NGC 5643 is an

intermediate spiral galaxy An intermediate spiral galaxy is a galaxy that is in between the classifications of a barred spiral galaxy and an unbarred spiral galaxy. It is designated as SAB in the galaxy morphological classification system devised by Gerard de Vaucouleur ...

in the constellation

Lupus Lupus, formally called systemic lupus erythematosus (SLE), is an autoimmune disease in which the body's immune system mistakenly attacks healthy tissue in many parts of the body. Symptoms vary among people and may be mild to severe. Common ...

. Based on the

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 ...

distance indicator, it is located at a distance of about 40 million light-years (12.5 megaparsecs). NGC 5643 has an

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 ...

and is a type II

Seyfert galaxy Seyfert galaxies are one of the two largest groups of active galaxies, along with quasar host galaxies. They have quasar-like nuclei (very luminous sources of electromagnetic radiation that are outside of our own galaxy) with very high surface ...

Observation history

The galaxy was first discovered by

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 May 10, 1826, with his 9-inch reflector telescope, who described it as exceedingly faint. The galaxy was also spotted by

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 and experimental photographer who invented the blueprint and did botanical work. ...

and added to the ''

General Catalogue of Nebulae and Clusters A general officer is an officer of high rank in the armies, and in some nations' air and space forces, marines or naval infantry. In some usages, the term "general officer" refers to a rank above colonel."general, adj. and n.". OED Online. Mar ...

'' as number 3572. The galaxy is located only 15 degrees from the galactic plane.

Structure

NGC 5643 is a

grand design spiral galaxy A grand design spiral galaxy is a spiral galaxy with prominent and well-defined continuous spiral arms, as opposed to multi-arm, patchy and flocculent spirals which have subtler structural features. The spiral arms of a grand design galaxy exten ...

, with two well-defined, symmetric arms. In the circumnuclear region are other dust spirals, but the two main dust arms are wider. The galaxy is seen nearly face on, at an inclination of ~ 27°.

Active galactic nucleus

The galaxy has a low-luminosity

of Seyfert 2 type and is also a

luminous infrared galaxy Luminous infrared galaxies or LIRGs are galaxies with luminosities, the measurement of brightness, above . They are also referred to as submillimeter galaxies (SMGs) through their normal method of detection. LIRGs are more abundant than starburst ...

. The galaxy has a double sided diffuse radiojet. The galaxy exhibits an extended emission line region elongated in a direction close to the radio position angle of 87°±3°. Chris Simpson et al. analysed images takes from the WFPC2 camera of the

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 ...

in IIIλ5007 and Hα and found emission extending eastward for at least 1.8 kpc and in the IIIHα map a well-defined V-shaped structure that they identified as the projection of a tridimensional ionisation cone, which shares the same axis with the radio emission. A dust lane perpendicular to this axis obstructs the nucleus from direct view. A disk of material was found when the data cubes of VLT were analysed. It is aligned with the nucleus and circles it and possibly provides gas to the active galactic nucleus. The mass of the

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 ...

has been estimated based on the galaxy stellar velocity dispersion to be 10^6.4 M⊙. It has been proposed that the gas outflow has led to star formation on two locations on the bar of the galaxy which lie at the location where the gas from the nucleus encounters the dense material of the bar. Via observations of the galaxy from the

XMM Newton ''XMM-Newton'', also known as the High Throughput X-ray Spectroscopy Mission and the X-ray Multi-Mirror Mission, is an X-ray space observatory launched by the European Space Agency in December 1999 on an Ariane 5 rocket. It is the second cornerst ...

telescope in 2009, the galaxy is found to have a Compton–thick active galactic nucleus. Also the galaxy emits soft X-rays, mainly from photoionized matter. The presence of the compton-thick column which obstructs the nucleus was confirmed from observations by

NuSTAR NuSTAR (Nuclear Spectroscopic Telescope Array, also named Explorer 93 and SMEX-11) is a NASA space-based X-ray telescope that uses a conical approximation to a Wolter telescope to focus high energy X-rays from astrophysical sources, especial ...

Ultraluminous X-ray source

In 2004, Guainazzi et al. detected in the images from XMM-Newton an

ultraluminous X-ray source In astronomy and astrophysics, an ultraluminous X-ray source (ULX) is less luminous than an active galactic nucleus but more consistently luminous than any known stellar process (over 1039 erg/s, or 1032 watts), assuming that it radiates isotropi ...

, named NGC 5643 ULX1, located within 0.8 arcminutes from the nucleus. The source outshone the nucleus in X-rays and if it is located within NGC 5643 its luminosity is over 10⁴⁰ erg/s. Its luminosity is variable. The X-rays could be produced either by an advection dominated disc or a Comptonising corona and the X-ray source is considered to be a

black hole A black hole is a massive, compact astronomical object so dense that its gravity prevents anything from escaping, even light. Albert Einstein's theory of general relativity predicts that a sufficiently compact mass will form a black hole. Th ...

of stellar origin of approximately 30

solar mass The solar mass () is a frequently used unit of mass in astronomy, equal to approximately . It is approximately equal to the mass of the Sun. It is often used to indicate the masses of other stars, as well as stellar clusters, nebulae, galaxie ...

es.

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 recorded within the galaxy: * SN 2013aa ( typeIa, mag. 11.9) was discovered by Stuart Parker from

New Zealand New Zealand () is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and List of islands of New Zealand, over 600 smaller islands. It is the List of isla ...

on 13 February 2013, as part of the

Backyard Observatory Supernova Search The Backyard Observatory Supernova Search (BOSS) is conducted by astronomers from Australia and New Zealand since mid 2008 to search for new supernova A supernova (: supernovae or supernovas) is a powerful and luminous explosion of a star. A ...

. It was classified as a type Ia a few days before maximum brightness. It got as bright as magnitude 11.3, making it the brightest supernova of the year 2013. * SN 2017cbv (typeIa, mag. 16.0451) was discovered by the ''Distance Less Than 40 Mpc Survey'' (DLT40) on 10 March 2017. It increased in magnitude from 15.8 to 14.8 within the next day. It got as bright as magnitude 11.5, making it the brightest supernova of the year 2017.

Nearby galaxies

NGC 5643 has a satellite dwarf galaxy, ESO 273-014. NGC 5643 is the largest member of a small galaxy group that also includes NGC 5530.

References

External links

{{Lupus (constellation) Barred spiral galaxies Seyfert galaxies Lupus (constellation) 5643 51969 272-G016 -07-30-003 Galaxies discovered in 1826 Astronomical objects discovered in 1826 Discoveries by James Dunlop