NGC 772 (also known as ''Arp 78'' or the Fiddlehead Galaxy) is a large

unbarred spiral galaxy An unbarred spiral galaxyAstronomy Pictures(accessed 18 April 2010) is a type of spiral galaxy without a central bar, or one that is not a barred spiral galaxy. It is designated with an SA in the galaxy morphological classification scheme. A ne ...

approximately 106 million

light-year A light-year, alternatively spelled light year (ly or lyr), is a unit of length used to express astronomical distances and is equal to exactly , which is approximately 9.46 trillion km or 5.88 trillion mi. As defined by the International Astr ...

s away in the

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 first constellati ...

Aries Aries may refer to: *Aries (astrology), an astrological sign *Aries (constellation), a constellation in the zodiac Arts, entertainment and media * ''Aries'' (album), by Luis Miguel, 1993 * ''Aries'' (EP), by Alice Chater, 2020 * "Aries" (song), ...

. It was discovered on 29 November 1785 by

German-British There are many Germans living in the United Kingdom, and many Britons or ''German British'' () have German ancestry, including the British royal family. While those born in Germany constitute one of the UK's largest Foreign-born population of the ...

astronomer

William Herschel Frederick William Herschel ( ; ; 15 November 1738 – 25 August 1822) was a German-British astronomer and composer. He frequently collaborated with his younger sister and fellow astronomer Caroline Herschel. Born in the Electorate of Hanover ...

Characteristics

At around 200,000 light years in diameter, NGC 772 is somewhat larger than the

Milky Way Galaxy The Milky Way or Milky Way Galaxy is the galaxy that includes the 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 in other arms of the galaxy, which are ...

, and is surrounded by several

satellite galaxies A satellite galaxy is a smaller companion galaxy that travels on bound orbits within the gravitational potential of a more massive and Luminosity, luminous host galaxy (also known as the primary galaxy). Satellite galaxies and their constituents ...

– including the dwarf elliptical, NGC 770 – whose

tidal force The tidal force or tide-generating force is the difference in gravitational attraction between different points in a gravitational field, causing bodies to be pulled unevenly and as a result are being stretched towards the attraction. It is the ...

s on the larger galaxy have likely caused the emergence of a single elongated outer

spiral arm 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 i ...

that is much more developed and stronger than the others arms.

Halton Arp Halton Christian "Chip" Arp (March 21, 1927 – December 28, 2013) was an American astronomer. He is remembered for his 1966 book ''Atlas of Peculiar Galaxies'', which catalogued unusual-looking galaxies and presented their images. Arp was als ...

includes NGC 772 in his

Atlas of Peculiar Galaxies The ''Atlas of Peculiar Galaxies'' is a Astronomical catalog, catalog of peculiar galaxies produced by Halton Arp in 1966. A total of 338 galaxies are presented in the atlas, which was originally published in 1966 by the California Institut ...

as Arp 78, where it is described as a "Spiral galaxy with a small high-

surface brightness In astronomy, surface brightness (SB) quantifies the apparent brightness or flux density per unit angular area of a spatially extended object such as a galaxy or nebula, or of the night sky background. An object's surface brightness depends on ...

companion". NGC 772 probably has a H II nucleus, but it may be a transitional object.

Supernovae

Three

supernova A supernova (: supernovae or supernovas) is a powerful and luminous explosion of a star. A supernova occurs during the last stellar evolution, evolutionary stages of a massive star, or when a white dwarf is triggered into runaway nuclear fusion ...

e have been observed in NGC 772: * SN 2003hl ( Type II, mag. 16.5) was discovered by LOTOSS (

Lick Observatory The Lick Observatory is an astronomical observatory owned and operated by the University of California. It is on the summit of Mount Hamilton (California), Mount Hamilton, in the Diablo Range just east of San Jose, California, United States. The ...

and Tenagra Observatory Supernova Searches) on 20 August 2003. * SN 2003iq (Type II, mag. 16.4) was discovered by Jean-Marie Llapasset on 8 October 2003. This supernova was visible at the same time as SN 2003hl, which was discovered 7 weeks prior. * SN 2022qze ( type II-P, mag. 19.89) was discovered by

Pan-STARRS The Panoramic Survey Telescope and Rapid Response System (Pan-STARRS1; List of observatory codes, obs. code: IAU code#F51, F51 and Pan-STARRS2 obs. code: IAU code#F52, F52) located at Haleakala Observatory, Hawaii, US, consists of astronomical ...

on 8 August 2022.

Gallery

File:NGC 772 by Goran Nilsson & The Liverpool Telescope.jpg, RGB image of the galaxy NGC 772 and dwarf galaxy NGC 770 (top center) interacting, from the

Liverpool Telescope The Liverpool Telescope (LT) is a two-metre-aperture robotic Ritchey–Chrétien telescope that observes autonomously (without human intervention). However professional astronomers, school groups and other credible registered users submit specif ...

File:NGC 772 A Rival to the Milky Way.jpg, Center of the galaxy imaged by the

Hubble Space Telescope The Hubble Space Telescope (HST or Hubble) is a space telescope that was launched into low Earth orbit in 1990 and remains in operation. It was not the Orbiting Solar Observatory, first space telescope, but it is one of the largest and most ...

References

External links

Spiral Galaxy NGC 772; Elliptical Galaxy NGC 770
*
NGC 772 (Arp 78) at Constellation Guide
Unbarred spiral galaxies Aries (constellation) 0772 01466 007525 078 Interacting galaxies 17851129 Discoveries by William Herschel 01565+1845 +03-06-011 {{Spiral-galaxy-stub

Characteristics

Supernovae

Gallery

See also

References

External links