Image: Hubble captures a cannibal galaxy

This remarkable spiral galaxy, known as NGC 4651, may look serene and peaceful as it swirls in the vast, silent emptiness of space, but don't be fooled—it keeps a violent secret. It is believed that this galaxy consumed ...

Image: Hubble hooks a one-arm galaxy

NGC 4618 was discovered on April 9, 1787, by the German-British astronomer William Herschel, who also discovered Uranus in 1781. Only a year before discovering NGC 4618, Herschel theorized that the "foggy" objects astronomers ...

Image: Hubble gazes at fluffy-looking galaxy

This image taken by the NASA/ESA Hubble Space Telescope shows the galaxy NGC 4237. Located about 60 million light-years from Earth in the constellation of Coma Berenices (Berenice's Hair), NGC 4237 is classified as a flocculent ...

Image: Hubble investigates hungry galaxy

The subject of this image taken by the NASA/ESA Hubble Space Telescope, a spiral galaxy named NGC 1589, was once the scene of a violent bout of cosmic hunger pangs. As astronomers looked on, a poor, hapless star was seemingly ...

Image: Hubble spies galactic traffic jam

The barred spiral galaxy NGC 3887, seen here as viewed by the Wide Field Camera 3 aboard the NASA/ESA Hubble Space Telescope, lies over 60 million light-years away from us in the southern constellation of Crater (the Cup). ...

Image: Hubble fingerprints a galaxy

The NASA/ESA Hubble Space Telescope is no stranger to spiral galaxies. The telescope has brought us some of the most beautiful images ever taken of our spiral neighbors—and the galaxy known as NGC 4689 is no exception.

Image: Hubble embraces spiral with open arms

The spiral galaxy NGC 2008 sits center stage, its ghostly spiral arms spreading out toward us, in this image captured by the NASA/ESA Hubble Space Telescope.

Fast radio burst with steady 16-day cycle observed

A large team of space scientists working in Canada has found evidence of a fast radio burst with a steady 16-day cycle. The team has published a paper describing their findings on the arXiv preprint server.

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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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