What is the winding dilemma What does it tell us about the nature of the spiral arms?

What is the winding dilemma? What does it tell us about the nature of spiral arms? That the spiral arms of the Milky Way should have disappeared by now because of how tight the spiral should have gotten by now.

What causes the spiral effect of the spiral galaxy?

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.

How does a spiral galaxy rotate?

About half of all spiral galaxies appear to be rotating clockwise and the other half counterclockwise. In most cases, spiral galaxies spin with their arms trailing the direction of rotation.

What happens to spiral galaxies?

As time progresses from 1 to 6, the galaxies’ spiral shapes become stretched out and are ultimately destroyed. Q: Why do two colliding spiral galaxies form an elliptical galaxy rather than one larger spiral galaxy? A: When two spiral galaxies collide, gravity is the main force that comes into play.

What is the winding problem?

The result is that the outer objects lag behind the inner objects causing the spiral to wind up tighter and tighter until ultimately it disappears. This is known as the ‘winding problem’. If we trace them over a few rotations, the spiral arm they define would wind up tightly – and could not persist as observed.

What causes spiral density waves?

The first is that spiral arms are really indications of density waves (slowly moving regions of higher density) in the disk of the galaxy. The second is that the spiral structure is generated by self-sustaining star formation, coupled with the differential rotation of the galaxy.

What is most likely the cause of the spiral pattern in galaxies like the Milky Way?

Astronomers believe that a galaxy’s spiral structure originates as a density wave emanating from the galactic center. The idea is that the entire disk of a galaxy is filled with material. The spiral arms of a galaxy mark where in the galaxy the density wave recently passed, causing new stars to form and burn brightly.

What causes galaxies to rotate?

We know that galaxy rotation is happening because the Milky Way is a flattened disk, in the same way that the Solar System is a flattened disk. The centrifugal force from the rotation flattens out the galactic disk. All stars in the galactic disk follow roughly circular orbits around the center of the galaxy.

How does spiral galaxy look like?

Perhaps the most familiar kind of galaxy are spiral galaxies. They have a distinctive shape with spiral arms in a relatively flat disk and a central “bulge”. The bulge has a large concentration of stars. The arms and bulge are surrounded by a faint halo of stars.

How do spiral density waves move in a galaxy?

A density wave in a spiral galaxy can be visualised as a traffic jam behind a slow-moving truck. The density moves with the truck over time. As the interstellar material moves into the region of high density, it is compressed which in turn triggers star formation.