NGC 1566, sometimes known as the Spanish Dancer, is an intermediate spiral galaxy in the constellation Dorado. It is the dominant and brightest member of the Dorado Group, being among the brightest Seyfert galaxies in the sky. Absolute luminosity is 3.7×1010 L☉, and is calculated to contain 1.4×1010 M☉ of H I.
A close-up image of NGC 1566 taken by the Hubble’s Wide Field Camera 3.
|Observation data (J2000 epoch)|
|Right ascension||4h 20m .4s|
|Declination||−54° 56′ 16″|
|Helio radial velocity||1504 ± 2 km/s|
|Distance||38.4 ± 18.6 Mly|
(11.8 ± 5.7 Mpc)
|Apparent magnitude (V)||10.3|
|Apparent size (V)||8′.3 × 6′.6|
δ Doradus (often Latinised to Delta Doradus, abbreviated to δ Dor or delta Dor) is a star in the southern constellation of Dorado. Based upon an annual parallax shift of 21.80 mas as seen from Earth, it is located around 150 light years from the Sun. The star is visible to the naked eye with an apparent visual magnitude of +4.34.This is an A-type main sequence star with a stellar classification of A7 V. The star is spinning rapidly with a projected rotational velocity of 172 km/s. This is giving the star an oblate shape with an equatorial bulge that is 12% larger than the polar radius. Although A-type stars are not expected to harbor a magnetic dynamo needed to power X-ray emission, an X-ray flux of 3.6×1027 erg/s has been detected at these coordinates. This may indicate that the star has an unseen companion. δ Doradus displays an infrared excess suggesting it may be a Vega-like star with an orbiting debris disk.Currently this star is the Moon's south pole star, which occurs once every 18.6 years. The pole star status changes periodically, because of the precession of the Moon's rotational axis. When δ Doradus is the pole star, it is better aligned than Earth's Polaris (α Ursae Minoris), but much fainter. It is also the south pole star of Jupiter.Dorado
Dorado (English pronunciation: ) 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 Portuguese, although it has also been depicted as a swordfish. Dorado contains most of the Large Magellanic Cloud, the remainder being in the constellation Mensa. The South Ecliptic pole also lies within this constellation.
Even though the name Dorado is not Latin but Portuguese, astronomers give it the Latin genitive form Doradus when naming its stars; it is treated (like the adjacent asterism Argo Navis) as a feminine proper name of Greek origin ending in -ō (like Io or Callisto or Argo), which have a genitive ending -ūs.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 and is one of the richest galaxy groups of the Southern Hemisphere. Gérard de Vaucouleurs was the first to identify it in 1975 as a large complex nebulae II in the Dorado region, designating it as G16.Epsilon Doradus
Epsilon Doradus (ε Dor) is a solitary star located in the southern constellation of Dorado. It is visible to the naked eye with an apparent visual magnitude of 5.11. Based upon an annual parallax shift of 5.68 mas as measured from Earth, it is located roughly 570 light years from the Sun. At that distance, the visual magnitude of the star is diminished by an extinction factor of 0.09 due to interstellar dust.This is a B-type main sequence star with a stellar classification of B6 V. It is a slowly pulsating B-type star with a mean longitudinal magnetic field strength of −64±26 G. With 4.31 times the mass of the Sun and 3.8 times the Sun's radius, it is about 85% of the way through its main sequence lifetime. Epsilon Doradus radiates 556 times the solar luminosity from its photosphere at an effective temperature of 13,212 K.List of black holes
This is a list of black holes (and stars considered probable candidates) organized by size (including black holes of undetermined mass); some items in this list are galaxies or star clusters that are believed to be organized around a black hole. Messier and New General Catalogue designations are given where possible.Messier 77
Messier 77 or M77, also known as NGC 1068, is a barred spiral galaxy about 47 million light-years away in the constellation Cetus. Messier 77 was discovered by Pierre Méchain in 1780, who originally described it as a nebula. Méchain then communicated his discovery to Charles Messier, who subsequently listed the object in his catalog. Both Messier and William Herschel described this galaxy as a star cluster. Today, however, the object is known to be a galaxy.
The morphological classification of NGC 1068 in the De Vaucouleurs system is (R)SA(rs)b, where the '(R)' indicates an outer ring-like structure, 'SA' denotes a non-barred spiral, '(rs)' means a transitional inner ring/spiral structure, and 'b' says the spiral arms are moderately wound. Ann et al. (2015) gave it a class of SAa, suggesting a non-barred spiral galaxy with tightly wound arms. However, infrared images of the inner part of the galaxy reveal a prominent bar feature not seen in visual light, and for this reason it is now considered a barred spiral.Messier 77 is an active galaxy with an Active Galactic Nucleus (AGN), which is obscured from view by astronomical dust at visible wavelengths. The diameter of the molecular disk and hot plasma associated with the obscuring material was first measured at radio wavelengths by the VLBA and VLA. The hot dust around the nucleus was subsequently measured in the mid-infrared by the MIDI instrument at the VLTI. It is the brightest and one of the closest and best-studied type 2 Seyfert galaxies, forming a prototype of this class.X-ray source 1H 0244+001 in Cetus has been identified as Messier 77. Only one supernova has been detected in Messier 77. The supernova, named SN 2018 ivc, was discovered on 24 November 2018 by the DLT40 Survey. It is a type II supernova, and at discovery it was 15th magnitude and brightening.NGC 1549
NGC 1549 is an elliptical galaxy located in the constellation Dorado. It is located at a distance of circa 50 million light years from Earth, which, given its apparent dimensions, means that NGC 1549 is about 75,000 light years across. NGC 1549 was discovered by John Herschel on 6 December 1835 and may have been observed by James Dunlop in 1826. It is a member of the Dorado Group.
In the centre of NGC 1549 is expected to lie a supermassive black hole, whose mass is estimated to be between 390 and 810 million (108.76+0.15−0.17) M☉ based on the Sérsic index of the galaxy. No polycyclic aromatic hydrocarbons (PAHs) emission, an indicator for the presence of interstellar dust, was detected by the Infrared Spectrograph onboard Spitzer Space Telescope. NGC 1549 has been found to emit X-rays, with its total flux excceding 2×1040 ergs s–1 for the 0.3–5 keV band. A total number of 150 globular clusters are estimated to exist in NGC 1549, a number low compared to similar size galaxies. The outer isophotes of the galaxy appear twisted and feature faint shells.NGC 1549 forms an interacting pair with the lenticular galaxy NGC 1553, which lies 12 arcminutes to the south. It is the largest elliptical galaxy in a moderate size galaxy group known as the Dorado Group.NGC 1553
NGC 1553 is a prototypical lenticular galaxy in the constellation Dorado. It is the second brightest member of the Dorado Group of galaxies. British astronomer John Herschel discovered NGC 1553 on December 5, 1834 using an 18.7 inch reflector.Nu Doradus
Nu Doradus, Latinized from ν Doradus, is the Bayer designation for a single, blue-white hued star in the southern constellation of Dorado. It is visible to the naked eye with an apparent visual magnitude of +5.06. Based upon an annual parallax shift of 10.88 mas as seen from Earth, it is located about 300 light years from the Sun. At that distance, the visual magnitude is diminished by an extinction of 0.07 due to interstellar dust. It is moving further from the Sun with a heliocentric radial velocity of +17.5 km/s.This is an ordinary B-type main-sequence star, as indicated by its stellar classification of B8 V. It is an estimated 118 million years old and is spinning with a projected rotational velocity of 98 km/s. The star has 2.7 times the mass of the Sun and about 3.2 times the Sun's radius. It is radiating 107 times the Sun's luminosity from its photoshere at an effective temperature of 11,381 K. No infrared excess has been detected.Seyfert galaxy
Seyfert galaxies are one of the two largest groups of active galaxies, along with quasars. They have quasar-like nuclei (very luminous, distant and bright sources of electromagnetic radiation) with very high surface brightnesses whose spectra reveal strong, high-ionisation emission lines, but unlike quasars, their host galaxies are clearly detectable.Seyfert galaxies account for about 10% of all galaxies and are some of the most intensely studied objects in astronomy, as they are thought to be powered by the same phenomena that occur in quasars, although they are closer and less luminous than quasars. These galaxies have supermassive black holes at their centers which are surrounded by accretion discs of in-falling material. The accretion discs are believed to be the source of the observed ultraviolet radiation. Ultraviolet emission and absorption lines provide the best diagnostics for the composition of the surrounding material.Seen in visible light, most Seyfert galaxies look like normal spiral galaxies, but when studied under other wavelengths, it becomes clear that the luminosity of their cores is of comparable intensity to the luminosity of whole galaxies the size of the Milky Way.Seyfert galaxies are named after Carl Seyfert, who first described this class in 1943.Theta Doradus
Theta Doradus (Theta Dor, θ Doradus, θ Dor) is a solitary star in the southern constellation of Dorado. Based upon an annual parallax shift of 6.64 mas as seen from Earth, it is located around 490 light years from the Sun. With an apparent visual magnitude of +4.82, the star is bright enough to be faintly visible to the naked eye.
This is an evolved orange-hued K-type giant star with a stellar classification of K2/3 III CNIb/II, where the suffix indicates it is a chemically peculiar star with a strong CN band. With an age of around 1.17 billion years, it has an estimated 2.23 times the mass of the Sun and has expanded to about 16 times the Sun's radius. It is radiating 426.6 times the solar luminosity from its photosphere at an effective temperature of 4,320 K.