IC 1459 (also catalogued as ''IC 5265'') is an

elliptical galaxy 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 R ...

located in the constellation Grus. It is located at a distance of circa 85 million

light-year 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 ...

s from Earth, which, given its apparent dimensions, means that IC 1459 is about 130,000 light-years across. It was discovered by

Edward Emerson Barnard Edward Emerson Barnard (December 16, 1857 – February 6, 1923) was an American astronomer. He was commonly known as E. E. Barnard, and was recognized as a gifted observational astronomer. He is best known for his discovery of the high proper mo ...

in 1892.

Characteristics

IC 1459 is a giant elliptical galaxy. In its core has been observed a fast counter-rotating stellar component, with an estimated total mass of . The stars of this component have circular orbits on a flat disk with a radius of less than two arcseconds. It has been suggested that the stars of the counterrotating disk are of external origin, either by the accretion of a stellar satellite or of a dense

molecular cloud A molecular cloud, sometimes called a stellar nursery (if star formation is occurring within), is a type of interstellar cloud, the density and size of which permit absorption nebulae, the formation of molecules (most commonly molecular hydrogen ...

from which the stars were created. The galaxy also features multiple shells and disturbed

isophote In geometry, an isophote is a curve on an illuminated surface that connects points of equal brightness. One supposes that the illumination is done by parallel light and the brightness is measured by the following scalar product: :b(P)= \vec n(P) ...

s, which indicate that it has accreted material, probably by the

merger Mergers and acquisitions (M&A) are business transactions in which the ownership of companies, other business organizations, or their operating units are transferred to or consolidated with another company or business organization. As an aspect ...

of smaller galaxies with the elliptical galaxy. Enhanced photography revealed the presence of a diffuse spiral pattern at the outer regions of IC 1459. It has been suggested that a merger started a

starburst MicroPro International Corporation was an American software company founded in 1978 in San Rafael, California. They are best known as the publisher of WordStar, a popular early word processor for personal computers. History Founding and early su ...

event in IC 1459. The total duration of this event has not been well constrained, but it is estimated it lasted less than 80 million years. Young stars make up approximately 3% of the total stellar population of the galaxy. They have an average age of 400 million years.

Metallicity In astronomy, metallicity is the abundance of elements present in an object that are heavier than hydrogen and helium. Most of the normal physical matter in the Universe is either hydrogen or helium, and astronomers use the word ''"metals"'' as a ...

has been found to decrease as the radial distance from the center increases. The nucleus of IC 1459 is

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 has been characterised 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+. ...

based on its optical

spectrum A spectrum (plural ''spectra'' or ''spectrums'') is a condition that is not limited to a specific set of values but can vary, without gaps, across a continuum. The word was first used scientifically in optics to describe the rainbow of colors i ...

. The most accepted theory for the power source of active galactic nuclei is the presence of an

accretion disk An accretion disk is a structure (often a circumstellar disk) formed by diffuse material in orbital motion around a massive central body. The central body is typically a star. Friction, uneven irradiance, magnetohydrodynamic effects, and other fo ...

around a supermassive black hole. In the centre of IC 1459 lies 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 ...

with an estimated mass based on stellar velocities. Estimates of the mass of the black hole based on gas kinematics are lower, from (1-4) × 10⁸ to 10⁹ , although the presence of non-gravitational forces acting on the circumnuclear gas renders them less accurate. The disturbed kinematics of the circumnuclear gas may be caused by an outflow. In the circumnuclear region there is also dust with irregular distribution, indicating nonequilibrium motions. The galaxy is characterised as low-power radio loud, with

gigahertz The hertz (symbol: Hz) is the unit of frequency in the International System of Units (SI), equivalent to one event (or cycle) per second. The hertz is an SI derived unit whose expression in terms of SI base units is s−1, meaning that one h ...

-peaked spectrum, and has two symmetrical radio jets. In a 3.5 year observation period, the galaxy showed little variability. The galaxy also has weak

X-ray An X-ray, or, much less commonly, X-radiation, is a penetrating form of high-energy electromagnetic radiation. Most X-rays have a wavelength ranging from 10 picometers to 10 nanometers, corresponding to frequencies in the range 30&nb ...

emission. The nucleus appears unabsorbed in lower energy X-ray, with X-ray luminosity ergs s-1, while the Fe-Kα fluorescence line, is not strong. The

infrared Infrared (IR), sometimes called infrared light, is electromagnetic radiation (EMR) with wavelengths longer than those of visible light. It is therefore invisible to the human eye. IR is generally understood to encompass wavelengths from around ...

emission of the nucleus is also less than the one expected by an AGN hidden by a dust

torus In geometry, a torus (plural tori, colloquially donut or doughnut) is a surface of revolution generated by revolving a circle in three-dimensional space about an axis that is coplanar with the circle. If the axis of revolution does not tou ...

. This indicates that the AGN is seen unobstructed. The galaxy possess an X-ray halo, whose modelling indicated the presence of

dark matter Dark matter is a hypothetical form of matter thought to account for approximately 85% of the matter in the universe. Dark matter is called "dark" because it does not appear to interact with the electromagnetic field, which means it does not ab ...

at a distance larger than 3 effective radii. In images by the

Hubble Space Telescope The Hubble Space Telescope (often referred to as HST or Hubble) is a space telescope that was launched into low Earth orbit in 1990 and remains in operation. It was not the first space telescope, but it is one of the largest and most versa ...

, 199

globular cluster A globular cluster is a spheroidal conglomeration of stars. Globular clusters are bound together by gravity, with a higher concentration of stars towards their centers. They can contain anywhere from tens of thousands to many millions of membe ...

s were recognised, with an indication of a decrease of their number near the core and statistically non-significant evidence of dimodial color distribution.

Nearby galaxies

IC 1459 is the brightest galaxy in a

galaxy group A galaxy group or group of galaxies (GrG) is an aggregation of galaxies comprising about 50 or fewer gravitationally bound members, each at least as luminous as the Milky Way (about 1010 times the luminosity of the Sun); collections of galaxies ...

known as the IC 1459 group. It is a loose group centred at IC 1459 with a large number of spiral galaxies. Other members include NGC 7418, NGC 7418A, NGC 7421, IC 5264, IC 5269, IC 5269B, IC 5270, and IC 5273. IC 5264 lies 6.5 arcminutes south of IC 1459. This group, along with the NGC 7582 group form the Grus cloud, a region of elevated galaxy density. The Grus cloud, along with the nearby Pavo-Indus cloud, lies between the

Local 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 ...

and

Pavo–Indus Supercluster The Pavo-Indus Supercluster is a neighboring supercluster located about away in the constellations of Pavo, Indus, and Telescopium. The supercluster contains three main clusters, Abell 3656, Abell 3698, and Abell 3742. Other groups and clust ...

. The group features both diffuse X-ray emission from the intergalactic medium and HI emission. Based on the presence of both it has been suggested that the group is in its early stages of assembling from different subgroups. Three HI clouds have been found to be associated with the group, two located near IC 5270 and one near NGC 7418. These HI clouds are believed to have formed from gas stripped from the galaxies as a result of

interactions Interaction is action that occurs between two or more objects, with broad use in philosophy and the sciences. It may refer to: Science * Interaction hypothesis, a theory of second language acquisition * Interaction (statistics) * Interactions o ...

Gallery

File:2MASS IC 1459.jpg,

2MASS The Two Micron All-Sky Survey, or 2MASS, was an astronomical survey of the whole sky in infrared light. It took place between 1997 and 2001, in two different locations: at the U.S. Fred Lawrence Whipple Observatory on Mount Hopkins, Arizona, and ...

image of IC 1459

References

External links

IC 1459 on SIMBAD
{{DEFAULTSORT:IC 1459 Elliptical galaxies Shell galaxies Radio galaxies Grus (constellation)

1459 Year 1459 ( MCDLIX) was a common year starting on Monday (link will display the full calendar) of the Julian calendar. Events January–December * January 18 – The Order of Our Lady of Bethlehem is founded by Pope Pius II, to def ...

70090 Astronomical objects discovered in 1892 Discoveries by Edward Emerson Barnard

Characteristics

Nearby galaxies

Gallery

See also

References

External links