Quick Answer: What Is In The Middle Of A Spiral Galaxy?

What are the 3 parts of a spiral galaxy?

Spiral galaxies have three main components: a bulge, disk, and halo (see right).

The bulge is a spherical structure found in the center of the galaxy.

This feature mostly contains older stars.

The disk is made up of dust, gas, and younger stars..

What color is the central part of a spiral galaxy?

redBoth the arms and the disk of a spiral system are blue in color, whereas its central areas are red like an elliptical galaxy.

How do scientists know the Milky Way is a spiral galaxy?

1) When you look toward the galactic center with your eye, you see a long, thin strip. This suggests a disk seen edge-on, rather than a ellipsoid or another shape. We can also detect the bulge at the center. Since we see spiral galaxies which are disks with central bulges, this is a bit of a tipoff.

Do elliptical galaxies have spiral arms?

Elliptical galaxies are ellipsoidal in shape, contain no spiral arms, contain little interstellar gas or dust, and are found mostly in rich clusters of galaxies. Elliptical galaxies appear typically yellow-red, as opposed to spirals which have spiral arms that appear quite blue.

Why does the bulge of a spiral galaxy appear yellowish in Colour?

The central bulge or bar is yellow indicating older stars, while the bright nebulae and young blue stars formed from gas and dust in the galaxy trace out the spiral arms within the disk. … Only about 2% of the mass of Sa spiral galaxies is present in the form of gas and dust.

How does a spiral galaxy form?

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.

Can an elliptical galaxy evolve into a spiral?

There is no way that an elliptical galaxy could spontaneously begin rotating, so there is no way an elliptical galaxy could turn into a spiral galaxy.

What is a difference between a barred spiral galaxy and a normal spiral galaxy?

In barred spirals, the spiral arms of the galaxy appear to spring out of the ends of the bar. As their name suggests, elliptical galaxies are round or oval, with stars distributed fairly uniformly throughout. They have a bulge and halo, like spiral galaxies, but don’t have the flat disk of stars.

What best describes the origin of a spiral galaxy’s spiral arms?

The spiral arms are a wave of star formation caused by wave of density propagating outward through the disk of the galaxy. … They orbit the galactic center with many different inclinations, while disk stars all orbit in nearly the same plane.

What is the average size of a spiral galaxy?

Spiral galaxies come in a wide range of sizes, from 5 to 100 kiloparsecs across, have masses between 109 and 1012 solar masses, and luminosities ranging from 108 to 1011 time that of the Sun. The majority of spiral galaxies rotate in the sense that the arms trail the direction of the spin.

What is an example of a spiral galaxy?

The Milky Way is between the “b” and “c” groups with a bar, so it is an SBbc-type spiral galaxy. Most spirals are luminous. Some other examples of spiral galaxies are M31 (the Andromeda Galaxy) and M33 (a small spiral in the Local Group). … The Andromeda Galaxy (=M 31): a large spiral galaxy (Sb) near the Milky Way.

What are the characteristics of a spiral galaxy?

Most spiral galaxies contain a central bulge surrounded by a flat, rotating disk of stars. The bulge in the center is made up of older, dimmer stars, and is thought to contain a supermassive black hole. Approximately two-thirds of spiral galaxies also contain a bar structure through their center, as does the Milky Way.

How old are stars in a spiral galaxy?

The oldest spiral galaxy on file is BX442. At eleven billion years old, it is more than two billion years older than any previous discovery. Researchers think the galaxy’s shape is caused by the gravitational influence of a companion dwarf galaxy.

How many stars are in a spiral galaxy?

Explanation: Estimate of stars varies from 200 billion to 400 billion. Milky way is a barred spiral.

What causes the spiral arms in galaxies?

Astronomers believe that galaxies have spiral arms because galaxies rotate – or spin around a central axis – and because of something called “density waves.” … Stars pass through the wave as they orbit the galaxy center. The wave causes the stars to slow slightly and temporarily clump together.

Do all galaxies have spiral arms?

“Some galaxies have no long spiral arms at all, but only numerous, short and non-symmetric arms, as in the Sculptor group galaxy NGC 7793. These arms are probably not density waves at all, but are short-lived star-forming regions that are sheared into spiral-like pieces by differential rotation of the galaxy.