Which of the following statements is not true of spiral arms:
they tend to trail the rotation of the galaxy
they are sites of star formation
they are amplified by resonances between the epicyclic frequencies of stars and the angular frequency of the spiral pattern
they arise simply from differential rotation
OK, I'll give you this one, "they tend to trail the rotation of the galaxy." Oops, may be wrong.
maybe? very scientific answer...
To determine which statement is not true of spiral arms, we need to evaluate each statement individually.
1. They tend to trail the rotation of the galaxy: This statement is true. Spiral arms generally trail the rotation of the galaxy, meaning they follow the rotating motion.
2. They are sites of star formation: This statement is also true. Spiral arms are known to be areas of high-density gas and dust, which can trigger the formation of new stars.
3. They are amplified by resonances between the epicyclic frequencies of stars and the angular frequency of the spiral pattern: This statement is true. Spiral arms can be amplified by resonances, resulting from the synchronization of the oscillation frequencies of stars in their orbits with the spiral pattern's rotation.
4. They arise simply from differential rotation: This statement is not true. Spiral arms are not formed solely due to differential rotation, which refers to the difference in angular velocity between different parts of a spinning object. Other factors, such as density waves and gravitational interactions, play essential roles in the formation and maintenance of spiral arms.
Therefore, the statement that is not true of spiral arms is: "They arise simply from differential rotation."