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A starburst is an astrophysical process that involves 
Starbursts can occur in entire galaxies or just regions of space. A starburst region is a region of space that is undergoing a large amount of star formation. For example, the
A starburst is an astrophysical process that involves star formation
Star formation is the process by which dense regions within molecular clouds in The "medium" is present further soon.-->interstellar space
occurring at a rate that is large compared to the rate that is typically observed. This starburst activity will consume the available interstellar gas supply over a timespan that is much shorter than the lifetime of the galaxy. For example, the nebula NGC 6334
NGC commonly refers to:
* New General Catalogue of Nebulae and Clusters of Stars, a catalogue of deep sky objects in astronomy
NGC may also refer to:
Companies
* NGC Corporation, name of US electric company Dynegy, Inc. from 1995 to 1998
* Nati ...
has a star formation rate estimated to be 3600 solar mass
The solar mass () is a standard unit of mass in astronomy, equal to approximately . It is often used to indicate the masses of other stars, as well as stellar clusters, nebulae, galaxies and black holes. It is approximately equal to the mass ...
es per million years compared to the star formation rate of the entire Milky Way
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 ...
of about seven million solar mass
The solar mass () is a standard unit of mass in astronomy, equal to approximately . It is often used to indicate the masses of other stars, as well as stellar clusters, nebulae, galaxies and black holes. It is approximately equal to the mass ...
es per million years. Due to the high amount of star formation a starburst is usually accompanied by much higher gas pressure and a larger ratio of hydrogen cyanide
Hydrogen cyanide, sometimes called prussic acid, is a chemical compound with the formula HCN and structure . It is a colorless, extremely poisonous, and flammable liquid that boils slightly above room temperature, at . HCN is produced on an ...
to carbon monoxide
Carbon monoxide (chemical formula CO) is a colorless, poisonous, odorless, tasteless, flammable gas that is slightly less dense than air. Carbon monoxide consists of one carbon atom and one oxygen atom connected by a triple bond. It is the simple ...
emission-line
A spectral line is a dark or bright line in an otherwise uniform and continuous spectrum, resulting from emission (electromagnetic radiation), emission or absorption (electromagnetic radiation), absorption of light in a narrow frequency range, ...
s than are usually observed.
Starbursts can occur in entire galaxies or just regions of space. A starburst region is a region of space that is undergoing a large amount of star formation. For example, the Tarantula Nebula
The Tarantula Nebula (also known as 30 Doradus) is a large H II region in the Large Magellanic Cloud (LMC), forming its south-east corner (from Earth's perspective).
Discovery
The Tarantula Nebula was observed by Nicolas-Louis de Lacaille durin ...
is a nebula
A nebula ('cloud' or 'fog' in Latin; pl. nebulae, nebulæ or nebulas) is a distinct luminescent part of interstellar medium, which can consist of ionized, neutral or molecular hydrogen and also cosmic dust. Nebulae are often star-forming regio ...
in the Large Magellanic Cloud
The Large Magellanic Cloud (LMC), or Nubecula Major, is a satellite galaxy of the Milky Way. At a distance of around 50 kiloparsecs (≈160,000 light-years), the LMC is the second- or third-closest galaxy to the Milky Way, after the ...
which has one of the highest star formation rates in the Local Group
The Local Group is the galaxy group that includes the Milky Way.
It has a total diameter of roughly , and a total mass of the order of .
It consists of two collections of galaxies in a "dumbbell" shape: the Milky Way and its satellites form ...
. By contrast, a starburst galaxy is an entire galaxy that is experiencing a very high star formation rate. One notable example is Messier 82
Messier 82 (also known as NGC 3034, Cigar Galaxy or M82) is a starburst galaxy approximately 12 million light-years away in the constellation Ursa Major. It is the second-largest member of the M81 Group, with the D25 isophotal diameter of . It ...
in which the gas pressure is 100 times greater than in the local neighborhood, and it is forming stars at about the same rate as the entire Milky Way
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 ...
in a region only about 600 parsecs across. At this rate M82 will consume its 200 million solar mass
The solar mass () is a standard unit of mass in astronomy, equal to approximately . It is often used to indicate the masses of other stars, as well as stellar clusters, nebulae, galaxies and black holes. It is approximately equal to the mass ...
es of atomic and molecular hydrogen in 100 million years (its free-fall time The free-fall time is the characteristic time that would take a body to collapse under its own gravitational attraction, if no other forces existed to oppose the collapse. As such, it plays a fundamental role in setting the timescale for a wide vari ...
).
Starburst regions can occur in different shapes, for example in Messier 94
Messier 94 (also known as NGC 4736) is a spiral galaxy in the mid- northern constellation Canes Venatici. It was discovered by Pierre Méchain in 1781,
and catalogued by Charles Messier two days later. Although some references describe M94 as ...
the inner ring is a starburst region. Messier 82
Messier 82 (also known as NGC 3034, Cigar Galaxy or M82) is a starburst galaxy approximately 12 million light-years away in the constellation Ursa Major. It is the second-largest member of the M81 Group, with the D25 isophotal diameter of . It ...
has a starburst core of about 600 parsec in diameter. Starbursts are common during galaxy merger
Galaxy mergers can occur when two (or more) galaxies collide. They are the most violent type of galaxy interaction. The gravitational interactions between galaxies and the friction between the gas and dust have major effects on the galaxies i ...
s such as the Antennae Galaxies
The Antennae Galaxies (also known as NGC 4038/NGC 4039 or Caldwell 60/Caldwell 61) are a pair of interacting galaxy, interacting galaxies in the constellation Corvus (constellation), Corvus. They are currently going through a Starburst Galaxies, ...
. In the case of mergers, the starburst can either be local or galaxy-wide depending on the galaxies and how they are merging.
See also
* ** * * *References