The loss of two arms Milky Way.
For decades astronomers have been blinded by the appearance of the Milky Way. How so? Milky Way does not look like what we imagined and portrayed over the years. Can not blame because we live in it, and never get out to see how it looks.
A new image from NASA’s Spitzer Telescope a reality another drain on the structure of the Milky Way. From the known galaxy image has only 2 instead of 4 spiral arms spiral arms as we saw earlier.
Spitzer gives a new starting point for rethinking the structure of the Milky Way, said Robert Benjamin of the University of Wisconsin, Whitewater. Revised map of the Milky Way will be performed throughout the world and, as a sailor who was wandering in the sea in ancient times, they also constantly update their maps.
Since 1950, astronomers have created a map of the Milky Way. The early models were based on radio observations of gas in the galaxy. The result is a spiral structure with four major star-forming arms, called Norma, Scutum-Centaurus, Sagittarius and Perseus. In the Milky Way, in addition there is also a ribbon arms of gas and dust at the galaxy’s center. Our sun lies near a small, partial arm called the Orion Arm, or Orion Spur, located between the Sagittarius and Perseus arms.
Over the years, the map of the whole galaxy based on studying just made a part of the galaxy or just one method. And when the models from various groups were compared, they did not always agree with each other. Just as the blind an elephant from different facets. That is us. The researchers see the Milky Way from different sides so that when confronted course the outcome was different.
But in the era of 1990, large infrared sky surveys, brings a fresh new look. Massive sky survey at infrared wavelengths carrying a major revision to the model including the discovery of a large galaxy in the Milky Way that contains the stars. Infrared light can penetrate through dust, so telescopes designed to observations at infrared wavelengths can have a better vision between the centers of galaxies are dusty and crowded with a variety of objects.
In 2005, Benjamin and his colleagues used Spitzer’s infrared detectors to obtain detailed information about our galaxy. They found that it extends from the Galactic center to the outside is wider and longer than previously thought.
New infrared image of the Milky Way galaxy shows, stretching 130 degrees across the sky and one degree of stretch of the galactic plane toward the top and bottom. This extensive mosaic combines 800,000 snapshots and includes over 110 million stars.
Benjamin developed software that counts the stars, measuring stellar densities. Calculations he did on the Scutum-Centaurus arm showed an increase in numbers, as would be expected for a spiral arm. While measurements of the Sagittarius and Norma arms did not show an increase in the number of stars. In the arm-4 the Perseus arm covering the outer Milky Way can not be seen in the latest images taken by Spitzer.
The discovery that the Milky Way has two major spiral arms, a common structure for galaxies with bars. The main arm is the Scutum-Centaurus and Perseus arms, have the greatest densities of both young, bright stars, and older as a red giant star. The two other arms, Sagittarius and Norma arms as minor arm consisting of gas and young stars. Benjamin said the two major arms seem to connect up nicely with the near and far ends of the main. Thus, the arm can be connected with the bar, like installing a puzzle, so for the first time can map the structure, position and width of these arms.
The discovery Previous infrared observations found hints of both the arm. But the results were unclear because the position and width of the arms were unknown. Though galaxy arms appear to be intact features, but in reality the stars in it are constantly moving in and out on the arm. This is caused by the movement of the stars as they orbit (orbit) the galactic center.
The sun might have once resided in a different arm. And since it was formed 4 billion years ago, the Sun has traveled around the galaxy 16 times.