Hubble views broad and sweeping spiral galaxy NGC 4731

This new image from the NASA/ESA Hubble Space Telescope shows the broad and sweeping spiral galaxy NGC 4731. It lies in the constellation Virgo and is located 43 million light-years from Earth. This highly detailed image ...

Euclid space telescope unveils new images of the cosmos

A mind-boggling number of shining galaxies, a purple and orange star nursery and a spiral galaxy similar to our Milky Way: new images were revealed from Europe's Euclid space telescope on Thursday.

NASA images help explain eating habits of massive black hole

In images from NASA's retired Spitzer Space Telescope, streams of dust thousands of light-years long flow toward the supermassive black hole at the heart of the Andromeda galaxy. It turns out these streams can help explain ...

Hubble spots magnificent barred galaxy NGC 2217

The magnificent central bar of NGC 2217 (also known as AM 0619-271) shines bright in the constellation of Canis Major (The Greater Dog), in this image taken by the NASA/ESA Hubble Space Telescope. Roughly 65 million light-years ...

Hubble captures a bright galactic and stellar duo

This image from the NASA/ESA Hubble Space Telescope features NGC 3783, a bright barred spiral galaxy about 130 million light-years from Earth that also lends its name to the eponymous NGC 3783 galaxy group.

page 1 from 40

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.

This text uses material from Wikipedia, licensed under CC BY-SA