most detailed 3D-map of our galaxy is constructed by astronomers of the European Southern Observatory. It turned out that the center of the Milky Way at the same time like peanuts and the letter X.
work was based on publicly available data of observations with ESO VISTA telescope, a wide-angle and measurement of movements of hundreds of very faint stars in the central region of the galaxy – the so-called galactic bulge.
It looks like our galaxy, seen from the side Bulge is a gigantic stellar cloud around the center of the galaxy contains billions of stars, and extends for thousands of light years. However, its structure and origin is not yet fully understood.
Unfortunately, with the center of the Earth’s galaxy could not see very well: her blind us to the dense clouds of gas and dust, which are located between the center of the Milky Way and the solar system.
why astronomers are trying to observe the galactic center at other wavelengths, where dust is invisible.
At the turn of XX-XXI centuries from observations of satellites bulge COBE and infrared view of the sky 2MASS in the center of the galaxy was discovered a strange X-shaped structure. Now, with the help of telescopes, ESO, two groups of scientists discern more clearly the structure of the bulge.
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Group of Institute for Extraterrestrial Physics, Max Planck (Max Planck Institute for Extraterrestrial Physics – MPE) , located in Garching (Germany), using the data VVV (VISTA Variables in the Via Lactea Survey) – this one of the six major sky surveys carried out a wide-angle telescope VISTA (mirror telescope this was done in Russia ). This new survey is open to anyone to use, contains 30 times fainter stars than those that have been reported in earlier reviews bulge. Identified the group a total of 22 million stars that belong to the class of red giants. Well-known physical characteristics of these stars can reliably determine the distance to them. Red giant stellar halo population were chosen objects of study because they can serve as benchmarks for distance determination at the stage of their luminosity giants may be considered independent of their age and chemical composition, and about the same for all the stars. From the observed colors of red giants can directly calculate the amount of gas and dust that blocks light of these stars, and then build the actual distribution of light with the absorption of light gas and dust clouds. And as the population of halo red giants have roughly the same luminosity is true, we thus obtain the estimate of the distance to each of the stars.
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good spatial coverage achieved in the review VVV, possible to carry out such measurements on the entire length of the inner zone of the Milky Way. So it was built three-dimensional map of the galactic bulge.
«The penetration depth of the star catalog VISTA toward the faint stars is much higher than achieved in previous studies of this type. Now we can record the entire composition of the stellar population in all areas of the bulge, except, perhaps, the most heavily shielded by dust, – says Christopher Berry, the lead author of one of the works. – On the basis of these data, we can construct a three-dimensional map of the galactic bulge. This map was first constructed by us without any reference model, which describes the shape of the bulge ».
«We found that the inner region of our Galaxy has a box-like shape, which on one side much like peanuts in the shell, the other – a giant letter X, and the above – an elongated bridge” – adds Ortwin Gerhard, co-author of the first study and head of the research group MPE. The results of this group of scientists accepted for publication in the journal Monthly Notices of the Royal Astronomical Society, with them available online preprints ArXiv.org .
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second international team of scientists led by Chilean graduate student Sergio Vasquez of the Catholic University of Chile in Santiago and ESO chose to study the structure of the bulge is a different approach. Comparing the images obtained on the 2.2 m telescope MPG / ESO interval 11 years, astronomers were able to measure in these pictures microscopic displacement bulge stars, caused by the movement of the stars in space.
By adding the definition of the measurement of the movement of the stars are on the line of sight toward or away from the Earth, scientists have a three-dimensional map of spatial displacements over 400 stars.
radial-velocity measurements made with the FLAMES-GIRAFFE spectrograph on the Very Large Telescope ESO (VLT) and IMACS spectrograph at Las Campanas Observatory. The results of the published in the journal Astronomy & Astrophysics.
«First performed as a mass determination of three-dimensional velocities of individual bulge stars – concludes Vazquez. – It turns out that the stars that we have observed to form along the streams of X-shaped bulge branches, moving with the up and down of the plane of the Milky Way. This is a very good agreement with the predictions of current models! »
Probably our galaxy looks as if seen from above Astronomers believe that the Milky Way was originally simply all-star disc in which billions of years ago formed a flat jumper – the bar. These long, narrow linear structure crossing the central area, there are many galaxies, including our Milky Way. The inside of this jumper then bent and formed the very three-dimensional structure, “Die”, which is found in the current observations.
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