NASA has spotted a contingent of some young stars and star-forming clouds jutting out from the Milky Way’s Sagittarius Arm.
It stretches for some 3,000 light-years and is the first major structure identified with an orientation so dramatically different than the arm.
So far, our understanding of the galaxy’s shape was based upon indirect measurements of celestial landmarks within the Milky Way. Additionally, there were some inferences also from the structures observed in other galaxies populating the universe.
The Milky Way began to form relatively soon after the Big Bang explosion. It is the Big Bang that marks the beginning of the universe.
Astronomers already have a rough idea of the size and shape of the Milky Way’s arms. But they cannot see the full structure of our home galaxy because the earth is inside it.
Young stars and nebulae apparently align closely with the shape of the arms they reside in. And to get a three-dimensional view of the arm segment, the astronomers used the latest data release from the European Space Agency Gaia mission to measure the precise distances to the stars.
Milky Way and Stars
Moreover, the combined data reveals that the long, thin structure associated with the Sagittarius Arm is made of young stars moving at nearly the same velocity and in the same direction through space.
Most models of the Milky Way suggest that the Sagittarius Arm forms a spiral that has a pitch angle of about 12 degrees, But the structure that scientists now examined stands out at an angle of nearly 60 degrees.
Similar structures which are called spurs or feathers are commonly found jutting off the arms of other spiral galaxies.
For decades scientists have been wondering whether our Milky Way’s spiral arms are also dotted with these structures or if they are relatively smooth.
The Milky Way which is spiral-shaped with a central bar-like structure is composed of stars and includes 100 to 400 billion stars, including the sun.
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