How spiral galaxies are formed?

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 are the spiral arms of a galaxy?

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 are spiral arms Why do stars form there?

The spiral arms in spiral galaxies are one type of environment where gravity is pushing gas and dust to form stars more efficiently than in other parts of a spiral galaxy. This is why you see more star forming regions and collections of young stars (open clusters) in spiral arms than in other parts of a spiral galaxy.

Why are the spiral arms in the galaxy in the figure blue?

Sc and SBc galaxies, for instance, have very “loose” arms, whereas Sa and SBa galaxies have tightly wrapped arms (with reference to the Hubble sequence). Either way, spiral arms contain many young, blue stars (due to the high mass density and the high rate of star formation), which make the arms so bright.

Why are spiral galaxies spiral?

Astronomers believe that galaxies have spiral arms because galaxies rotate – or spin around a central axis – and because of something called “density waves.” A spiral galaxy’s rotation, or spin, bends the waves into spirals. Stars pass through the wave as they orbit the galaxy center.

Why do spiral galaxies rotate?

Their rapid spin is a result of sitting within an extraordinarily massive cloud, or halo, of dark matter – invisible matter detectable only through its gravity. The largest “super spiral” studied here resides in a dark matter halo weighing at least 40 trillion times the mass of our Sun.

Why are there more spiral galaxies in the field?

Astronomers have identified more spiral galaxies than ellipticals, but that’s simply because the spirals are easier to spot. While spiral galaxies are bright, elliptical galaxies are dim.

What is a spiral arm in astronomy?

Spiral arms are regions of stars that extend from the center of spiral and barred spiral galaxies. These long, thin regions resemble a spiral and thus give spiral galaxies their name.

Why are the spiral arms in the galaxy in this image blue What color would the halo be if the halo were bright enough to be seen in this photo?

The spiral arms are blue because there are many hot young massive stars. The halo would be red.

Why are the spiral galaxies bluer than the elliptical galaxies?

So the answer to your question is: The reason spiral galaxies are not red is that they keep forming new stars, the most luminous of which are blue. And the reason elliptical galaxies are not blue is that they’re unable to form new stars, so only the red ones are left.