NGC 4725 is an intermediate

barred spiral galaxy 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, and generally affect both the motions of stars and interstellar gas within spiral galaxi ...

with a prominent ring structure, located in the northern

constellation A constellation is an area on the celestial sphere in which a group of visible stars forms Asterism (astronomy), a perceived pattern or outline, typically representing an animal, mythological subject, or inanimate object. The origins of the e ...

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 hemisphere ...

near the

north galactic pole 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 ap ...

. It was discovered by German-born astronomer

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 H ...

on April 6, 1785. The galaxy lies at a distance of approximately from the

Milky Way The Milky Way is the galaxy that includes our Solar System, with the name describing the galaxy's appearance from Earth: a hazy band of light seen in the night sky formed from stars that cannot be individually distinguished by the naked eye ...

. NGC 4725 is the brightest member of the

Coma I Group The Coma I Group is a group of galaxies located about away in the constellation Coma Berenices. The brightest member of the group is NGC 4725. The Coma I Group is rich in spiral galaxies while containing few elliptical and lenticular galaxies. ...

of the Coma-Sculptor Cloud, although it is relatively isolated from the other members of this group. This galaxy is strongly disturbed and is interacting with neighboring spiral galaxy NGC 4747, with its spiral arms showing indications of warping. The pair have an

angular separation Angular distance \theta (also known as angular separation, apparent distance, or apparent separation) is the angle between the two sightlines, or between two point objects as viewed from an observer. Angular distance appears in mathematics (in pa ...

of , which corresponds to a projected linear separation of . A tidal plume extends from NGC 4747 toward NGC 4725. This is a suspected type 2

Seyfert galaxy Seyfert galaxies are one of the two largest groups of active galaxies, along with quasars. They have quasar-like nuclei (very luminous, distant and bright sources of electromagnetic radiation) with very high surface brightnesses whose spectra ...

with a

supermassive black hole A supermassive black hole (SMBH or sometimes SBH) is the largest type of black hole, with its mass being on the order of hundreds of thousands, or millions to billions of times the mass of the Sun (). Black holes are a class of astronomical obj ...

at the core. The morphological classification of this galaxy is SAB(r)ab pec, indicating a peculiar, weakly-barred spiral galaxy (SAB) with a complete ring surrounding the bar (r) and somewhat 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''galactic plane The galactic plane is the plane on which the majority of a disk-shaped galaxy's mass lies. The directions perpendicular to the galactic plane point to the galactic poles. In actual usage, the terms ''galactic plane'' and ''galactic poles'' usuall ...

is inclined by approximately 46° to the line of sight from the Earth. The ring structure of the galaxy is a region of

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

. It is offset from the galactic center and displays non-circular motion. There is a compact radio source positioned approximately from the nucleus of NGC 4725. Since there is no optical counterpart at that position, this may be a star forming region that is heavily obscured by dust. Multiple supernova candidate events have been detected in this galaxy: * SN 1940B was detected on a photograph taken May 5, 1940, about northeast of the galactic core. The

light curve In astronomy, a light curve is a graph of light intensity of a celestial object or region as a function of time, typically with the magnitude of light received on the y axis and with time on the x axis. The light is usually in a particular frequ ...

indicates this was a

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 ...

. * Candidate SN 1987E was detected April 24, 1987 with a magnitude of 15.65. A follow-up study failed to detect this event, so it may have been the result of

gravitational lensing A gravitational lens is a distribution of matter (such as a galaxy cluster, cluster of galaxies) between a distant light source and an observer that is capable of bending the light from the source as the light travels toward the observer. This ...

. * SN 1999gs was detected on December 28, 1999 with a magnitude of 19.3. It was positioned west and south of the nucleus of NGC 4725. * On automated images taken July 5, 2016, a magnitude 17.0 transient source was discovered at an angular separation of from the galactic nucleus. Designated ASASSN-16gu (AT 2016cyu), this was most likely a

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 when ...

event. It had an estimated

absolute visual magnitude Absolute magnitude () is a measure of the luminosity of a celestial object on an inverse logarithmic astronomical magnitude scale. An object's absolute magnitude is defined to be equal to the apparent magnitude that the object would have if it ...

of –13.6.

References

External links

NOAO: NGC 4725

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{{DEFAULTSORT:NGC 4725 Barred spiral galaxies Peculiar galaxies Seyfert galaxies Interacting galaxies Coma I Group Coma Berenices 4725 07989 43451