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. The spiral arms of a grand design galaxy extend clearly around the galaxy through many radians and can be observed over a large fraction of the galaxy's radius. As of 2002, approximately 10 percent of all currently known spiral galaxies are classified as grand design type spirals,[1] including M81, M51, M74, M100, and M101.

A Spitzer Space Telescope image of Messier 81, a grand design spiral.

Origin of structure

Density wave theory is the preferred explanation for the well-defined structure of grand design spirals.[2] According to this theory, the spiral arms are created inside density waves that turn around the galaxy at different speeds from the stars in the galaxy's disk. Stars and gas are clumped in these dense regions due to gravitational attraction towards the dense material, though their location in the spiral arm may not be permanent. When they come close to the spiral arm, they are pulled toward the dense material by the force of gravity; and as they travel through the arm, they are slowed from exiting by the same gravitational pull. This causes the gas in particular to clump in the dense regions, which encourages gas clouds to collapse, producing star formation.


  1. ^ Mihos, Chris (2002-01-11), Spiral Structure, retrieved 2007-05-30
  2. ^ Masters, Karen (September 2002), What is the Origin of Spiral Structure in Galaxies, archived from the original on 2007-06-09, retrieved 2007-05-30

BX442 (Q2343-BX442) is a grand design spiral galaxy of type Sc. It has a companion dwarf galaxy. It is the most distant known grand design spiral galaxy in the universe, with a redshift of z=2.1765 ± 0.0001.

Although commonly referred to as the oldest known grand design spiral galaxy in the universe,

it is more accurately the earliest such galaxy known to exist in the universe, with a lookback time (the difference between the age of the universe now and the age of the universe at the time light left the galaxy) of 10.7 billion years in the concordance cosmology. This time estimate means that structure seen in BX442 developed roughly 3 billion years after the Big Bang, 10 kiloparsecs (30,000 ly) in diameter, and has a mass of 6 × 1010 solar masses.

Flocculent spiral galaxy

A flocculent spiral galaxy is a type of spiral galaxy. Unlike the well-defined spiral architecture of a grand design spiral galaxy, flocculent (meaning "fluffy") galaxies are patchy, with discontinuous spiral arms. Self-propagating star formation is the apparent explanation for the structure of flocculent spirals. Approximately 30% of spirals are flocculent, 10% are grand design, and the rest are referred to as "multi-armed". The multiple-arm type is sometimes grouped into the flocculent category.The prototypical flocculent spiral is NGC 2841.


M100 or M-100 may refer to:

M-100 (Michigan highway), a north–south state trunkline highway in the U.S. state of Michigan

M-100 (rocket), a two-stage Soviet sounding rocket

M100, the magnetoencephalographic equivalent to the N100 large, negative-going evoked potential measured by electroencephalography

Messier 100, a grand design spiral galaxy

Miles Student (M.100), a lightweight trainer aircraft

Palm m100 series, a popular lower cost version of the Palm Pilot

M100 (New York City bus), a New York City Bus route in Manhattan

Effa M100, the Brazilian name for the Changhe Ideal automobile

M100, the second version of the Jeep trailer

M100 Elan, a model of the Lotus Elan automobile

Mercedes-Benz M100 engine, a 6.3/6.9 liter SOHC V8 automobile engine

TRS-80 Model 100, an early portable computerIn athletics:

Masters athletics, an age group for athletes aged 35+

Messier 74

Messier 74 (also known as NGC 628 and Phantom Galaxy) is a spiral galaxy in the constellation Pisces. It is at a distance of about 32 million light-years away from Earth. The galaxy contains two clearly defined spiral arms and is therefore used as an archetypal example of a grand design spiral galaxy. The galaxy's low surface brightness makes it the most difficult Messier object for amateur astronomers to observe. However, the relatively large angular size of the galaxy and the galaxy's face-on orientation make it an ideal object for professional astronomers who want to study spiral arm structure and spiral density waves. It is estimated that M74 is home to about 100 billion stars.

Messier 83

Messier 83 or M83, also known as the Southern Pinwheel Galaxy and NGC 5236, is a barred spiral galaxy approximately 15 million light-years away in the constellation Hydra. Nicolas Louis de Lacaille discovered M83 on February 23, 1752 at the Cape of Good Hope. Charles Messier added it to his catalogue of nebulous objects (now known as the Messier Catalogue) in March 1781. This is one of the closest and brightest barred spiral galaxies in the sky, making it visible with binoculars. Its nickname of the Southern Pinwheel derives from its resemblance to the Pinwheel Galaxy (M101).

This is a massive, grand design spiral galaxy.

The morphological classification of NGC 5236 in the De Vaucouleurs system is SAB(s)c, where the 'SAB' denotes a weak-barred spiral, '(s)' indicates a pure spiral structure with no ring, and 'c' means the spiral arms are loosely wound. The peculiar dwarf galaxy NGC 5253 lies near M83, and the two likely interacted within the last billion years resulting in starburst activity in their central regions.The star formation rate in M83 is higher along the leading edge of the spiral arms, as predicted by density wave theory. NASA's Galaxy Evolution Explorer project reported finding large numbers of new stars in the outer reaches of the galaxy – 20 kpc from the center. It had hitherto been thought that these areas lacked the materials necessary for star formation. Six supernovae have been observed in M83: SN 1923A, SN 1945B, SN 1950B, SN 1957D, SN 1968L and SN 1983N.

M83 is at the center of one of two subgroups within the Centaurus A/M83 Group, a nearby galaxy group. Centaurus A is at the center of the other subgroup. These are sometimes identified as one group and sometimes as two. However, the galaxies around Centaurus A and the galaxies around M83 are physically close to each other, and both subgroups appear not to be moving relative to each other.

Messier 99

Messier 99 or M99, also known as NGC 4254, is a grand design spiral galaxy in the northern constellation Coma Berenices approximately 15 megaparsecs (49 megalight-years) in distance from the Milky Way. It was discovered by Pierre Méchain on March 17, 1781. The discovery was then reported to Charles Messier, who included the object in the Messier Catalogue of comet-like objects. Messier 99 was one of the first galaxies in which a spiral pattern was seen. This pattern was first identified by Lord Rosse in the spring of 1846.This galaxy has a morphological classification of SA(s)c, indicating a pure spiral shape with loosely wound arms. It has a peculiar shape with one normal looking arm and an extended arm that is less tightly wound. The galaxy is inclined by 42° to the line-of-sight with a major axis position angle of 68°. Four supernovae have been observed in this galaxy: SN 1967H (type II), 1972Q, 1986I (type II), and 2014L (type Ic).A bridge of neutral hydrogen gas links NGC 4254 with VIRGOHI21, an HI region and a possible dark galaxy. The gravity from the latter may have distorted M99 and drawn out the gas bridge, as the two galaxy-sized objects may have had a close encounter before they went their separate ways. However, VIRGOHI21 may instead be tidal debris from an interaction with the lenticular galaxy NGC 4262 some 280 million years ago. It is expected that the drawn out arm will relax to match the normal arm once the encounter is over.

While not classified as a starburst galaxy, M99 has a star formation activity three times larger than other galaxies of similar Hubble type that may have been triggered by the encounter. M99 is likely entering the Virgo Cluster for the first time and is located at the periphery of the cluster at a projected separation of 3.7°, or around one megaparsec, from the cluster center at Messier 87. The galaxy is undergoing ram-pressure stripping as it moves through the intracluster medium.

NGC 2608

NGC 2608 (also known as Arp 12) is a barred spiral galaxy located 93 million light-years away in the constellation Cancer (the Crab). It is 62,000 light-years across, and about 60% of the width of the Milky Way. It is considered a grand design spiral galaxy and is classified as SB(s)b, meaning that the galaxy's arms wind moderately (neither tightly nor loosely) around the prominent central bar.

It was classified by Halton Arp (1927-) under "galaxies with split arms" in his 1966 Atlas of Peculiar Galaxies who noted that the "nucleus may be double or superposed star."

NGC 2608 is now considered to be a pair of interacting galaxies.

NGC 2997

NGC 2997 is a face-on unbarred spiral galaxy about 25 million light-years away in the constellation Antlia. It is the brightest galaxy of the NGC 2997 group of galaxies.

NGC 2997 is particularly notable for a nucleus surrounded by a chain of hot giant clouds of ionized hydrogen. It is featured on the cover of the first edition of Galactic Dynamics by James Binney and Scott Tremaine.

NGC 3310

NGC 3310 is a grand design spiral galaxy in the constellation Ursa Major. It is a starburst galaxy and it is likely that NGC 3310 collided with one of its satellite galaxies about 100 million years ago, triggering widespread star formation. It is thought to be located approximately 46 million light-years away from the Earth, and is thought to be about 22,000 light-years wide.

The ring clusters of NGC 3310 have been undergoing starburst activity for at least the last 40 million years.

NGC 3631

NGC 3631 is a spiral galaxy located in the constellation Ursa Major. It is located at a distance of circa 35 million light years from Earth, which, given its apparent dimensions, means that NGC 3631 is about 60,000 light years across. It was discovered by William Herschel οn

April 14, 1789. It is a grand design spiral galaxy seen face on.

NGC 4030

NGC 4030 is a grand design spiral galaxy located about 64 million light years away in the constellation Virgo. With an apparent visual magnitude of 10.6, it is visible with a small telescope as a 3 arc minute wide feature about 4.75° to the southeast of the star Beta Virginis. It is inclined by an angle of 47.1° to the line of sight from the Earth and is receding at a velocity of 1,465 km/s.The morphological classification of NGC 4030 in the De Vaucouleurs system is SA(s)bc, which indicates a spiral structure (SA) with no bar (s) and moderate to loosely wound arms (bc). The inner part of the galaxy shows a complex structure with multiple spiral arms, which becomes a symmetric, double arm pattern beyond 49″ from the core. The central bulge is relatively young with an estimated age of two billion years, while the nucleus is inactive.In 2007, a supernova explosion was discovered in the galaxy from images taken on February 19 from the 1 m Swope telescope at Las Campanas Observatory in Chile. Designated SN 2007aa, it was a type IIP supernova positioned 68″.5 north and 60″.8 east of the galactic nucleus. The progenitor was a red giant star with 8.5–16.5 times the mass of the Sun.

NGC 4088

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 4088 is a grand design spiral galaxy. This means that the spiral arms in the galaxy's disk are sharply defined. In visible light, one of the spiral arms appears to have a disconnected segment. Halton Arp included this galaxy in the Atlas of Peculiar Galaxies as one of several examples where this phenomenon occurs.NGC 4088 and NGC 4085 are members of the M109 Group, a group of galaxies located in the constellation Ursa Major. This large group contains between 41 and 58 galaxies, including the spiral galaxy M109.

NGC 4939

NGC 4939 is a spiral galaxy located in the constellation Virgo. It is located at a distance of circa 120 million light years from Earth, which, given its apparent dimensions, means that NGC 4939 is about 190,000 light years across. It was discovered by William Herschel οn March 25, 1786.

NGC 5247

NGC 5247 is a face-on unbarred spiral galaxy located some 60 million light years away in the constellation Virgo. It most likely belongs to the Virgo Supercluster of galaxies; the same supercluster that hosts the Milky Way galaxy. This is a grand design spiral galaxy that displays no indications of distortion caused by interaction with other galaxies. It has two spiral arms that bifurcate after wrapping halfway around the nucleus. The disk is estimated to be 4.9 ± 2.0 kly (1.5 ± 0.6 kpc) in thickness and it is inclined by roughly 28° to the line of sight.

NGC 5364

NGC 5364 is a grand design spiral galaxy located 54.5 million light years away in the constellation Virgo. It is inclined to the line of sight from the Earth at an angle of 47° along a position angle of 25°.

NGC 5474

NGC 5474 is a peculiar dwarf galaxy in the constellation Ursa Major. It is one of several companion galaxies of the Pinwheel Galaxy (M101), a grand-design spiral galaxy.

Among the Pinwheel Galaxy's companions, this galaxy is the closest to the Pinwheel Galaxy itself. The gravitational interaction between NGC 5474 and the Pinwheel Galaxy has strongly distorted the former. As a result, the disk is offset relative to the nucleus. The star formation in this galaxy (as traced by hydrogen spectral line emission) is also offset from the nucleus. NGC 5474 shows some signs of a spiral structure. As a result, this galaxy is often classified as a dwarf spiral galaxy, a relatively rare group of dwarf galaxies.

NGC 6118

NGC 6118 is a grand design spiral galaxy located 83 million light-years away in the constellation Serpens (the Snake). It measures roughly 110,000 light-years across; about the same as our own galaxy, the Milky Way. Its shape is classified as "SA(s)cd," meaning that it is unbarred and has several rather loosely wound spiral arms. The large numbers of bright bluish knots are active star-forming regions where some very luminous and young stars can be perceived.Because NGC 6118 has loosely wound spiral open arms, no clear defined spiral arms like the Milky Way galaxy and lacks a central bar, the galaxy thus does not have a galactic habitable zone like the Milky Way. For the Milky Way, the galactic habitable zone is commonly believed to be an annulus with an outer radius of about 10 kiloparsecs and an inner radius close to the Galactic Center, both of which lack hard boundaries.NGC 6118 is difficult to see with a small telescope. Amateur astronomers have nicknamed it the "Blinking Galaxy", as it has a tendency to flick in and out of view with different eye positions.

NGC 7096

NGC 7096 is a grand-design spiral galaxy located about 130 million light-years away in the constellation of Indus. NGC 7096 is also part of a group of galaxies that contains the galaxy NGC 7083. NGC 7096 was discovered by astronomer John Herschel on August 31, 1836.

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. It lies in the constellation Canes Venatici, and was the first galaxy to be classified as a spiral galaxy. Its distance is estimated to be between 15 and 35 million light-years.The galaxy and its companion, NGC 5195, are easily observed by amateur astronomers, and the two galaxies may be seen with binoculars. The Whirlpool Galaxy has been extensively observed by professional astronomers, who study it to understand galaxy structure (particularly structure associated with the spiral arms) and galaxy interactions.

Active nuclei
Energetic galaxies
Low activity
See also

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