NGC 1672 is a

barred spiral galaxy A barred spiral galaxy is a spiral galaxy with a central bar-shaped structure composed of stars. Bars are found in about two thirds of all spiral galaxies in the local universe, and generally affect both the motions of stars and interstellar gas ...

located 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 first constellati ...

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 mahi-mahi (''Coryphaena hippurus''), which is known as ''dorado'' ("golden") in Sp ...

. It was discovered by Scottish astronomer

James Dunlop James Dunlop FRSE (31 October 1793 – 22 September 1848) was a Scottish astronomer, noted for his work in Australia. He was employed by Sir Thomas Brisbane to work as astronomer's assistant at his private observatory, once located at Param ...

on 5 November 1826. It was originally unclear whether it was a member of the Dorado Group, with some sources finding it to be a member and other sources rejecting its membership. However, recent

tip of the red-giant branch Tip of the red-giant branch (TRGB) is a primary distance indicator used in astronomy. It uses the luminosity of the brightest red-giant-branch stars in a galaxy as a standard candle to gauge the distance to that galaxy. It has been used in conjun ...

(TRGB) measurements indicate that NGC 1672 is located at the same distance as other members, suggesting it is indeed a member of the Dorado Group. NGC 1672 has a large bar which is estimated to measure around 20 kpc. It has very strong radio emissions emanating from its nucleus, bar, and the inner portion of the spiral arm region. The nucleus is Seyfert type II and is engulfed by a

starburst region A starburst region is a region of space that is undergoing a large amount of 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. Th ...

. The strongest polarized emissions come from the northeastern region which is upstream from its dust lanes. Magnetic field lines are at large angles with respect to the bar and turn smoothly to the center.

General structure

The center of the galaxy contains a high surface brightness bar, and four filament-like

spiral arm Spiral arms are a defining feature of spiral galaxies. They manifest as spiral-shaped regions of enhanced brightness within the galactic disc. Typically, spiral galaxies exhibit two or more spiral arms. The collective configuration of these arms i ...

s extend outward from the ends of this bar. The spiral arms are asymmetric; one of the arms in the northeast part of the disk is significantly brighter than its counterpart on the other side. The spiral arms also contain numerous

star formation Star formation is the process by which dense regions within molecular clouds in interstellar space—sometimes referred to as "stellar nurseries" or "star-forming regions"—Jeans instability, collapse and form stars. As a branch of astronomy, sta ...

regions, some of which may be as large as .

Nucleus

The classification of the nucleus of NGC 1672 is uncertain. Most galaxies may be classified by their spectra as having one of three different types of nuclei: *A nuclear H II region, a region which has a spectrum similar to that of

regions in the

Milky Way The Milky Way or Milky Way Galaxy is the galaxy that includes the Solar System, with the name describing the #Appearance, galaxy's appearance from Earth: a hazy band of light seen in the night sky formed from stars in other arms of the galax ...

and which therefore is associated with nuclear star formation activity. *A Seyfert nucleus, a type of

active galactic nucleus An active galactic nucleus (AGN) is a compact region at the center of a galaxy that emits a significant amount of energy across the electromagnetic spectrum, with characteristics indicating that this luminosity is not produced by the stars. Such e ...

(AGN) that may contain 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 ...

. *A

low-ionization nuclear emission-line region 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 ...

, a type of nuclear region with

spectral line A spectral line is a weaker or stronger region in an otherwise uniform and continuous spectrum. It may result from emission (electromagnetic radiation), emission or absorption (electromagnetic radiation), absorption of light in a narrow frequency ...

emission from weakly

ion An ion () is an atom or molecule with a net electrical charge. The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by convent ...

ized gas that could contain either a star formation region or a supermassive black hole. NGC 1672, however, is one of several nearby galaxies that does not fit into this classification scheme, as its spectrum appears intermediary between these three classes of objects. It may in fact contain both nuclear star formation regions and an AGN. In some wave bands (such as in

ultraviolet light Ultraviolet radiation, also known as simply UV, is electromagnetic radiation of wavelengths of 10–400 nanometers, shorter than that of visible light, but longer than X-rays. UV radiation is present in sunlight and constitutes about 10% of th ...

), the star formation regions are the primary source of emission.

Supernovae

Two

supernova A supernova (: supernovae or supernovas) is a powerful and luminous explosion of a star. A supernova occurs during the last stellar evolution, evolutionary stages of a massive star, or when a white dwarf is triggered into runaway nuclear fusion ...

e have been observed in NGC 1672: * SN 2017gax ( type Ib/c, mag. 14.1) was discovered by the ''Distance Less Than 40 Mpc Survey'' (DLT40) on 14 August 2017. * SN 2022aau ( type II, mag. 16.3) was discovered by DLT40 on 20 January 2022.

Gallery

NGC 1672 HST.jpg , A

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

image of the center region of NGC 1672 NGC 1672 GALEX WikiSky.jpg , A

GALEX Galaxy Evolution Explorer (GALEX or Explorer 83 or SMEX-7) was a NASA orbiting space telescope designed to observe the universe in ultraviolet wavelengths to measure the history of star formation in the universe. In addition to paving the way ...

ultraviolet Ultraviolet radiation, also known as simply UV, is electromagnetic radiation of wavelengths of 10–400 nanometers, shorter than that of visible light, but longer than X-rays. UV radiation is present in sunlight and constitutes about 10% of ...

image of NGC 1672 NGC 1672 (weic2403k).jpg , A

James Webb Space Telescope The James Webb Space Telescope (JWST) is a space telescope designed to conduct infrared astronomy. As the largest telescope in space, it is equipped with high-resolution and high-sensitivity instruments, allowing it to view objects too old, Lis ...

image of NGC 1672

References

External links

Hubblesite Newscenter: Pictures and description
{{DEFAULTSORT:NGC 1672 Barred spiral galaxies Seyfert galaxies LINER galaxies Dorado

1672 Events January–March * January 2 – After the government of England is unable to pay the nation's debts, Charles II of England, King Charles II decrees the Stop of the Exchequer, the suspension of payments for one year "up ...