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What are spiral arms caused by?
Astronomers believe that galaxies have spiral arms because galaxies rotate – or spin around a central axis – and because of something called “density waves.” Galactic density waves are like water waves. Water itself doesn’t move across a pond – instead, wave energy moves and affects the water as it passes.
What is the spiral arm in astronomy?
The spiral arms of galaxies are the the main production centres of young stars. The more gas and dust available, the greater the fraction of the galaxy that can be involved in star formation. These high-production galaxies tend to be dominated by their spiral arms and have relatively small central bulges.
What do spiral arms in a galaxy represent?
The disk of stars orbiting the bulge separates into arms that circle the galaxy. These spiral arms contain a wealth of gas and dust and younger stars that shine brightly before their quick demise.
Why are spiral arms important?
One explanation centers on the fact that gravitational systems act to increase their central binding energy. Spiral arms remove angular momentum from the center of the galaxy, allowing it to achieve a state of higher binding energy.
What is the leading explanation for the existence of spiral arms?
The leading explanation for the existence of spiral arms are: passages of spiral density waves through the interstellar medium. Most of the mass of the Milky Way seems to exist in the form of: dark matter out in the Halo.
What are the four main parts of a spiral galaxy?
What are the four main parts of a spiral galaxy? A halo, bulge, dish, and arms.
What stars are in spiral arms?
Spiral Galaxies Waves propagating through the disk form the spiral arms that we see, and cause the gas clouds to collapse and form new stars. Because the spiral arms are regions of active star formation they contain many hot young blue and blue-white stars, making them extremely visible.
What do the spiral arms in spiral galaxies contain quizlet?
The arms of spiral galaxies contain most of the bright, blue O and B type stars. Spiral arms are caused by spiral density waves – a spiral shaped disturbances traveling through the disk of the galaxy that compressed gas and triggers star formation.
What are the Milky Way’s spiral arms called?
The Milky Way is known to have two main spiral arms, the Perseus arm and the Scutum-Centaurus arm. Our galaxy also possesses two less pronounced arms, or spurs, called the Sagittarius and the Local Arm (which passes close to the sun).
Where are spiral galaxies found?
Spiral galaxies are mostly found in low-density regions, and very rarely at the center of galaxy clusters. Most spiral galaxies contain a supermassive black hole in the center of the central bulge. Spiral galaxies tend to be the brightest galaxies in the universe.
Which of the following are evidence that spiral arms are sites of star formation?
Which of the following are evidence that spiral arms are sites of star formation? The sun has orbited the galaxy a number of times since it formed. The sun has passed through a number of spiral arms since it formed. The sun left the spiral arm, where it formed, long ago.
What are the 3 main parts of our galaxy?
The three major components of the Milky Way are referred to as the disk, bulge, and the halo.
What do the spiral arms in the sky mean?
The spiral arms are where the stars pile up as they orbit the center. They are like the entrance ramps onto a busy highway during rush hour: when a car comes to the point where many other cars are merging, it slows down and cars jam up. But eventually, the car moves past the ramp and speeds up.
How are the arms of a spiral galaxy measured?
The arms of a spiral galaxy are measured in something called a pitch. If a spiral is so tightly wound that it forms a circle, the pitch angle is zero degrees. As the spiral arm opens up, the number denoting the degree of the pitch angle goes up.
What kind of stars are in the spiral arms?
There are many stars that are also in-between the spiral arms, but they tend to be the dimmer stars (G, K, M-type stars). Long-lived stars will move in and out of the spiral arms as they orbit the galaxy.
What’s the pitch of the spiral arm in the Milky Way?
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 we examined really stands out at an angle of nearly 60 degrees.