A flocculent spiral galaxy is a type of spiral galaxy. Unlike the well-defined spiral architecture of a grand design spiral galaxy, flocculent (meaning "flaky") galaxies are patchy, with discontinuous spiral arms. [1] [2] Self-propagating star formation is the apparent explanation for the structure of flocculent spirals. [3] Approximately 30% of spirals are flocculent, 10% are grand design, and the rest are referred to as "multi-armed". [4] The multiple-arm type is sometimes grouped into the flocculent category. [5]
Example | Class | Image | Constellation | Notes |
---|---|---|---|---|
NGC 1325 | SBbc | Eridanus | ||
NGC 1353 | SBb | Eridanus | ||
NGC 2775 | SA(r)ab | Cancer | [7] | |
NGC 2841 | SA(r)b | Ursa Major | [6] | |
NGC 3521 | SAB(r s)bc | Leo | [6] | |
NGC 4298 | SA(r s)c | Coma Berenices | ||
NGC 4414 | SA(r s)c | Coma Berenices | [8] | |
NGC 7793 | SA(s)d | Sculptor | [6] | |
Sunflower Galaxy (Messier 63) | SAB(r s)cd | Canes Venatici | [9] | |
An irregular galaxy is a galaxy that does not have a distinct regular shape, unlike a spiral or an elliptical galaxy. Irregular galaxies do not fall into any of the regular classes of the Hubble sequence, and they are often chaotic in appearance, with neither a nuclear bulge nor any trace of spiral arm structure.
Spiral arms are a defining feature of spiral galaxies. They manifest as spiral-shaped regions of enhanced brightness within the galactic disc. Typically, spiral galaxies exhibit two or more spiral arms. The collective configuration of these arms is referred to as the spiral pattern or spiral structure of the galaxy.
The Whirlpool Galaxy, also known as Messier 51a (M51a) or NGC 5194, is an interacting grand-design spiral galaxy with a Seyfert 2 active galactic nucleus. It lies in the constellation Canes Venatici, and was the first galaxy to be classified as a spiral galaxy. It is 7.22 megaparsecs away and 23.58 kiloparsecs (76,900 ly) in diameter.
A barred spiral galaxy is a spiral galaxy with a central bar-shaped structure composed of stars. Bars are found in about two thirds of all spiral galaxies in the local universe, and generally affect both the motions of stars and interstellar gas within spiral galaxies and can affect spiral arms as well. The Milky Way Galaxy, where the Solar System is located, is classified as a barred spiral galaxy.
NGC 4414, also known as the Dusty Spiral Galaxy, is an unbarred spiral galaxy about 62 million light-years away in the constellation Coma Berenices. It was discovered by German-British astronomer William Herschel on 13 March 1785.
NGC 7793 is a flocculent spiral galaxy in the southern constellation of Sculptor. It was discovered in 1826 by Scottish astronomer James Dunlop. The galaxy is located at a distance of 12.2 million light years and is receding with a heliocentric radial velocity of 227 km/s. NGC 7793 is one of the five brightest galaxies within the Sculptor Group.
NGC 2841 is an unbarred spiral galaxy in the northern circumpolar constellation of Ursa Major. It was discovered on 9 March, 1788 by German-born astronomer William Herschel. J. L. E. Dreyer, the author of the New General Catalogue, described it as, "very bright, large, very much extended 151°, very suddenly much brighter middle equal to 10th magnitude star". Initially thought to be about 30 million light-years distant, a 2001 Hubble Space Telescope survey of the galaxy's Cepheid variables determined its distance to be approximately 14.1 megaparsecs or 46 million light-years. The optical size of the galaxy is 8.1′ × 3.5′.
NGC 2997 is a face-on unbarred spiral galaxy about 40 million light-years away in the faint southern constellation of Antlia. It was discovered March 4, 1793 by German-born astronomer William Herschel. J. L. E. Dreyer described it as, "a remarkable object, very faint, very large, very gradually then very suddenly bright middle and 4 arcsec nucleus. This is the brightest galaxy of the NGC 2997 group of galaxies, and was featured on the cover of the first edition of Galactic Dynamics by James Binney and Scott Tremaine.
NGC 4088 is an intermediate spiral galaxy in the constellation Ursa Major. The galaxy forms a physical pair with NGC 4085, which is located 11′ away.
NGC 1042 is a spiral galaxy located in the constellation Cetus. It was discovered on 10 November 1885 by American astronomer Lewis Swift. The galaxy has an apparent magnitude of 14.0.
NGC 5676 is an unbarred spiral galaxy in the constellation Boötes.
NGC 4323 is a lenticular or dwarf elliptical galaxy located about 52.5 million light-years away in the constellation Coma Berenices. The galaxy was discovered in 1882 by astronomer Wilhelm Tempel and is a member of the Virgo Cluster.
NGC 925 is a barred spiral galaxy located about 30 million light-years away in the constellation Triangulum. German-British astronomer William Herschel discovered this galaxy on 13 September 1784.
NGC 3223 is a faint spiral galaxy in the constellation Antlia. It was discovered on February 2, 1835 by the English astronomer John Herschel. The galaxy lies at a distance of approximately 110 million light years away and is receding with a heliocentric radial velocity of 2,896 km/s.
Debra Meloy Elmegreen is an American astronomer. She was the first woman to graduate from Princeton University with a degree in astrophysics, and she was the first female post-doctoral researcher at the Carnegie Observatories.
NGC 7015 is a spiral galaxy located about 203 million light-years away from Earth in the constellation Equuleus. NGC 7015's calculated velocity is 4,881 km/s (3,033 mi/s). NGC 7015 was discovered by French astronomer Édouard Stephan on September 29, 1878.
NGC 4689 is a spiral galaxy located about 54 million light-years away in the constellation of Coma Berenices. NGC 4689 is also classified as a LINER galaxy. NGC 4689 is inclined at an angle of about 36° which means that the galaxy is seen almost face-on to the Earth's line of sight. NGC 4689 was discovered by astronomer William Herschel on April 12, 1784. The galaxy is a member of the Virgo Cluster.
NGC 4294 is a barred spiral galaxy with flocculent spiral arms located about 55 million light-years away in the constellation Virgo. The galaxy was discovered by astronomer William Herschel on March 15, 1784 and is a member of the Virgo Cluster.
NGC 4298 is a flocculent spiral galaxy located about 53 million light-years away in the constellation Coma Berenices. The galaxy was discovered by astronomer William Herschel on April 8, 1784 and is a member of the Virgo Cluster.
NGC 4393 is a spiral galaxy about 46 million light-years away in the constellation Coma Berenices. It was discovered by astronomer William Herschel on April 11, 1785. It is a member of the NGC 4274 Group, which is part of the Coma I Group or Cloud.