NGC 4242 is a spiral galaxy in the northern constellation of

Canes Venatici Canes Venatici () is one of the 88 constellations designated by the International Astronomical Union (IAU). It is a small northern constellation that was created by Johannes Hevelius in the 17th century. Its name is Latin for 'hunting dogs', and ...

. The galaxy is about 18 million light years (5.5

megaparsec 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, and ...

s) away. It was discovered on 10 April 1788 by

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 ...

, and it was described as "very faint, considerably large, irregular, round, very gradually brighter in the middle, resolvable" by

John Louis Emil Dreyer John Louis Emil Dreyer (13 February 1852 – 14 September 1926) was a Danish astronomer who spent most of his career working in Ireland. He spent the last decade of his life in Oxford, England. Life Dreyer was born in Copenhagen. His fath ...

, the compiler of the New General Catalogue. NGC 4242's galaxy morphological type is SABdm. This means that it is an

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 ...

, with loosely wound spiral arms and is generally irregular in appearance. It was photographed 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 ...

in 2017. The image shows an asymmetric center and a small galactic bar. NGC 4242 has a relatively low

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 ...

and rate of star formation. NGC 4242 may be a

satellite galaxy 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 ...

of Messier 106 and is a member of the

Canes II Group The Canes II Group or Canes Venatici II Group (CVn II Group) is a group of galaxies about 26.1 million light-years away from Earth. The group resides in the Local Supercluster. G. De Vaucouleurs, 1975. ''Nearby Groups of Galaxies'', ch. 5. the ne ...

. SN 2002bu was detected in NGC 4242, brightening to its peak magnitude of 15.5 in 2002. It was originally classified as 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 th ...

, but it may be a

supernova impostor Supernova impostors are stellar explosions that appear at first to be a supernova but do not destroy their progenitor stars. As such, they are a class of extra-powerful novae. They are also known as Type V supernovae, Eta Carinae analogs, and gia ...

, like SN 2008S.

Gallery

NGC 4242 GALEX WikiSky.jpg, NGC 4242 by

GALEX Galaxy Evolution Explorer (GALEX or Explorer 83 or SMEX-7) was a NASA orbiting space telescope designed to observe the universe in ultraviolet wavelengths to measure the history of star formation in the universe. In addition to paving the way ...

NGC4242 - SDSS DR14 (panorama).jpg, NGC 4242 by the Sloan Digital Sky Survey NGC 4242 hst 06232 R814GB450 .png,

image of NGC 4242.

References

External links

* {{DEFAULTSORT:NGC 4242 4242 07323 039423 Intermediate spiral galaxies Canes Venatici Canes II Group