NGC 1553 is a

prototypical A prototype is an early sample, model, or release of a product built to test a concept or process. It is a term used in a variety of contexts, including semantics, design, electronics, and Software prototyping, software programming. A prototyp ...

lenticular galaxy A lenticular galaxy (denoted S0) is a type of galaxy intermediate between an elliptical (denoted E) and a spiral galaxy in galaxy morphological classification schemes. It contains a large-scale disc but does not have large-scale spiral arms. L ...

in the

constellation A constellation is an area on the celestial sphere in which a group of visible stars forms Asterism (astronomy), a perceived pattern or outline, typically representing an animal, mythological subject, or inanimate object. The origins of the e ...

Dorado Dorado () is a constellation in the southern sky. It was named in the late 16th century and is now one of the 88 modern constellations. Its name refers to the dolphinfish (''Coryphaena hippurus''), which is known as ''dorado'' in Spanish, altho ...

. It is the second brightest member of the

Dorado Group The Dorado Group is a loose concentration of galaxies containing both spirals and ellipticals. It is generally considered a 'galaxy group' but may approach the size of a 'galaxy cluster'. It lies primarily in the southern constellation Dorado a ...

of galaxies. British astronomer

John Herschel Sir John Frederick William Herschel, 1st Baronet (; 7 March 1792 – 11 May 1871) was an English polymath active as a mathematician, astronomer, chemist, inventor, experimental photographer who invented the blueprint and did botanical wor ...

discovered NGC 1553 on December 5, 1834 using an 18.7 inch

reflector Reflector may refer to: Science * Reflector, a device that causes reflection (for example, a mirror or a retroreflector) * Reflector (photography), used to control lighting contrast * Reflecting telescope * Reflector (antenna), the part of an ant ...

Interacting galaxy

It forms a pair of

interacting galaxies Interacting galaxies (''colliding 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 ...

together with

elliptical Elliptical may mean: * having the shape of an ellipse, or more broadly, any oval shape ** in botany, having an elliptic leaf shape ** of aircraft wings, having an elliptical planform * characterised by ellipsis (the omission of words), or by conc ...

NGC 1549 which lies 11′.8 away from it in the sky. Their interaction appears to be in the early stage and can be seen in optical wavelengths by faint but distinct irregular shells of emission and a curious jet on the northwest side. Together, these two galaxies comprise the center of the Dorado group.

Characteristics

NGC 1553 is an early type galaxy with a luminosity of 4 ''L''_⊙. It has been detected in H I but has an H I mass to B-band luminosity ratio (''M''_HI/''L''_B) of less than 0.01. NGC 1553's

ultraviolet Ultraviolet (UV) is a form of electromagnetic radiation with wavelength from 10 nanometer, nm (with a corresponding frequency around 30 Hertz, PHz) to 400 nm (750 Hertz, THz), shorter than that of visible light, but longer than ...

spectrum shows weak flux under the main-sequence turn off at around 2,400 A°. This is characteristic of old intermediate populations of

quiescent Quiescence (/kwiˈɛsəns/) is a state of quietness or inactivity. It may refer to: * Quiescence search, in game tree searching (adversarial search) in artificial intelligence, a quiescent state is one in which a game is considered stable and unl ...

lenticular galaxies. NGC 1553 has an especially well developed lens (~36″) component of nearly constant surface brightness that is found between the bulge and the exponential disk. Its lens is similar to what is found in NGC 3945 and its inner parts are very hot. NGC 1553 has associated with itself cool gas and dust. It can also be seen in

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 ...

and is a weak radio source.

Hubble 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 ...

observations in 2000 revealed an inner torus-like

dust lane A dust lane consists of a relatively dense, obscuring clouds of interstellar dust, observed as a dark swath against the background of a brighter object(s), especially a galaxy. These dust lanes can usually be seen in spiral galaxies, such as th ...

about 3″ across at the galaxy's center. Chandra X-ray imaging of NGC 1553 show diffuse hot gas making up 70% of the emissions, dotted with many point-like sources (

low-mass X-ray binaries X-ray binaries are a class of binary stars that are luminous in X-rays. The X-rays are produced by matter falling from one component, called the ''donor'' (usually a relatively normal star), to the other component, called the ''accretor'', which ...

) making up the rest. Similarly to

NGC 4697 NGC 4697 (also known as Caldwell 52) is an elliptical galaxy some 40 to 50 million light-years away in the constellation Virgo (constellation), Virgo. It is a member of the NGC 4697 Group, a group of galaxies also containing NGC 4731 and several ...

and

Messier 60 Messier 60 or M60, also known as NGC 4649, is an elliptical galaxy approximately 57 million light-years away in the equatorial constellation of Virgo. Together with NGC 4647, it forms a pair known as Arp 116. Messier 60 and nearby elliptic ...

, these bright spots are due to

binary star system A binary star is a system of two stars that are gravitationally bound to and in orbit around each other. Binary stars in the night sky that are seen as a single object to the naked eye are often resolved using a telescope as separate stars, in wh ...

s of

black hole A black hole is a region of spacetime where gravitation, gravity is so strong that nothing, including light or other Electromagnetic radiation, electromagnetic waves, has enough energy to escape it. The theory of general relativity predicts t ...

s and

neutron star A neutron star is the collapsed core of a massive supergiant star, which had a total mass of between 10 and 25 solar masses, possibly more if the star was especially metal-rich. Except for black holes and some hypothetical objects (e.g. white ...

s most of which are located in globular clusters and reflect this old galaxy's very active past. In these systems, material pulled off a regular star is heated and gives off X-rays as it falls toward the accompanying black hole or neutron star. The brightest of the point sources is coincident with the galaxy's optical nucleus. Its luminosity and spectrum suggest its being an obscured central

active galactic nucleus An active galactic nucleus (AGN) is a compact region at the center of a galaxy that has a much-higher-than-normal luminosity over at least some portion of the electromagnetic spectrum with characteristics indicating that the luminosity is not pr ...

(AGN). This source is visible in the center of the X-ray image of NGC 1553 shown above.

Globular clusters

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 have been resolved in the galaxy by the Hubble Space Telescope. There are an estimated 600 globulars in NGC 1553. Like

Messier 87 Messier 87 (also known as Virgo A or NGC 4486, generally abbreviated to M87) is a supergiant elliptical galaxy with several trillion stars in the constellation Virgo. One of the largest and most massive galaxies in the local uni ...

, there is a central deficit of globulars with respect to the underlying luminosity.

Spiral feature

NGC 1553 has a roughly symmetrical X-ray spiral feature (not detected in visible light) with a possible 10″ inner bar in the diffuse emission near the center of the galaxy. This feature is probably due to adiabatic or shock compression of ambient gas perhaps due to interaction with the radio source.

Hα H-alpha (Hα) is a specific deep-red visible spectral line in the Balmer series with a wavelength of 656.28 nm in air and 656.46 nm in vacuum; it occurs when a hydrogen electron falls from its third to second lowest energy level. H-alpha ...

emission also has spiral structure which is surprisingly similar to the X-ray spiral.

References

External links

Digital Sky Survey (DSS) visible light image of NGC 1553.
* {{DEFAULTSORT:NGC 1553 Lenticular galaxies Interacting galaxies Dorado Dorado Group

1553 Year 1553 ( MDLIII) was a common year starting on Sunday (link will display the full calendar) of the Julian calendar. Events January–June * May – The first Royal Charter is granted to St Albans, in England. * June – The ...

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