NGC 772 (also known as ''Arp 78'') is an

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. Ba ...

approximately 130 million light-years away in the constellation

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

Characteristics

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

Milky Way Galaxy 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. ...

, 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 luminous host galaxy (also known as the primary galaxy). Satellite galaxies and their constituents are bound ...

– including the dwarf

elliptical Elliptical may mean: * having the shape of an ellipse, or more broadly, any oval shape ** in botany, having an elliptic leaf shape ** of aircraft wings, having an elliptical planform * characterised by ellipsis (the omission of words), or by conc ...

NGC 770 NGC 770 is an elliptical galaxy in the constellation Aries. It is around 120 million light years from the Milky Way and has a diameter of around . NGC 770 is gravitationally linked to NGC 772. The galaxy was discovered on November 3, 1855 by R ...

– whose

tidal force The tidal force is a gravitational effect that stretches a body along the line towards the center of mass of another body due to a gradient (difference in strength) in gravitational field from the other body; it is responsible for diverse phenomen ...

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

spiral arm Spiral galaxies form a class of galaxy originally described by Edwin Hubble in his 1936 work ''The Realm of the Nebulae''Halton Arp Halton Christian "Chip" Arp (March 21, 1927 – December 28, 2013) was an American astronomer. He was known for his 1966 ''Atlas of Peculiar Galaxies'', which (it was later theorized) catalogues many examples of interacting and merging galaxie ...

includes NGC 772 in his

Atlas of Peculiar Galaxies The ''Atlas of Peculiar Galaxies'' is a 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 Institute of Technology. The ...

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 it ...

companion". Three supernovae have been observed in NGC 772. SN 2003hl ( Type II, mag. 16.5) was discovered on 20 August 2003. SN 2003iq (Type II, mag. 16.4) was discovered on 8 October 2003. SN 2022qze (type IIP, mag. 19.9) was discovered on 8 August 2022. NGC 772 probably has a H II nucleus, but it may be a transitional object.

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

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

. File:NGC772 SN2003hl SN2003iq 6223 Dahl.jpg, Two supernovae in the galaxy (SN 2003hl & 2003iq) and asteroid 6223 Dahl passing through the shot File:Galaxy NGC 772.jpg, Strong-Arming a Galaxy

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 07525 078 Interacting galaxies {{Spiral-galaxy-stub

Characteristics

Gallery

See also

References

External links