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Spiral galaxy

Index Spiral galaxy

Spiral galaxies form a class of galaxy originally described by Edwin Hubble in his 1936 work The Realm of the Nebulae(pp. 124–151) and, as such, form part of the Hubble sequence. [1]

91 relations: Active galactic nucleus, Andromeda Galaxy, Barred spiral galaxy, Bertil Lindblad, Brady Haran, Bulge (astronomy), BX442, Cambridge University Press, Cepheid variable, Chia-Chiao Lin, Cosmic dust, Dark matter, Density wave theory, Disc galaxy, Dwarf elliptical galaxy, Dwarf galaxy, Dwarf spheroidal galaxy, Edwin Hubble, Elliptical galaxy, Flocculent spiral galaxy, Frank Shu, Galactic Center, Galactic coordinate system, Galactic corona, Galactic Disc, Galactic halo, Galactic plane, Galaxy, Galaxy color–magnitude diagram, Galaxy formation and evolution, Galaxy merger, Galaxy morphological classification, Galaxy rotation curve, Globular cluster, Grand design spiral galaxy, Great Debate (astronomy), Groombridge 1830, Harlow Shapley, Heber Doust Curtis, Hubble sequence, Hubble volume, Intermediate spiral galaxy, Interstellar medium, Irregular galaxy, Jeans instability, Kapteyn's Star, Lenticular galaxy, Lick Observatory, List of galaxies, List of nearest galaxies, ..., Metallicity, Milky Way, Molecular cloud, Monthly Notices of the Royal Astronomical Society, Mount Wilson Observatory, Nebula, New Scientist, Newtonian dynamics, OB star, Orbit, Orbital inclination, Pinwheel Galaxy, Proper motion, Protostar, Red dwarf, Retrograde and prograde motion, Ring galaxy, Sagittarius A*, Sagittarius Dwarf Spheroidal Galaxy, Science Daily, Seyfert galaxy, Shock wave, Spheroid, Spitzer Space Telescope, SSPSF model, Star, Starburst galaxy, Stellar halo, Stellar population, Sun, Sunflower Galaxy, Supermassive black hole, The Astrophysical Journal, Timeline of knowledge about galaxies, clusters of galaxies, and large-scale structure, Triangulum Galaxy, Tully–Fisher relation, Unbarred spiral galaxy, Universe, University of Nottingham, Whirlpool Galaxy, Yale University Press. Expand index (41 more) »

Active galactic nucleus

An active galactic nucleus (AGN) is a compact region at the center of a galaxy that has a much higher than normal luminosity over at least some portion—and possibly all—of the electromagnetic spectrum, with characteristics indicating that the excess luminosity is not produced by stars.

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Andromeda Galaxy

The Andromeda Galaxy, also known as Messier 31, M31, or NGC 224, is a spiral galaxy approximately 780 kiloparsecs (2.5 million light-years) from Earth, and the nearest major galaxy to the Milky Way.

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Barred spiral galaxy

A barred spiral galaxy is a spiral galaxy with a central bar-shaped structure composed of stars.

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Bertil Lindblad

Bertil Lindblad (Örebro, 26 November 1895 – Saltsjöbaden, outside Stockholm, 25 June 1965) was a Swedish astronomer.

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Brady Haran

Brady John Haran (born 18 June 1976) is an Australian-born British independent filmmaker and video journalist who is known for his educational videos and documentary films produced for BBC News and his YouTube channels, the most notable being Periodic Videos and Numberphile.

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Bulge (astronomy)

In astronomy, a bulge is a tightly packed group of stars within a larger formation.

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BX442 (Q2343-BX442) is a grand design spiral galaxy of type Sc.

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Cambridge University Press

Cambridge University Press (CUP) is the publishing business of the University of Cambridge.

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Cepheid variable

A Cepheid variable is a type of star that pulsates radially, varying in both diameter and temperature and producing changes in brightness with a well-defined stable period and amplitude.

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Chia-Chiao Lin

Chia-Chiao Lin (Chinese: 林家翹; 7 July 1916 – 13 January 2013) was a Chinese-born American applied mathematician and Institute Professor emeritus at the Massachusetts Institute of Technology.

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Cosmic dust

Cosmic dust, also called extraterrestrial dust or space dust, is dust which exists in outer space, as well as all over planet Earth.

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Dark matter

Dark matter is a theorized form of matter that is thought to account for approximately 80% of the matter in the universe, and about a quarter of its total energy density.

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Density wave theory

Density wave theory or the Lin-Shu density wave theory is a theory proposed by C.C. Lin and Frank Shu in the mid-1960s to explain the spiral arm structure of spiral galaxies.

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Disc galaxy

A disc galaxy is a galaxy characterized by a disc, a flattened circular volume of stars.

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Dwarf elliptical galaxy

Dwarf elliptical galaxies, or dEs, are elliptical galaxies that are smaller than ordinary elliptical galaxies.

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Dwarf galaxy

A dwarf galaxy is a small galaxy composed of about 100 million up to several billion stars, a small number compared to the Milky Way's 200–400 billion stars.

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Dwarf spheroidal galaxy

A dwarf spheroidal galaxy (dSph) is a term in astronomy applied to small, low-luminosity galaxies with very little dust and an older stellar population.

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Edwin Hubble

Edwin Powell Hubble (November 20, 1889 – September 28, 1953) was an American astronomer.

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Elliptical galaxy

An elliptical galaxy is a type of galaxy having an approximately ellipsoidal shape and a smooth, nearly featureless image.

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Flocculent spiral galaxy

A flocculent spiral galaxy is a type of spiral galaxy.

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Frank Shu

Frank H. Shu (born June2, 1943), is an American astrophysicist, astronomer and author.

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Galactic Center

The Galactic Center is the rotational center of the Milky Way.

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Galactic coordinate system

The galactic coordinate system is a celestial coordinate system in spherical coordinates, with the Sun as its center, the primary direction aligned with the approximate center of the Milky Way galaxy, and the fundamental plane parallel to an approximation of the galactic plane but offset to its north.

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Galactic corona

The terms galactic corona and gaseous corona have been used in the first decade of the 21st century to describe a hot, ionised, gaseous component in the Galactic halo of the Milky Way.

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Galactic Disc

The Galactic Disc is a component of disc galaxies, such as spiral galaxies and lenticular galaxies.

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Galactic halo

A galactic halo is an extended, roughly spherical component of a galaxy which extends beyond the main, visible component.

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Galactic plane

The galactic plane is the plane on which the majority of a disk-shaped galaxy's mass lies.

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A galaxy is a gravitationally bound system of stars, stellar remnants, interstellar gas, dust, and dark matter.

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Galaxy color–magnitude diagram

The galaxy color–magnitude diagram shows the relationship between absolute magnitude (a measure of luminosity) and mass of galaxies.

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Galaxy formation and evolution

The study of galaxy formation and evolution is concerned with the processes that formed a heterogeneous universe from a homogeneous beginning, the formation of the first galaxies, the way galaxies change over time, and the processes that have generated the variety of structures observed in nearby galaxies.

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Galaxy merger

Galaxy mergers can occur when two (or more) galaxies collide.

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Galaxy morphological classification

Galaxy morphological classification is a system used by astronomers to divide galaxies into groups based on their visual appearance.

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Galaxy rotation curve

The rotation curve of a disc galaxy (also called a velocity curve) is a plot of the orbital speeds of visible stars or gas in that galaxy versus their radial distance from that galaxy's centre.

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Globular cluster

A globular cluster is a spherical collection of stars that orbits a galactic core as a satellite.

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Grand design spiral galaxy

A grand design spiral galaxy is a type of spiral galaxy with prominent and well-defined spiral arms, as opposed to multi-arm and flocculent spirals which have subtler structural features.

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Great Debate (astronomy)

The Great Debate, also called the Shapley–Curtis Debate, was held on 26 April 1920 at the Smithsonian Museum of Natural History, between the astronomers Harlow Shapley and Heber Curtis.

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Groombridge 1830

Groombridge 1830 (also known as 1830 Groombridge or Argelander's Star) is a star in the constellation Ursa Major.

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Harlow Shapley

Harlow Shapley (November 2, 1885 – October 20, 1972) was a 20th-century American scientist, head of the Harvard College Observatory (1921–1952), and political activist during the latter New Deal and Fair Deal.

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Heber Doust Curtis

Heber Doust Curtis (June 27, 1872 – January 9, 1942) was an American astronomer.

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Hubble sequence

The Hubble sequence is a morphological classification scheme for galaxies invented by Edwin Hubble in 1926.

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Hubble volume

In cosmology, a Hubble volume or Hubble sphere is a spherical region of the observable universe surrounding an observer beyond which objects recede from that observer at a rate greater than the speed of light due to the expansion of the Universe.

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Intermediate spiral galaxy

An intermediate spiral galaxy is a galaxy that is in between the classifications of a barred spiral galaxy and an unbarred spiral galaxy.

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Interstellar medium

In astronomy, the interstellar medium (ISM) is the matter and radiation that exists in the space between the star systems in a galaxy.

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Irregular galaxy

An irregular galaxy is a galaxy that does not have a distinct regular shape, unlike a spiral or an elliptical galaxy.

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Jeans instability

In stellar physics, the Jeans instability causes the collapse of interstellar gas clouds and subsequent star formation.

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Kapteyn's Star

Kapteyn's Star is a class M1 red subdwarf about 12.76 light years from Earth in the southern constellation Pictor; it is the closest halo star to the Solar System.

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Lenticular galaxy

A lenticular galaxy (denoted S0) is a type of galaxy intermediate between an elliptical (denoted E) and a spiral galaxy in galaxy morphological classification schemes.

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Lick Observatory

The Lick Observatory is an astronomical observatory, owned and operated by the University of California.

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List of galaxies

The following is a list of notable galaxies.

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List of nearest galaxies

This is a list of known galaxies within 3.59 megaparsecs (11.7 million light-years) of the Solar System, in ascending order of distance.

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In astronomy, metallicity is used to describe the abundance of elements present in an object that are heavier than hydrogen or helium.

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Milky Way

The Milky Way is the galaxy that contains our Solar System.

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Molecular cloud

A molecular cloud, sometimes called a stellar nursery (if star formation is occurring within), is a type of interstellar cloud, the density and size of which permit the formation of molecules, most commonly molecular hydrogen (H2).

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Monthly Notices of the Royal Astronomical Society

Monthly Notices of the Royal Astronomical Society (MNRAS) is a peer-reviewed scientific journal covering research in astronomy and astrophysics.

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Mount Wilson Observatory

The Mount Wilson Observatory (MWO) is an astronomical observatory in Los Angeles County, California, United States.

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A nebula (Latin for "cloud" or "fog"; pl. nebulae, nebulæ, or nebulas) is an interstellar cloud of dust, hydrogen, helium and other ionized gases.

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New Scientist

New Scientist, first published on 22 November 1956, is a weekly, English-language magazine that covers all aspects of science and technology.

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Newtonian dynamics

In physics, the Newtonian dynamics is understood as the dynamics of a particle or a small body according to Newton's laws of motion.

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OB star

OB stars are hot, massive stars of spectral types O or early-type B that form in loosely organized groups called OB associations.

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In physics, an orbit is the gravitationally curved trajectory of an object, such as the trajectory of a planet around a star or a natural satellite around a planet.

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Orbital inclination

Orbital inclination measures the tilt of an object's orbit around a celestial body.

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Pinwheel Galaxy

The Pinwheel Galaxy (also known as Messier 101, M101 or NGC 5457) is a face-on spiral galaxy distanced 21 million light-years (six megaparsecs) away from Earth in the constellation Ursa Major.

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Proper motion

Proper motion is the astronomical measure of the observed changes in the apparent places of stars or other celestial objects in the sky, as seen from the center of mass of the Solar System, compared to the abstract background of the more distant stars.

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A protostar is a very young star that is still gathering mass from its parent molecular cloud.

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Red dwarf

A red dwarf (or M dwarf) is a small and relatively cool star on the main sequence, of M spectral type.

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Retrograde and prograde motion

Retrograde motion in astronomy is, in general, orbital or rotational motion of an object in the direction opposite the rotation of its primary, that is the central object (right figure).

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Ring galaxy

A ring galaxy is a galaxy with a circle-like appearance.

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Sagittarius A*

Sagittarius A* (pronounced "Sagittarius A-star", standard abbreviation Sgr A*) is a bright and very compact astronomical radio source at the center of the Milky Way, near the border of the constellations Sagittarius and Scorpius.

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Sagittarius Dwarf Spheroidal Galaxy

The Sagittarius Dwarf Spheroidal Galaxy (Sgr dSph), also known as the Sagittarius Dwarf Elliptical Galaxy (Sgr dE or Sag DEG), is an elliptical loop-shaped satellite galaxy of the Milky Way.

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Science Daily

Science Daily is an American website that aggregates press releases and publishes lightly edited press releases (a practice called churnalism) about science, similar to Phys.org and EurekAlert!.

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Seyfert galaxy

Seyfert galaxies are one of the two largest groups of active galaxies, along with quasars.

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Shock wave

In physics, a shock wave (also spelled shockwave), or shock, is a type of propagating disturbance.

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A spheroid, or ellipsoid of revolution, is a quadric surface obtained by rotating an ellipse about one of its principal axes; in other words, an ellipsoid with two equal semi-diameters.

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Spitzer Space Telescope

The Spitzer Space Telescope (SST), formerly the Space Infrared Telescope Facility (SIRTF), is an infrared space telescope launched in 2003 and still operating as of 2018.

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SSPSF model

The SSPSF (stochastic self-propagating star formation) model of star formation was proposed by Mueller & Arnett in 1976, generalized afterward by Gerola & Seiden in 1978 and Gerola, Seiden, & Schulman in 1980.

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A star is type of astronomical object consisting of a luminous spheroid of plasma held together by its own gravity.

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Starburst galaxy

A starburst galaxy is a galaxy undergoing an exceptionally high rate of star formation, as compared to the long-term average rate of star formation in the galaxy or the star formation rate observed in most other galaxies.

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Stellar halo

The stellar halo of a galaxy refers to the component of its galactic halo containing stars.

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Stellar population

During 1944, Walter Baade categorized groups of stars within the Milky Way into bluer stars associated with the spiral arms and the general position of yellow stars near the central galactic bulge or within globular star clusters.

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The Sun is the star at the center of the Solar System.

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Sunflower Galaxy

Messier 63 (also known as M63, NGC 5055, or the Sunflower Galaxy) is a spiral galaxy in the constellation Canes Venatici consisting of a central disc surrounded by many short spiral arm segments, the galaxy form known as flocculent.

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Supermassive black hole

A supermassive black hole (SMBH or SBH) is the largest type of black hole, on the order of hundreds of thousands to billions of solar masses, and is found in the centre of almost all currently known massive galaxies.

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The Astrophysical Journal

The Astrophysical Journal, often abbreviated ApJ (pronounced "ap jay") in references and speech, is a peer-reviewed scientific journal of astrophysics and astronomy, established in 1895 by American astronomers George Ellery Hale and James Edward Keeler.

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Timeline of knowledge about galaxies, clusters of galaxies, and large-scale structure

Timeline of galaxies, clusters of galaxies, and large-scale structure of the universe.

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Triangulum Galaxy

The Triangulum Galaxy is a spiral galaxy approximately 3 million light-years (ly) from Earth in the constellation Triangulum.

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Tully–Fisher relation

lenticular galaxies In astronomy, the Tully–Fisher relation (TFR) is an empirical relationship between the mass or intrinsic luminosity of a spiral galaxy and its angular velocity or emission line width.

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Unbarred spiral galaxy

An unbarred spiral galaxy is a type of spiral galaxy without a central bar, or one that is not a barred spiral galaxy.

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The Universe is all of space and time and their contents, including planets, stars, galaxies, and all other forms of matter and energy.

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University of Nottingham

The University of Nottingham is a public research university in Nottingham, United Kingdom.

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Whirlpool Galaxy

The Whirlpool Galaxy, also known as Messier 51a, M51a, and NGC 5194, is an interacting grand-design spiral galaxy with a Seyfert 2 active galactic nucleus.

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Yale University Press

Yale University Press is a university press associated with Yale University.

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Redirects here:

Galactic Bulge, Galactic spheroid, Galaxy bulge, Galaxy: Spiral, Halo star, Spheroidal halo, Spiral Galaxies, Spiral Galaxy, Spiral arm, Spiral arms, Spiral galaxies, Spiral nebula, Spiral nebulae, Stellar haloes, Stellar halos, Stellar spheroid.


[1] https://en.wikipedia.org/wiki/Spiral_galaxy

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