Starburst galaxy

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The Antennae Galaxies are an example of a starburst galaxy occurring from the collision of NGC 4038/NGC 4039. Credit: NASA/ESA. Antennae galaxies xl.jpg
The Antennae Galaxies are an example of a starburst galaxy occurring from the collision of NGC 4038/NGC 4039. Credit: NASA/ESA.

A starburst galaxy is a galaxy undergoing an exceptionally high rate of star formation, as compared to the long-term average rate of star formation in the galaxy or the star formation rate observed in most other galaxies. For example, the star formation rate of the Milky Way galaxy is approximately 3 M/yr; however, starburst galaxies can experience star formation rates that are more than a factor of 33 times greater. [1] In a starburst galaxy, the rate of star formation is so large that the galaxy will consume all of its gas reservoir, from which the stars are forming, on a timescale much shorter than the age of the galaxy. As such, the starburst nature of a galaxy is a phase, and one that typically occupies a brief period of a galaxy's evolution. The majority of starburst galaxies are in the midst of a merger or close encounter with another galaxy. Starburst galaxies include M82, NGC 4038/NGC 4039 (the Antennae Galaxies), and IC 10.

Contents

Definition

Light and dust in a nearby starburst galaxy Light and dust in a nearby starburst galaxy.jpg
Light and dust in a nearby starburst galaxy

Starburst galaxies are defined by these three interrelated factors:

  1. The rate at which the galaxy is currently converting gas into stars (the star-formation rate, or SFR).
  2. The available quantity of gas from which stars can be formed.
  3. A comparison of the timescale on which star formation will consume the available gas with the age or rotation period of the galaxy.

Commonly used definitions include:

Triggering mechanisms

Mergers and tidal interactions between gas-rich galaxies play a large role in driving starbursts. Galaxies in the midst of a starburst frequently show tidal tails, an indication of a close encounter with another galaxy, or are in the midst of a merger. Interactions between galaxies that do not merge can trigger unstable rotation modes, such as the bar instability, which causes gas to be funneled towards the nucleus and ignites bursts of star formation near the galactic nucleus. It has been shown that there is a strong correlation between the lopsidedness of a galaxy and the youth of its stellar population, with more lopsided galaxies having younger central stellar populations. [3] As lopsidedness can be caused by tidal interactions and mergers between galaxies, this result gives further evidence that mergers and tidal interactions can induce central star formation in a galaxy and drive a starburst.

Types

Artist's impression of a galaxy undergoing a starburst. Artist's impression of a galaxy undergoing a starburst.jpg
Artist's impression of a galaxy undergoing a starburst.

Classifying types of starburst galaxies is difficult since starburst galaxies do not represent a specific type in and of themselves. Starbursts can occur in disk galaxies, and irregular galaxies often exhibit knots of starburst spread throughout the irregular galaxy. Nevertheless, astronomers typically classify starburst galaxies based on their most distinct observational characteristics. Some of the categorizations include:

SBS 1415+437 is a WR galaxy located about 45 million light-years from Earth. Hubble View- Wolf-Rayet Stars, Intense and Short-Lived (18731205164).jpg
SBS 1415+437 is a WR galaxy located about 45 million light-years from Earth.

Ingredients

Messier 82 is the prototype nearby starburst galaxy about 12 million light-years away in the constellation Ursa Major. Messier 82 HST.jpg
Messier 82 is the prototype nearby starburst galaxy about 12 million light-years away in the constellation Ursa Major.

Firstly, a starburst galaxy must have a large supply of gas available to form stars. The burst itself may be triggered by a close encounter with another galaxy (such as M81/M82), a collision with another galaxy (such as the Antennae), or by another process which forces material into the centre of the galaxy (such as a stellar bar).

The inside of the starburst is quite an extreme environment. The large amounts of gas mean that very massive stars are formed. Young, hot stars ionize the gas (mainly hydrogen) around them, creating H II regions. Groups of very hot stars are known as OB associations. These stars burn very bright and very fast, and are quite likely to explode at the end of their lives as supernovae.

After the supernova explosion, the ejected material expands and becomes a supernova remnant. These remnants interact with the surrounding environment within the starburst (the interstellar medium) and can be the site of naturally occurring masers.

Studying nearby starburst galaxies can help us determine the history of galaxy formation and evolution. Large numbers of the very distant galaxies seen, for example, in the Hubble Deep Field are known to be starbursts, but they are too far away to be studied in any detail. Observing nearby examples and exploring their characteristics can give us an idea of what was happening in the early universe as the light we see from these distant galaxies left them when the universe was much younger (see redshift). However, starburst galaxies seem to be quite rare in our local universe, and are more common further away – indicating that there were more of them billions of years ago. All galaxies were closer together then, and therefore more likely to be influenced by each other's gravity. More frequent encounters produced more starbursts as galactic forms evolved with the expanding universe.

Examples

Artist's impression of gas fueling distant starburst galaxies. Artist's impression of gas fueling distant starburst galaxies.jpg
Artist's impression of gas fueling distant starburst galaxies.

M82 is the archetypal starburst galaxy. Its high level of star formation is due to a close encounter with the nearby spiral M81. Maps of the regions made with radio telescopes show large streams of neutral hydrogen connecting the two galaxies, also as a result of the encounter. Radio images of the central regions of M82 also show a large number of young supernova remnants, left behind when the more massive stars created in the starburst came to the end of their lives. The Antennae is another starburst system, detailed by a Hubble picture, released in 1997.

List of starburst galaxies

GalaxyTypeNotesRefs
M82 I0Archetype starburst galaxy
The Antennae SB(s)m pec /
SA(s)m pec
This is actually two colliding galaxies
IC 10 dIrrMild starburst galaxy
HXMM01 Extreme starburst merging galaxies
HFLS3 Unusually large intense starburst galaxy
NGC 1569 IBmDwarf galaxy undergoing a galaxy-wide starburst
NGC 2146 SB(s)ab pec
NGC 1705 SA0 pec
NGC 1614 SB(s)c pecMerging with another galaxy
NGC 6946 SAB(rs)cdAlso known as fireworks galaxy for frequent supernovae
Baby Boom Galaxy Brightest starburst galaxy in distant universe
Centaurus A E(p)Only known case of an "Elliptical Starburst" Galaxy
Large Magellanic Cloud Being disrupted by the Milky Way
Haro 11 Emits Lyman continuum photons
Sculptor Galaxy SAB(s)cNearest starburst galaxy., [8] [9]
Kiso 5639 Also known as the 'Skyrocket Galaxy' due to its appearance, it's a small irregular galaxy which is just beginning a major starburst [10]

[11]

This video zooms into distant galaxies undergoing a starburst in a region of sky known as the Extended Chandra Deep Field South, in the constellation of Fornax (The Furnace).
This video pans over the same galaxies.

See also

Notes

  1. 1958-, Schneider, P. (Peter) (2010). Extragalactic astronomy and cosmology : an introduction. Berlin: Springer. ISBN   9783642069710. OCLC   693782570.CS1 maint: numeric names: authors list (link)
  2. "Light and dust in a nearby starburst galaxy". ESA/Hubble. Retrieved 4 April 2013.
  3. Reichard, T.A.; Heckman, T.M. (January 2009). "The Lopsidedness of Present-Day Galaxies: Connections to the Formation of Stars, the Chemical Evolution of Galaxies, and the Growth of Black Holes". The Astrophysical Journal. 691 (2): 1005–1020. arXiv: 0809.3310 . Bibcode:2009ApJ...691.1005R. doi:10.1088/0004-637X/691/2/1005. S2CID   16680136.
  4. "Entire galaxies feel the heat from newborn stars". ESA/Hubble Press Release. Retrieved 30 April 2013.
  5. "Intense and short-lived" . Retrieved 29 June 2015.
  6. Physical Properties of Wolf–Rayet Stars
  7. "ALMA Finds Huge Hidden Reservoirs of Turbulent Gas in Distant Galaxies – First detection of CH+ molecules in distant starburst galaxies provides insight into star formation history of the Universe". www.eso.org. Retrieved 31 August 2017.
  8. Sakamoto, Kazushi; Ho, Paul T. P.; Iono, Daisuke; Keto, Eric R.; Mao, Rui-Qing; Matsushita, Satoki; Peck, Alison B.; Wiedner, Martina C.; Wilner, David J.; Zhao, Jun-Hui (10 January 2006). "Molecular Superbubbles in the Starburst Galaxy NGC 253". The Astrophysical Journal. 636 (2): 685–697. arXiv: astro-ph/0509430 . Bibcode:2006ApJ...636..685S. doi:10.1086/498075. S2CID   14273657.
  9. Lucero, D. M.; Carignan, C.; Elson, E. C.; Randriamampandry, T. H.; Jarrett, T. H.; Oosterloo, T. A.; Heald, G. H. (1 December 2015). "HI observations of the nearest starburst galaxy NGC 253 with the SKA precursor KAT-7". MNRAS. 450: 3935–3951. arXiv: 1504.04082 . doi:10.1093/mnras/stv856.
  10. "Hubble Reveals Stellar Fireworks in 'Skyrocket' Galaxy". 28 June 2016.
  11. "Check out what the @NASAHubble Space Telescope looked at on my birthday! #Hubble30".
  12. "A galaxy fit to burst". www.spacetelescope.org. ESA/Hubble. Retrieved 18 July 2016.
  13. "A lonely birthplace" . Retrieved 15 July 2016.
  14. "A swirl of star formation". ESA/Hubble Picture of the Week. Retrieved 22 May 2013.

Related Research Articles

Galaxy Gravitationally bound astronomical structure

A galaxy is a gravitationally bound system of stars, stellar remnants, interstellar gas, dust, and dark matter. The word is derived from the Greek galaxias (γαλαξίας), literally "milky", a reference to the Milky Way. Galaxies range in size from dwarfs with just a few hundred million stars to giants with one hundred trillion stars, each orbiting its galaxy's center of mass.

NGC 6240 Galaxy merger remnant and ultraluminous infrared galaxy in the constellation Ophiuchus

NGC 6240, also known as the Starfish Galaxy, is a nearby ultraluminous infrared galaxy (ULIRG) in the constellation Ophiuchus. The galaxy is the remnant of a merger between three smaller galaxies. The collision between the three progenitor galaxies has resulted in a single, larger galaxy with two distinct nuclei and a highly disturbed structure, including faint extensions and loops.

Elliptical galaxy Galaxy having an approximately ellipsoidal shape and a smooth, nearly featureless brightness profile

An elliptical galaxy is a type of galaxy with an approximately ellipsoidal shape and a smooth, nearly featureless image. They are one of the four main classes of galaxy described by Edwin Hubble in his Hubble sequence and 1936 work The Realm of the Nebulae, along with spiral and lenticular galaxies. Elliptical (E) galaxies are, together with lenticular galaxies (S0) with their large-scale disks, and ES galaxies with their intermediate scale disks, a subset of the "early-type" galaxy population.

Spiral galaxy Class of galaxy having a number of arms of younger stars

Spiral galaxies form a class of galaxy originally described by Edwin Hubble in his 1936 work The Realm of the Nebulae and, as such, form part of the Hubble sequence. Most spiral galaxies consist of a flat, rotating disk containing stars, gas and dust, and a central concentration of stars known as the bulge. These are often surrounded by a much fainter halo of stars, many of which reside in globular clusters.

Lenticular galaxy Type of galaxy intermediate between an elliptical and a spiral galaxy

A lenticular galaxy is a type of galaxy intermediate between an elliptical and a spiral galaxy in galaxy morphological classification schemes. It contains a large-scale disc but does not have large-scale spiral arms. Lenticular galaxies are disc galaxies that have used up or lost most of their interstellar matter and therefore have very little ongoing star formation. They may, however, retain significant dust in their disks. As a result, they consist mainly of aging stars. Despite the morphological differences, lenticular and elliptical galaxies share common properties like spectral features and scaling relations. Both can be considered early-type galaxies that are passively evolving, at least in the local part of the Universe. Connecting the E galaxies with the S0 galaxies are the ES galaxies with intermediate-scale discs.

Dwarf galaxy Small galaxy composed of up to several billion stars

A dwarf galaxy is a small galaxy composed of about 1000 up to several billion stars, as compared to the Milky Way's 200–400 billion stars. The Large Magellanic Cloud, which closely orbits the Milky Way and contains over 30 billion stars, is sometimes classified as a dwarf galaxy; others consider it a full-fledged galaxy. Dwarf galaxies' formation and activity are thought to be heavily influenced by interactions with larger galaxies. Astronomers identify numerous types of dwarf galaxies, based on their shape and composition.

Sculptor Galaxy Intermediate spiral galaxy in the constellation Sculptor

The Sculptor Galaxy is an intermediate spiral galaxy in the constellation Sculptor. The Sculptor Galaxy is a starburst galaxy, which means that it is currently undergoing a period of intense star formation.

NGC 3603 Open cluster in the constellation Carina

NGC 3603 is a nebula situated in the Carina–Sagittarius Arm of the Milky Way around 20,000 light-years away from the Solar System. It is a massive H II region containing a very compact open cluster HD 97950.

Starburst region Region of faster than normal star formation

A starburst is an astrophysical process that involves star formation 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 has a star formation rate estimated to be 3600 solar masses per million years compared to the star formation rate of the entire Milky Way of about seven million solar masses 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 to carbon monoxide emission-lines than are usually observed.

Antennae Galaxies Interacting galaxy in the constellation Corvus

The Antennae Galaxies are a pair of interacting galaxies in the constellation Corvus. They are currently going through a starburst phase, in which the collision of clouds of gas and dust, with entangled magnetic fields, causes rapid star formation. They were discovered by William Herschel in 1785.

Interacting galaxy Galaxies whose gravitational fields result in the disturbance of one another.

Interacting galaxies are galaxies whose gravitational fields result in a disturbance of one another. An example of a minor interaction is a satellite galaxy disturbing the primary galaxy's spiral arms. An example of a major interaction is a galactic collision, which may lead to a galaxy merger.

Luminous infrared galaxies or LIRGs are galaxies with luminosities, the measurement of brightness, above 1011 L. They are also referred to as submillimeter galaxies (SMGs) through their normal method of detection. LIRGs are more abundant than starburst galaxies, Seyfert galaxies and quasi-stellar objects at comparable luminosity. Infrared galaxies emit more energy in the infrared than at all other wavelengths combined. A LIRG's luminosity is 100 billion times that of our sun.

Galaxy merger Merger whereby at least two galaxies collide

Galaxy mergers can occur when two 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 involved. The exact effects of such mergers depend on a wide variety of parameters such as collision angles, speeds, and relative size/composition, and are currently an extremely active area of research. Galaxy mergers are important because the merger rate is a fundamental measurement of galaxy evolution. The merger rate also provides astronomers with clues about how galaxies bulked up over time.

Pea galaxy Possibly a type of luminous blue compact galaxy which is undergoing very high rates of star formation

A Pea galaxy, also referred to as a Pea or Green Pea, might be a type of luminous blue compact galaxy that is undergoing very high rates of star formation. Pea galaxies are so-named because of their small size and greenish appearance in the images taken by the Sloan Digital Sky Survey (SDSS).

Westerhout 43 Region of star formation in the constellation Aquila

Westerhout 43, also known as W43, is a region of star formation of our galaxy located in the constellation of Aquila at a distance of 6 kilo-parsecs of the Sun, that is considered the region of the Milky Way that is most actively forming stars. Despite this, however, it is so heavily obscured by the interstellar dust that it is totally invisible in the optical and must be studied using other wavelengths that are not affected by it, such as the infrared or the radio waves.

Haro 11 Galaxy in the constellation Sculptor

Haro 11 (H11) is a small galaxy at a distance of 300,000,000 light-years (redshift z=0.020598). It is situated in the southern constellation of Sculptor. Visually, it appears to be an irregular galaxy, as the ESO image to the right shows. H11 is named after Guillermo Haro, a Mexican astronomer who first included it in a study published in 1956 about blue galaxies. H11 is a starburst galaxy that has 'super star clusters' within it and is one of nine galaxies in the local universe known to emit Lyman continuum photons (LyC).

NGC 1614 Spiral galaxy in the constellation Eridanus

NGC 1614 is the New General Catalogue identifier for a spiral galaxy in the equatorial constellation of Eridanus. It was discovered on December 29, 1885 by American astronomer Lewis Swift, who described it in a shorthand notation as: pretty faint, small, round, a little brighter middle. The nebula was then catalogued by Danish-Irish astronomer J. L. E. Drayer in 1888. When direct photography became available, it was noted that this galaxy displayed some conspicuous peculiarities. American astronomer Halton Arp included it in his 1966 Atlas of Peculiar Galaxies. In 1971, Swiss astronomer Fritz Zwicky described it as a "blue post-eruptive galaxy, compact patchy core, spiral plumes, long blue jet SSW".

NGC 1140 Irregular galaxy in Eridanus

NGC 1140 is an irregular galaxy in the southern constellation of Eridanus. Estimates made using the Tully–Fisher method put the galaxy at about 59 million light years. It was discovered on 22 November 1786 by William Herschel, and was described as "pretty bright, small, round, stellar" by John Louis Emil Dreyer, the compiler of the New General Catalogue.

NGC 2623 Interacting galaxy in the constellation Cancer

NGC 2623/Arp 243 is an interacting galaxy located in the constellation Cancer. NGC 2623 is the result of two spiral galaxies that have merged. Scientists believe that this situation is similar to what will occur to the Milky Way, which contains our solar system, and the neighboring galaxy, the Andromeda Galaxy in four billion years. Studying this galaxy and its properties have provided scientists with a better idea of the coming collision of the Milky Way and the Andromeda. Due to NGC 2623 being in the late stage of merging, the compression of the gas within the galaxy has led to a large amount of star formation, and to its unique structure of a bright core with two extending tidal tails.

NGC 3256 Peculiar galaxy in the constellation Vela

NGC 3256 is a peculiar galaxy formed from the collision of two separate galaxies in the constellation of Vela. NGC 3256 is located about 100 million light years away and belongs to the Hydra-Centaurus supercluster complex. NGC 3256 provides a nearby template for studying the properties of young star clusters in tidal tails. The system hides a double nucleus and a tangle of dust lanes in the central region. The telltale signs of the collision are two extended luminous tails swirling out from the galaxy. The tails are studded with a particularly high density of star clusters. NGC 3256 is the most luminous galaxy in the infrared spectrum located within z 0.01 from Earth.

References