Our Galaxy is half proved less massive than previously anticipated
Based on 2500 data speeds of stars in our Galaxy, obtained during the investigation Sloan Digital Sky Survey (SDSS), members of the National Astronomical Observatory in Beijing calculated that the mass of the Milky Way twice lower than anticipated so far. According to estimates of scientists, the total mass of the galaxy is just under 1 trillion solar masses.
Earlier studies relied on a smaller statistical sample: scientists have tried to calculate the mass of the Milky Way, based on data on the movement of tens to hundreds of stars. Moreover, the mass of the Galaxy tried to calculate on the basis of data on the treatment dwarf galaxies - Milky Way satellites. The results also showed that the mass of our Galaxy is about 2 trillion solar masses.
However, more recent studies have shown that the gravitational "grip" on his Milky Way satellite galaxies is less than one should expect, and explain that astronomers could not.
The staff of the Beijing National Observatory, as already mentioned, studied the motion of stars 2500, located at a distance of 13 to 200 thousand light years from the center of the Milky Way. Solar system, to say the word, is located at a distance of about 25 thousand light years from the center of the Galaxy.
Using collected under the programme SDSS data on the spectrum of each of these stars, astronomers were able to calculate the speed of their movement on the Earth. Comparing these figures with data on the motion of stars in other galaxies with different masses, astronomers have been able to clarify the mass of the Milky Way. As it turned out, it is about 0.93 trillion solar masses, however, the degree of error in the calculations, for the recognition of the researchers, may be up to 0.25 trillion masses.
Update data will be after the third round programme SDSS, which will provide data on the stars located at a distance of more than 300 thousand St. years from the center of the Milky Way.