Advertisement

Advertisement

View synonyms for spiral galaxy

spiral galaxy

noun

, Astronomy.
  1. a galaxy having a spiral structure.


spiral galaxy

noun

  1. a galaxy consisting of an ellipsoidal nucleus of old stars from opposite sides of which arms, containing younger stars, spiral outwards around the nucleus. In a barred spiral the arms originate at the ends of a bar-shaped nucleus


spiral galaxy

/ spīrəl /

  1. A galaxy consisting of a rotating flattened disk with an ellipsoidal central bulge from which extend a pattern of two or more luminous spiral arms. Spiral galaxies range from large bulges with tightly wound arms (classified as Sa) to small bulges with loosely wound arms (classified as Sc and in some cases Sd). The majority of the mass of a spiral galaxy is contained in its bulge, made up mostly of old stars, while the arms are composed mostly of younger stars and large amounts of interstellar gas and dust. A spherical, relatively dust-free region known as a galactic halo surrounding a spiral galaxy may contain large amounts of dark matter. The Milky Way is a spiral galaxy.
  2. ◆ A spiral galaxy whose central bulge has the shape of a bar from whose ends the spiral arms emanate is called a barred spiral galaxy . About a third of spiral galaxies have this straight or lozenge-shaped bar of stars, gas, and dust extending out from the nucleus. Barred spiral galaxies are classified similarly to regular spirals, from SBa (large bulge, tightly wound arms) to SBc (smaller bulge, looser arms). Astronomers believe that some elliptical galaxies containing hints of a bar and spiral might once have been barred spiral galaxies.
  3. See illustration at galaxyCompare elliptical galaxySee more at Hubble classification system


Discover More

Word History and Origins

Origin of spiral galaxy1

First recorded in 1910–15

Discover More

Example Sentences

This is because radio telescopes have always struggled to see the much fainter radio emission from normal spiral galaxies like our own Milky Way.

EMU sees almost all the spiral galaxies in the nearby universe that were previously seen only by optical and infrared telescopes.

Another new Hubble image shows a large spiral galaxy that lies 490 million lightyears away.

Many spiral galaxies, including the Milky Way, contain a central bar-shaped region densely packed with stars and surrounded by the galaxy’s pinwheeling arms.

Different parts of spiral galaxies tend to host different types of stars.

Case in point: the spiral galaxy NGC 5548, which astronomers have been monitoring off and on for decades.

Advertisement

Word of the Day

petrichor

[pet-ri-kawr]

Meaning and examples

Start each day with the Word of the Day in your inbox!

By clicking "Sign Up", you are accepting Dictionary.com Terms & Conditions and Privacy Policies.

Advertisement

Advertisement

Advertisement


spiral casingspiral gear