Citizen astronomers and AI discover 30,000 ring galaxies

Building on the synergy between citizen astronomer classifications and AI, astronomers have discovered approximately 400,000 spiral galaxies and 30,000 ring galaxies in data from the Subaru Telescope. This is the first example ...

Hubble sees spiral galaxy NGC 4423 edge-on

This NASA/ESA Hubble Space Telescope image shows NGC 4423, a galaxy that lies about 55 million light-years away in the constellation Virgo. In this image, NGC 4423 appears to have quite an irregular, tubular form, so it might ...

Image: Spiral galaxy NGC 4254's dazzling swirls

NGC 4254, a spiral galaxy, is resplendent in orange and blue in this Jan. 29, 2024, image from the James Webb Space Telescope. This is one of 19 nearby spiral galaxies recently imaged by the telescope as part of the long-standing ...

Hubble spots a galaxy shrouded by stars

This NASA/ESA Hubble Space Telescope image shows a densely packed field of stars laid upon a background of dust, gas, and light from more distant celestial objects. There are so many stars in this image's field of view that ...

Hubble captures a suspected galaxy encounter

UGC 3912 is classified as a spiral galaxy, but you wouldn't know it from this detailed NASA Hubble Space Telescope image. UGC 3912's distorted shape is typically indicative of a gravitational encounter with another galaxy. ...

Hubble captures interacting galaxies NGC 5410 and UGC 8932

A pair of small, interacting galaxies shine in this new NASA Hubble Space Telescope image. The larger of the two galaxies is named NGC 5410 and was discovered in 1787 by British astronomer William Herschel. It spans 80,000 ...

Hubble views NGC 3384, a galaxy settling into old age

NGC 3384, visible in this image, has many of the characteristic features of so-called elliptical galaxies. Such galaxies glow diffusely, are rounded in shape, display few visible features, and rarely show signs of recent ...

Image: Hubble spies side-by-side galaxies

A barred spiral galaxy and a lenticular galaxy come together to create this interacting pair known as Arp 140. The lenticular galaxy, NGC 274, is visible on the right side of this new NASA Hubble Space Telescope image, and ...

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Spiral galaxy

A spiral galaxy is a galaxy belonging to one of the three main classes 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 (usually two-armed) 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 half 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 been recently (in the 1990s) 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 irregulars, 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.

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