Definitions for spiral galaxy
spi·ral gal·axy

Princeton's WordNetRate this definition:5.0 / 1 vote

1. spiral galaxy, spiral nebulanoun

   a galaxy having a spiral structure; arms containing younger stars spiral out from old stars at the center

WiktionaryRate this definition:0.0 / 0 votes

1. spiral galaxynoun

   A galaxy having a number of arms of younger stars that spiral out from the centre containing older ones

WikipediaRate this definition:0.0 / 0 votes

1. Spiral galaxy

   Spiral galaxies form a class of galaxy originally described by Edwin Hubble in his 1936 work The Realm of the Nebulae and, as such, form part of the Hubble sequence. Most spiral galaxies consist of a flat, rotating disk containing stars, gas and dust, and a central concentration of stars known as the bulge. These are often surrounded by a much fainter halo of stars, many of which reside in globular clusters. Spiral galaxies are named by their spiral structures that extend from the center into the galactic disc. The spiral arms are sites of ongoing star formation and are brighter than the surrounding disc because of the young, hot OB stars that inhabit them. Roughly two-thirds of all spirals are observed to have an additional component in the form of a bar-like structure, extending from the central bulge, at the ends of which the spiral arms begin. The proportion of barred spirals relative to barless spirals has likely changed over the history of the universe, with only about 10% containing bars about 8 billion years ago, to roughly a quarter 2.5 billion years ago, until present, where over two-thirds of the galaxies in the visible universe (Hubble volume) have bars.The Milky Way is a barred spiral, although the bar itself is difficult to observe from Earth's current position within the galactic disc. The most convincing evidence for the stars forming a bar in the galactic center comes from several recent surveys, including the Spitzer Space Telescope.Together with irregular galaxies, spiral galaxies make up approximately 60% of galaxies in today's universe. They are mostly found in low-density regions and are rare in the centers of galaxy clusters.

FreebaseRate this definition:0.0 / 0 votes

1. Spiral galaxy

   A spiral galaxy is a certain kind of galaxy originally described by Edwin Hubble in his 1936 work The Realm of the Nebulae and, as such, forms part of the Hubble sequence. Spiral galaxies consist of a flat, rotating disk containing stars, gas and dust, and a central concentration of stars known as the bulge. These are surrounded by a much fainter halo of stars, many of which reside in globular clusters. Spiral galaxies are named for the spiral structures that extend from the center into the disk. The spiral arms are sites of ongoing star formation and are brighter than the surrounding disk because of the young, hot OB stars that inhabit them. Roughly two-thirds of all spirals are observed to have an additional component in the form of a bar-like structure, extending from the central bulge, at the ends of which the spiral arms begin. Our own Milky Way has recently been confirmed to be a barred spiral, although the bar itself is difficult to observe from our position within the Galactic disk. The most convincing evidence for its existence comes from a recent survey, performed by the Spitzer Space Telescope, of stars in the Galactic center. Together with irregular galaxies, spiral galaxies make up approximately 60% of galaxies in the local Universe. They are mostly found in low-density regions and are rare in the centers of galaxy clusters.

Matched Categories

1. • Galaxy

How to pronounce spiral galaxy?

1. Alex

   US English

   David

   US English

   Mark

   US English

   Daniel

   British

   Libby

   British

   Mia

   British

   Karen

   Australian

   Hayley

   Australian

   Natasha

   Australian

   Veena

   Indian

   Priya

   Indian

   Neerja

   Indian

   Zira

   US English

   Oliver

   British

   Wendy

   British

   Fred

   US English

   Tessa

   South African

How to say spiral galaxy in sign language?

Numerology

1. Chaldean Numerology

   The numerical value of spiral galaxy in Chaldean Numerology is: 5

2. Pythagorean Numerology

   The numerical value of spiral galaxy in Pythagorean Numerology is: 1

Examples of spiral galaxy in a Sentence

1. Vanna Bonta:

   Looking up and out, how can we not respect this ever-vigilant cognizance that distinguishes us: the capability to envision, to dream, and to invent? the ability to ponder ourselves? and be aware of our existence on the outer arm of a spiral galaxy in an immeasurable ocean of stars? Cognizance is our crest.