NGC 3396 is a peculiar

barred irregular galaxy A barred irregular galaxy is an irregular version of a barred spiral galaxy. Examples include the Large Magellanic Cloud and NGC 6822. Some barred irregular galaxies (like the Large Magellanic Cloud) may be dwarf spiral galaxies, which have been ...

in the constellation

Leo Minor Leo Minor is a small and faint constellation in the northern celestial hemisphere. Its name is Latin for "the smaller lion", in contrast to Leo, the larger lion. It lies between the larger and more recognizable Ursa Major to the north and Le ...

. The galaxy lies about 80 million

light years A light-year, alternatively spelled light year, is a large unit of length used to express astronomical distances and is equivalent to about 9.46 trillion kilometers (), or 5.88 trillion miles ().One trillion here is taken to be 1012 ...

away from Earth, which means, given its apparent dimensions, that NGC 3396 is approximately 85,000 light years across. It was discovered 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 H ...

on December 7, 1785.

Characteristics

NGC 3396 forms an interacting pair with NGC 3395, a

spiral galaxy Spiral galaxies form a class of galaxy originally described by Edwin Hubble in his 1936 work ''The Realm of the Nebulae''tidal tail A tidal tail is a thin, elongated region of stars and interstellar gas that extends into space from a galaxy. Tidal tails occur as a result of galactic tide forces between interacting galaxies. Examples of galaxies with tidal tails include the ...

s are observed. Dynamical modelling of the pair suggests that the two galaxies had a first close encounter in the past, which resulting in gas been stripped from NGC 3395 and forming a tidal tail to the south-east. A second close encounter took place about 50 million years ago, resulting to starburst activity. The two galaxies will most likely

merge Merge, merging, or merger may refer to: Concepts * Merge (traffic), the reduction of the number of lanes on a road * Merge (linguistics), a basic syntactic operation in generative syntax in the Minimalist Program * Merger (politics), the comb ...

in the next 500 million years. The galaxy hosts a number of

HII region An H II region or HII region is a region of interstellar atomic hydrogen that is ionized. It is typically in a molecular cloud of partially ionized gas in which star formation has recently taken place, with a size ranging from one to hundreds ...

s that are star forming with the region of most intense

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

being in the center of the galaxy. The average size of the knots in NGC 3396 is an order of magnitude larger than those in NGC 3395. The central region of NGC 3396 is estimated to host 1,000 to 2,000 Wolf-Rayet stars and tens of thousands of

O-type star An O-type star is a hot, blue-white star of spectral type O in the Yerkes classification system employed by astronomers. They have temperatures in excess of 30,000 kelvin (K). Stars of this type have strong absorption lines of ionised helium, st ...

s. The star formation rate in the circumnuclear is estimated to be 0.15 per year and in the rest of the galaxy 0.39 . The nucleus of the galaxy has been found to be

active Active may refer to: Music * ''Active'' (album), a 1992 album by Casiopea * Active Records, a record label Ships * ''Active'' (ship), several commercial ships by that name * HMS ''Active'', the name of various ships of the British Royal ...

and based on its spectrum it has been categorised as a

LINER A low-ionization nuclear emission-line region (LINER) is a type of galactic nucleus that is defined by its spectral line emission. The spectra typically include line emission from weakly ionized or neutral atoms, such as O, O+, N+, and S+. ...

. Kinematic analysis of the gas indicates there is gas inflow to the centre of the galaxy along its bar and also there is an biconal outflow element that could be galactic wind from 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 ...

in the nucleus.

Nearby galaxies

The NGC 3395/3396 pair is part of the NGC 3430 Group or LGG 218. Other members of the group include the galaxies NGC 3381, NGC 3424, NGC 3430, NGC 3442, and IC 2604. IC 2604 lies 14 arcmin to the south-west of the pair and IC 2608 14 arcmin to the south-east. The group is part of the Leo II groups, which is part of the

Virgo Supercluster The Virgo Supercluster (Virgo SC) or the Local Supercluster (LSC or LS) is a mass concentration of galaxies containing the Virgo Cluster and Local Group, which itself contains the Milky Way and Andromeda galaxies, as well as others. At least ...

References

External links

{{Leo Minor Barred irregular galaxies Interacting galaxies Peculiar galaxies Leo Minor 3396 05935

270 __NOTOC__ Year 270 ( CCLXX) was a common year starting on Saturday (link will display the full calendar) of the Julian calendar. At the time, it was known as the Year of the Consulship of Antiochianus and Orfitus (or, less frequently, year 102 ...

+06-24-018 32434 Discoveries by William Herschel Astronomical objects discovered in 1785