Messier 100 (also known as NGC 4321) is a grand design

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. It is designated as SAB in the galaxy morphological classification system devised by Gerard de Vaucouleu ...

in the southern part of the mildly

northern Northern may refer to the following: Geography * North, a point in direction * Northern Europe, the northern part or region of Europe * Northern Highland, a region of Wisconsin, United States * Northern Province, Sri Lanka * Northern Range, a r ...

Coma Berenices Coma Berenices is an ancient asterism in the northern sky, which has been defined as one of the 88 modern constellations. It is in the direction of the fourth galactic quadrant, between Leo and Boötes, and it is visible in both hemisphe ...

. It is one of the brightest and largest galaxies in the

Virgo Cluster The Virgo Cluster is a large cluster of galaxies whose center is 53.8 ± 0.3 Mly (16.5 ± 0.1 Mpc) away in the constellation Virgo. Comprising approximately 1,300 (and possibly up to 2,000) member galaxies, the cluster forms the heart of the la ...

and is approximately 55 million

light-year A light-year, alternatively spelled light year, is a large unit of length used to express astronomical distance, astronomical distances and is equivalent to about 9.46 Orders of magnitude (numbers)#1012, trillion kilometers (), or 5.88 ...

s from our galaxy, its diameter being 107,000 light years, and being about 60% as large. It was discovered by

Pierre Méchain Pierre François André Méchain (; 16 August 1744 – 20 September 1804) was a French astronomer and surveyor who, with Charles Messier, was a major contributor to the early study of deep-sky objects and comets. Life Pierre Méchain was born i ...

in 1781 and 29 days later seen again and entered by

Charles Messier Charles Messier (; 26 June 1730 – 12 April 1817) was a French astronomer. He published an astronomical catalogue consisting of 110 nebulae and star clusters, which came to be known as the ''Messier objects''. Messier's purpose ...

in his catalogue "of nebulae and star clusters". . It was one of the first spiral galaxies to be discovered, and was listed as one of fourteen

spiral nebulae Spiral galaxies form a class of galaxy originally described by Edwin Hubble in his 1936 work ''The Realm of the Nebulae''Lord William Parsons of Rosse in 1850. NGC 4323 and NGC 4328 are satellite galaxies of M100; the former is connected with it by a bridge of luminous matter.

Early observations

After the discovery of M100 by Méchain,

made observations of the galaxy depicting it as a nebula without a

star A star is an astronomical object comprising a luminous spheroid of plasma (physics), plasma held together by its gravity. The List of nearest stars and brown dwarfs, nearest star to Earth is the Sun. Many other stars are visible to the naked ...

. He pointed out that it was difficult to recognize the

nebula A nebula ('cloud' or 'fog' in Latin; pl. nebulae, nebulæ or nebulas) is a distinct luminescent part of interstellar medium, which can consist of ionized, neutral or molecular hydrogen and also cosmic dust. Nebulae are often star-forming regio ...

because of its faintness.

William Herschel Frederick William Herschel (; german: Friedrich Wilhelm Herschel; 15 November 1738 – 25 August 1822) was a German-born British astronomer and composer. He frequently collaborated with his younger sister and fellow astronomer Caroline ...

was able to identify a bright cluster of stars within the "nebula" during his observations. His son

John John is a common English name and surname: * John (given name) * John (surname) John may also refer to: New Testament Works * Gospel of John, a title often shortened to John * First Epistle of John, often shortened to 1 John * Secon ...

expanded the findings in 1833. With the advent of better telescopes, John Herschel was able to see a round, brighter galaxy; however, he also mentioned that it was barely visible through clouds.

William Henry Smyth Admiral William Henry Smyth (21 January 1788 – 8 September 1865) was a Royal Navy officer, hydrographer, astronomer and numismatist. He is noted for his involvement in the early history of a number of learned societies, for his hydrographic ...

extended the studies of M100, detailing it as a pearly white nebula and pointing out diffuse spots.

Star formation

Messier 100 is considered a

starburst galaxy A starburst galaxy is one 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. For example, the star formatio ...

with the strongest

star formation Star formation is the process by which dense regions within molecular clouds in The "medium" is present further soon.-->interstellar space

activity concentrated in its center, within a ring – actually two tightly wound

spiral arm Spiral galaxies form a class of galaxy originally described by Edwin Hubble in his 1936 work ''The Realm of the Nebulae''nuclear bar of radius: one thousand

parsec The parsec (symbol: pc) is a unit of length used to measure the large distances to astronomical objects outside the Solar System, approximately equal to or (au), i.e. . The parsec unit is obtained by the use of parallax and trigonometry, an ...

s – where

star formation Star formation is the process by which dense regions within molecular clouds in The "medium" is present further soon.-->interstellar space

has been taking place for at least 500 million years in separate bursts. As usual on spiral galaxies of the Virgo Cluster, in the rest of the disk both star formation and

neutral hydrogen The hydrogen line, 21 centimeter line, or H I line is the electromagnetic radiation spectral line that is created by a change in the energy state of neutral hydrogen atoms. This electromagnetic radiation has a precise frequency of , w ...

, of which M100 is deficient compared to isolated spiral galaxies of similar Hubble type, are truncated within the galaxy's disk, which is caused by interactions with the

intracluster medium In astronomy, the intracluster medium (ICM) is the superheated plasma that permeates a galaxy cluster. The gas consists mainly of ionized hydrogen and helium and accounts for most of the baryonic material in galaxy clusters. The ICM is heated to t ...

of Virgo.

Supernovae

Seven

supernova A supernova is a powerful and luminous explosion of a star. It has the plural form supernovae or supernovas, and is abbreviated SN or SNe. This transient astronomical event occurs during the last evolutionary stages of a massive star or whe ...

e have been identified in M100. * In March 1901 the first was found, SN 1901B, a type I supernova found with a magnitude of 15.6 at 110"W and 4"N from its nucleus. * SN 1914A was then discovered in February to March 1914; its type was undeterminable but was found with a magnitude of 15.7 at 24"E and 111"S from its nucleus. * Galactic observation from early to mid 1960 found SN 1959E, another type I supernova, with the faintest magnitude, 17.5, among the five found, at 58"E and 21"S from its nucleus. * On April 15, 1979, the first

type II supernova A Type II supernova (plural: ''supernovae'' or ''supernovas'') results from the rapid collapse and violent explosion of a massive star. A star must have at least 8 times, but no more than 40 to 50 times, the mass of the Sun () to undergo this ...

found in the M100 galaxy was discovered; however the star

SN 1979C SN 1979C was a supernova about 50 million light-years away in Messier 100, a spiral galaxy in the constellation Coma Berenices. The Type II supernova was discovered April 19, 1979 by Gus Johnson, a school teacher and amateur astronomer. This type ...

faded quickly; later observations from x-ray to radio wavelengths revealed its remnant. * The fifth supernova was discovered February 7, 2006; the star

SN 2006X SN 2006X was a Type Ia supernova about 65 million light-years away in Messier 100, a spiral galaxy in the constellation Coma Berenices. The supernova was independently discovered in early February 2006 by Shoji Suzuki was a Japanese jazz ...

had a magnitude of 15.3 when discovered two weeks before fading to magnitude +17. * Supernova SN 2019ehk, discovered on April 29, 2019, reached a peak magnitude of approximately 15.8. * The seventh supernova, SN 2020oi, was discovered on January 7, 2020. It was type Ic supernova, which reached a peak magnitude of 17.7.

Gallery

M100.jpg, Image of Messier 100 taken by the NASA/ESA Hubble Space Telescope Noirlab2019b.jpg, Messier 100 Hubble images centered on supernova SN 2019ehk

References and footnotes

External links

SEDS: Spiral Galaxy 100
*
ESA/Hubble Messier 100

{{DEFAULTSORT:Messier 100 Intermediate spiral galaxies Coma Berenices

100 100 or one hundred ( Roman numeral: C) is the natural number following 99 and preceding 101. In medieval contexts, it may be described as the short hundred or five score in order to differentiate the English and Germanic use of "hundred" to de ...