NGC 1566, sometimes known as the Spanish Dancer, 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 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 ...

, positioned about 3.5° to the south of the star

Gamma Doradus Gamma Doradus, Latinized from γ Doradus, is the third-brightest star in the southern constellation of Dorado. It is faintly visible to the naked eye with an apparent visual magnitude of approximately 4.25, and is a variable st ...

. It was discovered on May 28, 1826 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 ...

. At 10th

magnitude Magnitude may refer to: Mathematics *Euclidean vector, a quantity defined by both its magnitude and its direction *Magnitude (mathematics), the relative size of an object *Norm (mathematics), a term for the size or length of a vector *Order of ...

, it requires a telescope to view. The distance to this galaxy remains elusive, with measurements ranging from up to . This galaxy forms a member of the NGC 1566 subgroup of the

Dorado Group The Dorado Group is a loose Galaxy groups and clusters, concentration of galaxies containing both spiral galaxy, spirals and elliptical galaxy, ellipticals. It is generally considered a 'galaxy group' but may approach the size of a 'galaxy clust ...

, of which it is dominant and brightest member (although Kilborn and colleagues (2005) listed it as second brightest member of the NGC 1566 group after NGC 1553). The X-ray emission from the group is dominated by the hot gas halo of this galaxy, which extends out to before merging with the background radiation. The galaxy appears to be interacting with smaller members of its subgroup. Radio emissions suggest the disk is asymmetrical and the neutral hydrogen gas shows a mild warp. The morphological classification of NGC 1566 is SAB(rs)bc, which indicates a spiral galaxy with a weak bar structure around the nucleus (SAB), an incomplete ring around the bar (rs), and showing wound

arms Arms or ARMS may refer to: *Arm or arms, the upper limbs of the body Arm, Arms, or ARMS may also refer to: People * Ida A. T. Arms (1856–1931), American missionary-educator, temperance leader Coat of arms or weapons *Armaments or weapons **Fi ...

(bc). The spiral arms are strong and symmetrical. The

galactic plane The galactic plane is the plane (geometry), plane on which the majority of a disk-shaped galaxy's mass lies. The directions perpendicular to the galactic plane point to the galactic poles. In actual usage, the terms ''galactic plane'' and ''galac ...

is inclined at an angle of to the

line of sight The line of sight, also known as visual axis or sightline (also sight line), is an imaginary line between a viewer/ observer/ spectator's eye(s) and a subject of interest, or their relative direction. The subject may be any definable object taken ...

to the

Earth Earth is the third planet from the Sun and the only astronomical object known to Planetary habitability, harbor life. This is enabled by Earth being an ocean world, the only one in the Solar System sustaining liquid surface water. Almost all ...

and the long axis is oriented along a

position angle In astronomy, position angle (usually abbreviated PA) is the convention for measuring angles on the sky. The International Astronomical Union defines it as the angle measured relative to the Celestial pole, north celestial pole (NCP), turning pos ...

of . The northwest side of the galaxy is more strongly obscured by dust, suggesting it is the near side. The mass ratio of neutral hydrogen gas to the mass of the stars is 0.29, which is on the high side for a galaxy of this mass. Absolute luminosity is , and is calculated to contain of H I. NGC 1566 is an

active galaxy 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 ...

with many features of a Seyfert type 1, although the exact type remains uncertain. It is one of the closest and brightest Seyfert galaxies. 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 ...

at the center is estimated at . The proximity of the galaxy, along with strong spiral arms and an active nucleus, have made it the subject of much scientific study in the astronomy community. It is the nearest known CL AGN galaxy.

Supernovae

Three

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 1566: * SN 2010el ( typeIax, mag. 16.8) was discovered by Berto Monard of South Africa on 19 June 2010. It was located west and south of the center of the galaxy. * SN 2021aefx ( Type Ia, mag 17.24) was discovered by the ''Distance Less Than 40 Mpc Survey'' (DLT40) on 11 November 2021. It reached magnitude 12, making it the brightest supernova of 2021. * ASASSN-14ha ( typeII, mag. 14.6) was discovered by All Sky Automated Survey for SuperNovae (ASAS-SN) on 10 September 2014.

Gallery

File:NGC1566 - Noirlab2208a.jpg, Spanish Dancer Galaxy Twirls into View from NSF’s NOIRLab in Chile Spanish Dancer Galaxy Twirls into View from NSF’s NOIRLab in Chile
Retrieved 30 January 2023. File:NGC 1566 (52523099436).png, Image of NGC 1566 taken by James Webb's

Mid-Infrared Instrument MIRI, or the Mid-Infrared Instrument, is an instrument on the James Webb Space Telescope. MIRI is a camera and a spectrograph that observes mid infrared, mid to long infrared radiation from 5 to 28 microns. It also has coronagraphs, especially ...

File:Sig05-013.jpg, Infrared Image of NGC 1566 taken by the

Spitzer Space Telescope The Spitzer Space Telescope, formerly the Space Infrared Telescope Facility (SIRTF), was an infrared space telescope launched in 2003, that was deactivated when operations ended on 30 January 2020. Spitzer was the third space telescope dedicate ...

References

External links

Spitzer Space Telescope page on NGC 1566
* Discovery image o
SN 2010el
(2010-06-19; The star to the left of the core of the galaxy is magnitude 12.3) * {{DEFAULTSORT:Ngc 1566 Intermediate spiral galaxies Seyfert galaxies Dorado Dorado Group

1566 __NOTOC__ Year 1566 (Roman numerals, MDLXVI) was a common year starting on Tuesday of the Julian calendar. Events January–March * January 7 – Cardinal Michele Ghislieri is 1565–1566 papal conclave, elected as the new Pope ...

14897 Discoveries_by_James_Dunlop Astronomical objects discovered in 1826