Low surface brightness galaxy

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An image of NGC 45, a low surface brightness spiral galaxy, by GALEX. NGC 45 GALEX WikiSky.jpg
An image of NGC 45, a low surface brightness spiral galaxy, by GALEX.
UGC 477 is located over 110 million light-years away in the constellation of Pisces. Hiding in the night sky.jpg
UGC 477 is located over 110 million light-years away in the constellation of Pisces.

A low-surface-brightness galaxy, or LSB galaxy, is a diffuse galaxy with a surface brightness that, when viewed from Earth, is at least one magnitude lower than the ambient night sky.

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Most LSBs are dwarf galaxies, and most of their baryonic matter is in the form of neutral gaseous hydrogen, rather than stars. They appear to have over 95% of their mass as non-baryonic dark matter. There appears to be little supernova (SN) activity in these galaxies,[ citation needed ] although LSB galaxy IC 217 hosted 2014cl. [2] [3]

Rotation curve measurements indicate an extremely high mass-to-light ratio, meaning that stars and luminous gas contribute only very little to the overall mass balance of an LSB. The centers of LSBs show no large overdensities in stars, unlike e.g. the bulges of normal spiral galaxies. Therefore, they seem to be dark-matter-dominated even in their centers, which makes them excellent laboratories for the study of dark matter.

In comparison to the high-surface-brightness galaxies, LSBs are mainly isolated field galaxies, found in regions devoid of other galaxies. In their past, they had fewer tidal interactions or mergers with other galaxies, which could have triggered enhanced star formation. This is an explanation for the small stellar content.

LSB galaxies were theorized to exist in 1976 by Mike Disney.

Giant low-surface-brightness galaxies

Giant low surface brightness (GLSB) galaxies are among the most massive known spiral galaxies in the Universe. [4] They have very faint stellar disks that are very rich in neutral hydrogen but low in star formation and thus low in surface brightness. [4] Such galaxies often have bright bulges that can host low luminosity active galactic nuclei. [4] GLSB galaxies are usually isolated systems that rarely interact with other galaxies. [4] The first LSB galaxy verified to exist was Malin 1, discovered in 1986. As such, it was also the first giant LSB galaxy identified. At the time of its discovery, it was the largest spiral galaxy known (by scale-length measurement). [5] [6]

UGC 1382 was previously thought to be an elliptical galaxy, but low-brightness spiral arms were later detected. UGC 1382 is much closer to Earth than Malin 1. [7]

Examples

See also

Related Research Articles

<span class="mw-page-title-main">Galaxy</span> Large gravitationally bound system of stars and interstellar matter

A galaxy is a system of stars, stellar remnants, interstellar gas, dust, and dark matter bound together by gravity. The word is derived from the Greek galaxias (γαλαξίας), literally 'milky', a reference to the Milky Way galaxy that contains the Solar System. Galaxies, averaging an estimated 100 million stars, range in size from dwarfs with less than a thousand stars, to the largest galaxies known – supergiants with one hundred trillion stars, each orbiting its galaxy's center of mass. Most of the mass in a typical galaxy is in the form of dark matter, with only a few percent of that mass visible in the form of stars and nebulae. Supermassive black holes are a common feature at the centres of galaxies.

<span class="mw-page-title-main">Coma Berenices</span> Constellation in the northern hemisphere

Coma Berenices is an ancient asterism in the northern sky, which has been defined as one of the 88 modern constellations. It is in the direction of the fourth galactic quadrant, between Leo and Boötes, and it is visible in both hemispheres. Its name means "Berenice's Hair" in Latin and refers to Queen Berenice II of Egypt, who sacrificed her long hair as a votive offering. It was introduced to Western astronomy during the third century BC by Conon of Samos and was further corroborated as a constellation by Gerardus Mercator and Tycho Brahe. It is the only modern constellation named for a historic person.

<span class="mw-page-title-main">Galaxy rotation curve</span> Observed discrepancy in galactic angular momenta

The rotation curve of a disc galaxy is a plot of the orbital speeds of visible stars or gas in that galaxy versus their radial distance from that galaxy's centre. It is typically rendered graphically as a plot, and the data observed from each side of a spiral galaxy are generally asymmetric, so that data from each side are averaged to create the curve. A significant discrepancy exists between the experimental curves observed, and a curve derived by applying gravity theory to the matter observed in a galaxy. Theories involving dark matter are the main postulated solutions to account for the variance.

<span class="mw-page-title-main">Triangulum Galaxy</span> Spiral galaxy in the constellation Triangulum

The Triangulum Galaxy is a spiral galaxy 2.73 million light-years (ly) from Earth in the constellation Triangulum. It is catalogued as Messier 33 or NGC (New General Catalogue) 598. With the D25 isophotal diameter of 18.74 kiloparsecs (61,100 light-years), the Triangulum Galaxy is the third-largest member of the Local Group of galaxies, behind the Andromeda Galaxy and the Milky Way.

<span class="mw-page-title-main">Elliptical galaxy</span> Spherical or ovoid mass of stars

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.

<span class="mw-page-title-main">Spiral galaxy</span> Class of galaxy that has spiral structures extending from their cores.

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.

<span class="mw-page-title-main">Lenticular galaxy</span> Class of galaxy between an elliptical galaxy 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.

A galactic halo is an extended, roughly spherical component of a galaxy which extends beyond the main, visible component. Several distinct components of a galaxy comprise its halo:

<span class="mw-page-title-main">Messier 63</span> Spiral galaxy in the constellation Canes Venatici

Messier 63 or M63, also known as NGC 5055 or the seldom-used Sunflower Galaxy, is a spiral galaxy in the northern constellation of Canes Venatici with approximately 400 billion stars. M63 was first discovered by the French astronomer Pierre Méchain, then later verified by his colleague Charles Messier on 14 June 1779. The galaxy became listed as object 63 in the Messier Catalogue. In the mid-19th century, Anglo-Irish astronomer Lord Rosse identified spiral structures within the galaxy, making this one of the first galaxies in which such structure was identified.

<span class="mw-page-title-main">Messier 94</span> Galaxy in the constellation Canes Venatici

Messier 94 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 a barred spiral galaxy, the "bar" structure appears to be more oval-shaped. The galaxy has two ring structures.

<span class="mw-page-title-main">NGC 891</span> Galaxy in the constellation Andromeda

NGC 891 is an edge-on unbarred spiral galaxy about 30 million light-years away in the constellation Andromeda. It was discovered by William Herschel on October 6, 1784. The galaxy is a member of the NGC 1023 group of galaxies in the Local Supercluster. It has an H II nucleus.

<span class="mw-page-title-main">Milky Way</span> Galaxy containing the Solar System

The Milky Way is the galaxy that includes the 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.

<span class="mw-page-title-main">Outline of astronomy</span> Overview of the scientific field of astronomy

The following outline is provided as an overview of and topical guide to astronomy:

<span class="mw-page-title-main">NGC 6872</span> Galaxy in the constellation Pavo

NGC 6872, also known as the Condor Galaxy, is a large barred spiral galaxy of type SB(s)b pec in the constellation Pavo. It is 212 million light-years (65 Mpc) from Earth. NGC 6872 is interacting with the lenticular galaxy IC 4970, which is less than one twelfth as large. The galaxy has two elongated arms with a diameter based on ultraviolet light of over 522,000 light-years (160,000 pc), and a D25.5 isophotal diameter of over 717,000 light-years (220,000 pc), making it the largest known spiral galaxy. It was discovered on 27 June 1835 by English astronomer John Herschel.

<span class="mw-page-title-main">Gamma-ray burst progenitors</span> Types of celestial objects that can emit gamma-ray bursts

Gamma-ray burst progenitors are the types of celestial objects that can emit gamma-ray bursts (GRBs). GRBs show an extraordinary degree of diversity. They can last anywhere from a fraction of a second to many minutes. Bursts could have a single profile or oscillate wildly up and down in intensity, and their spectra are highly variable unlike other objects in space. The near complete lack of observational constraint led to a profusion of theories, including evaporating black holes, magnetic flares on white dwarfs, accretion of matter onto neutron stars, antimatter accretion, supernovae, hypernovae, and rapid extraction of rotational energy from supermassive black holes, among others.

<span class="mw-page-title-main">Malin 1</span> Spiral galaxy in the constellation Coma Berenices

Malin 1 is a giant low surface brightness (LSB) spiral galaxy. It is located 1.19 billion light-years (366 Mpc) away in the constellation Coma Berenices, near the North Galactic Pole. As of February 2015, it is the largest known spiral galaxy, with an approximate diameter of 650,000 light-years (200,000 pc), thus over six times the diameter of our Milky Way. It was discovered by astronomer David Malin in 1986 and is the first LSB galaxy verified to exist. Its high surface brightness central spiral is 30,000 light-years (9,200 pc) across, with a bulge of 10,000 light-years (3,100 pc). The central spiral is a SB0a type barred-spiral.

<span class="mw-page-title-main">UGC 2885</span> Large barred spiral galaxy in the constellation Perseus

UGC 2885 is a large barred spiral galaxy of type SA(rs)c in the constellation Perseus. It is 232 million light-years (71 Mpc) from Earth and measures 463,000 ly (142,000 pc) across, making it one of the largest known spiral galaxies. It is also a possible member of the Pisces-Perseus supercluster.

<span class="mw-page-title-main">UGC 6614</span> Giant spiral galaxy

UGC 6614 is a giant spiral galaxy located about 330 million light-years away in the constellation Leo. It has an estimated diameter of nearly 300,000 light-years.

<span class="mw-page-title-main">NGC 3883</span> Galaxy in the constellation Leo

NGC 3883 is a large low surface brightness spiral galaxy located about 330 million light-years away in the constellation Leo. NGC 3883 has a prominent bulge but does not host an AGN. The galaxy also has flocculent spiral arms in its disk. It was discovered by astronomer William Herschel on April 13, 1785 and is a member of the Leo Cluster.

<span class="mw-page-title-main">NGC 765</span> Galaxy in the constellation Aries

NGC 765 is an intermediate spiral galaxy located in the constellation Aries. It is located at a distance of circa 220 million light years from Earth, which, given its apparent dimensions, means that NGC 765 is about 195,000 light years across. It was discovered by Albert Marth on October 8, 1864. The galaxy has an extensive hydrogen (HI) disk with low surface brightness, whose diameter is estimated to be 240 kpc.

References

  1. "Hiding in the night sky" . Retrieved 4 April 2016.
  2. D. Monnier Ragaigne; W. van Driel; S.E. Schneider; T.H. Jarrett; C. Balkowski (July 2003). "A search for Low Surface Brightness galaxies in the near-infrared I. Selection of the sample". Astronomy and Astrophysics. 405: 99–109. arXiv: astro-ph/0304380 . Bibcode:2003A&A...405...99M. doi: 10.1051/0004-6361:20030585 .
  3. L. Gonzalez; M. Hamuy; R. Antezana (August 2014). "Supernova 2014cl in IC 217". Central Bureau Electronic Telegrams. 3950: 1. Bibcode:2014CBET.3950....1G.
  4. 1 2 3 4 Mousumi Das (March 2013). "Giant Low Surface Brightness Galaxies: Evolution in Isolation". Journal of Astrophysics and Astronomy. 34 (1): 19–31. arXiv: 1310.6495 . Bibcode:2013JApA...34...19D. doi:10.1007/s12036-013-9166-8. S2CID   118546432.
  5. 1 2 3 Scientific American, "The Ghostliest Galaxies", GD Bothun, Vol. 276, No. 2, February 1997, pp.40-45, Bibcode : 1997SciAm.276b..40B
  6. Ken Crosswell, "Malin 1: A Bizarre Galaxy Gets Slightly Less So", 22 January 2007
  7. "Surprise: Small elliptical galaxy actually a giant disk". 11 July 2016. Retrieved 12 July 2016.