the Milky Way
The 3.6-meter ESO telescope at La Silla in front of the Milky Way
© ESO / S. Brunier The 3.6-meter ESO telescope at La Silla in front of the Milky Way

peanut and bars in a
“It is the first time that such a card without the assumption of a model for the shape of the bulge could be created, “said Wegg. The results showed that resembles the inner region of our galaxy from the side of a peanut, wrapped in their shell. From above, however it looks more like an elongated beams. Similar peanut-shaped structures were already in the bulges of other galaxies observed. Their formation can be calculated in advance with computer simulations, which show that the peanut shape of stars is formed, which arrange themselves in an X-shaped structure.

addition to this focused the second research team led by Sergio Vásquez of the Pontificia Universidad Católica de Chile to the movement of the stars in the bulge -.., and thus its dynamic structure, determined this by comparing images of the MPG / ESO 2.2-meter telescope, which were created at a distance of eleven years enabled them to the movements mapping of more than 300 stars in three dimensions.

class=”titel1″> star trek in the X
“It is the first time that such a large number of could determine velocities in three dimensions for individual stars from both sides of the bulge, “Vásquez summarizes.” the stars that we have observed appear to migrate along the arms of an X-shaped bulges, while their orbits it up and down while carry out even from the plane of the Milky Way. “

The astronomers assume that the shape of the Milky Way has only emerged gradually. Initially a disk of stars, they developed billions of years ago a flat bar . Meanwhile, inner part arched and then took on the three-dimensional, peanut shape, which can be seen in the new observations.

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