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 ...
of
Columba
Columba or Colmcille; gd, Calum Cille; gv, Colum Keeilley; non, Kolban or at least partly reinterpreted as (7 December 521 – 9 June 597 AD) was an Irish abbot and missionary evangelist credited with spreading Christianity in what is toda ...
, about two degrees to the south and east of Gamma Caeli. It was discovered by Scottish astronomer James Dunlop, who described it as a "faint nebula". The galaxy is a member of the NGC 1808 group, which is part of the larger Dorado Group.
The morphological classification of this galaxy is (R)SAB(s)a, which indicates a spiral galaxy with a weak-bar around the nucleus (SAB), no ring around the bar (s), an outer ring (R), and tightly-wound spiral arms (a). It is inclined by an angle of 57° to the line of sight from the Earth, with the long axis oriented at a position angle of 324°. The disk of gas and stars shows a noticeable warp, and there is a pronounced asymmetry in the distribution of neutral hydrogen and H II regions.
The core region contains a suspected weak active galactic nucleus plus a circumnuclear ring containing
star cluster
Star clusters are large groups of stars. Two main types of star clusters can be distinguished: globular clusters are tight groups of ten thousand to millions of old stars which are gravitationally bound, while open clusters are more loosely clust ...
s and
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 ...
remnants at a distance of from the center. These form a ring of peculiar "hot spots". It was formerly identified as a possible
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 ...
, but evidence now points to
starburst
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History Founding and early su ...
activity in a radius around the center. A probable outflow of gas is directed to the north-east from the nucleus, forming prominent dust lanes. The high level of
NGC 1792
NGC 1792 is a spiral galaxy located in the southern Columba (constellation), Columba constellation. It was discovered by Scottish astronomer James Dunlop on October 4, 1826. This galaxy is located at a distance of about 36.4 million light-ye ...
may indicate a recent, distant tidal interaction between the two.
The type Ia supernova SN 1993af was discovered in November 1993 at east and north of the galactic nucleus.
1808
Events January–March
* January 1
** The importation of slaves into the United States is banned, as the 1807 Act Prohibiting Importation of Slaves takes effect; African slaves continue to be imported into Cuba, and until the island ab ...