NGC 4945

Coordinates: Sky map 13h 05m 27.5s, −49° 28′ 06″

NGC 4945 is a barred spiral galaxy in the constellation Centaurus, visible near the star Xi Centauri.[3] The galaxy was discovered by James Dunlop in 1826 and is thought to be similar to the Milky Way Galaxy, although X-ray observations show that NGC 4945 has an unusual energetic Seyfert 2 nucleus that might house a supermassive black hole.[4] This object has an estimated mass of 1.4+1.4
−0.7
×106 M
.[5]

NGC 4945
Spiral Galaxy NGC 4945
Observation data (J2000 epoch)
ConstellationCentaurus
Right ascension 13h 05m 27.5s[1]
Declination−49° 28′ 06″[1]
Redshift563 ± 3 km/s[1]
Distance11.7 Mly (3.6 Mpc)[2]
Apparent magnitude (V)9.3[1]
Characteristics
TypeSB(s)cd[1]
Apparent size (V)20′.0 × 3′.8[1]
Other designations
PGC 45279,[1] Caldwell 83

Galaxy group

NGC 4945 one of the brightest galaxies of the Centaurus A/M83 Group, a large, nearby group of galaxies. The galaxy is the second brightest galaxy in the subgroup centered on Centaurus A.[2][6]

In popular culture

NGC 4945 is the title of a song by Brett Domino on the album "Funk".

References

  1. ^ a b c d e f g "NASA/IPAC Extragalactic Database". Results for NGC 4945. Retrieved 2006-11-25.
  2. ^ a b I. D. Karachentsev; M. E. Sharina; A. E. Dolphin; E. K. Grebel; et al. (2002). "New distances to galaxies in the Centaurus A group". Astronomy and Astrophysics. 385 (1): 21–31. Bibcode:2002A&A...385...21K. doi:10.1051/0004-6361:20020042.
  3. ^ http://www.docdb.net/show_object.php?id=ngc_4945, NGC 4945 : DOCdb :Deep Sky Observer's Companion – the online database
  4. ^ "Milky Way's Not-So-Distant Cousin Likely Harbors Supermassive Black Hole". Science Daily.
  5. ^ Graham, Alister W. (November 2008), "Populating the Galaxy Velocity Dispersion - Supermassive Black Hole Mass Diagram: A Catalogue of (Mbh, σ) Values", Publications of the Astronomical Society of Australia, 25 (4): 167–175, arXiv:0807.2549, Bibcode:2008PASA...25..167G, doi:10.1071/AS08013.
  6. ^ I. D. Karachentsev (2005). "The Local Group and Other Neighboring Galaxy Groups". Astronomical Journal. 129 (1): 178–188. arXiv:astro-ph/0410065. Bibcode:2005AJ....129..178K. doi:10.1086/426368.

External links

Brett Domino

Brett Domino is the alter-ego of musician and comedian Rob J. Madin. As Brett Domino, he is a YouTube musician and internet celebrity from Leeds, West Yorkshire, England, UK. He is best known for his YouTube videos, in which he plays covers, medleys and original songs on various musical instruments, most notably the keytar and Stylophone. His band The Brett Domino Trio currently consists of only two members, Domino and "Steven Peavis" (Ste Anderson), and during comic relief 2017, Russell Brand became an honorable member for the night making it an actual trio, having only actually been a three-piece for around a year. "Mitch Hutchinson" (Michael Denny) left the band in 2009 to become a forklift truck driver; he later returned to celebrate the band's fifth anniversary and appear on the finale of Brett Domino's Weekly YouTube Thing.

The Brett Domino Trio were featured a number of times as part of BBC Radio 1's The Chris Moyles Show in 2008, and in 2009 the band appeared on ITV's Britain's Got Talent, performing live as the house band on two episodes of ITV2's sister show, Britain's Got More Talent.Domino's YouTube videos have received over 28,000,000 views, and have been promoted by the likes of Justin Timberlake, Lady Gaga, and Ellie Goulding.

On 22 November 2010, Domino released a song called "Gillian McKeith", a humorous take on the celebrity during her time in the 10th series of the ITV show I'm a Celebrity... Get Me Out of Here!. The YouTube video gained over 1 million views in a week and entered the UK Singles Chart at number 29 on 28 November 2010.

In 2011, Madin introduced a YouTube character named "C-Bomb" — a self-proclaimed dubstep super-producer and 'cousin' of Domino's. On 14 June 2012, BBC Comedy uploaded a specially commissioned C-Bomb music video entitled "Bowl Date" to itswebsite and YouTube channel, followed by a further music video "Mutha Nature" on 4 October 2012.

Domino appeared on Blue Peter, the BBC children's programme, on 1 March 2012, performing a comedy song detailing a shortlist for the best children's book of the last ten years. Domino continued to produce regular musical segments for the show between 2012 and 2014.

In October–November 2012, Madin was commissioned to write a number of Domino songs for the BBC programme Young Apprentice. He wrote five songs that were released weekly via the BBC's YouTube channel.

On 1 July 2013, a 20-minute sitcom pilot entitled C-Bomb was launched on BBC iPlayer and subsequently broadcast on BBC Three. The pilot was written by Madin with Jason Cook and Daniel Peak.

Domino's "How To Make A Hit Pop Song" video was nominated for the Best Internet Comedy Short award at the 2014 British Comedy Awards. Madin and Anderson attended the event as themselves.

Between 2015-16, Domino was a regular guest on ITV's Weekend with Aled Jones, presenting a musical segment, often involving the other guests on the show. On 16 August 2015 he performed a medley of Shaggy songs with Shaggy himself.

The Brett Domino Trio appeared in Dictionary Corner on 8 Out of 10 Cats Does Countdown in August 2016, January 2017 and January 2019.

C83

C83 may refer to:

Byron Airport, a public airport serving Contra Costa County, California, USA.

Corydoras loxozonus, a freshwater catfish.

Ruy Lopez chess openings ECO code

Diffuse non-Hodgkin's lymphoma ICD-10 code

HMS Southampton (C83), a 1934 British Royal Navy cruiser

Labour Standards (Non-Metropolitan Territories) Convention, 1947 code

Caldwell 83 (NGC 4945), a spiral galaxy in the constellation CentaurusC-83 may refer to :

C-83 Coupe, an aircraft

Caldwell catalogue

The Caldwell catalogue is an astronomical catalogue of 109 star clusters, nebulae, and galaxies for observation by amateur astronomers. The list was compiled by Patrick Moore as a complement to the Messier catalogue.While the Messier catalogue is used by amateur astronomers as a list of deep-sky objects for observation, Moore noted that Messier's list was not compiled for that purpose and excluded many of the sky's brightest deep-sky objects, such as the Hyades, the Double Cluster (NGC 869 and NGC 884), and the Sculptor Galaxy (NGC 253). The Messier catalogue was actually compiled as a list of known objects that might be confused with comets. Moore also observed that since Messier compiled his list from observations in Paris, it did not include bright deep-sky objects visible in the Southern Hemisphere, such as Omega Centauri, Centaurus A, the Jewel Box, and 47 Tucanae. Moore compiled a list of 109 objects to match the commonly accepted number of Messier objects (he excluded M110), and the list was published in Sky & Telescope in December 1995.Moore used his other surname – Caldwell – to name the list, since the initial of "Moore" is already used for the Messier catalogue. Entries in the catalogue are designated with a "C" and the catalogue number (1 to 109).

Unlike objects in the Messier catalogue, which are listed roughly in the order of discovery by Messier and his colleagues, the Caldwell catalogue is ordered by declination, with C1 being the most northerly and C109 being the most southerly, although two objects (NGC 4244 and the Hyades) are listed out of sequence. Other errors in the original list have since been corrected: it incorrectly identified the S Norma Cluster (NGC 6087) as NGC 6067 and incorrectly labelled the Lambda Centauri Cluster (IC 2944) as the Gamma Centauri Cluster.

Centaurus

Centaurus is a bright constellation in the southern sky. One of the largest constellations, Centaurus was included among the 48 constellations listed by the 2nd-century astronomer Ptolemy, and it remains one of the 88 modern constellations. In Greek mythology, Centaurus represents a centaur; a creature that is half human, half horse (another constellation named after a centaur is one from the zodiac: Sagittarius). Notable stars include Alpha Centauri, the nearest star system to the Solar System, its neighbour in the sky Beta Centauri, and V766 Centauri, one of the largest stars yet discovered. The constellation also contains Omega Centauri, the brightest globular cluster as visible from Earth and one of the largest known.

Centaurus A/M83 Group

The Centaurus A/M83 Group is a complex group of galaxies in the constellations Hydra, Centaurus, and Virgo. The group may be roughly divided into two subgroups. The Cen A Subgroup, at a distance of 11.9 Mly (3.66 Mpc), is centered on Centaurus A, a nearby radio galaxy. The M83 Subgroup, at a distance of 14.9 Mly (4.56 Mpc), is centered on the Messier 83 (M83), a face-on spiral galaxy.This group is sometimes identified as one group and sometimes identified as two groups. Hence, some references will refer to two objects named the Centaurus A Group and the M83 Group. However, the galaxies around Centaurus A and the galaxies around M83 are physically close to each other, and both subgroups appear not to be moving relative to each other.The Centaurus A/M83 Group is part of the Virgo Supercluster, the local supercluster of which the Local Group is an outlying member.

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.

List of nearest galaxies

This is a list of known galaxies within 3.59 megaparsecs (11.7 million light-years) of the Solar System, in ascending order of distance.

This encompasses all of the about 50 Local Group galaxies, and some that are members of neighboring galaxy groups, the M81 Group and the Centaurus A/M83 Group, and some that are currently not in any defined galaxy group.

The list aims to reflect current knowledge: not all galaxies within the 3.59 Mpc radius have been discovered. Nearby dwarf galaxies are still being discovered, and galaxies located behind the central plane of the Milky Way are extremely difficult to discern. It is possible for any galaxy to mask another located beyond it.

Intergalactic distance measurements are subject to large uncertainties. Figures listed are composites of many measurements, some of which may have had their individual error bars tightened to the point of no longer overlapping with each other.

List of spiral galaxies

A spiral galaxy is a type of galaxy characterized by a central bulge of old Population II stars surrounded by a rotating disc of younger Population I stars. A spiral galaxy maintains its spirals arms due to density wave theory.

Local Sheet

The Local Sheet in astronomy is a nearby extragalactic region of space where the Milky Way, the members of the Local Group and other galaxies share a similar peculiar velocity. This region lies within a radius of about 7 Mpc (23 Mly), 0.46 Mpc (1.5 Mly) thick, and galaxies beyond that distance show markedly different velocities. The Local Group has only a relatively small peculiar velocity of 66 km⋅s−1 with respect to the Local Sheet. Typical velocity dispersion of galaxies is only 40 km⋅s−1 in the radial direction. Nearly all nearby bright galaxies belong to the Local Sheet. The Local Sheet is part of the Local Volume and is in the Virgo Supercluster (Local Supercluster). The Local Sheet forms a wall of galaxies delineating one boundary of the Local Void.A significant component of the mean velocity of the galaxies in the Local Sheet appears as the result of the gravitational attraction of the Virgo Cluster of galaxies, resulting in a peculiar motion ~185 km⋅s−1 toward the cluster. A second component is directed away from the center of the Local Void; an expanding region of space spanning an estimated 45 Mpc (150 Mly) that is only sparsely populated with galaxies. This component has a velocity of 259 km⋅s−1. The Local Sheet is inclined 8° from the Local Supercluster (Virgo Supercluster).The so-called Council of Giants is a ring of twelve large galaxies surrounding the Local Group in the Local Sheet, with a radius of 3.75 Mpc (12.2 Mly). Ten of these are spirals, while the remaining two are ellipticals. The two ellipticals (Maffei 1 and Centaurus A) lie on opposite sides of the Local Group, and their formation may have prompted the development of the Local Group. The Local Sheet's own development outlines a concentration of dark matter in a filament.

* The mass is given as the logarithm of the mass in solar masses.

Megamaser

A megamaser is a type of astrophysical maser, which is a naturally occurring source of stimulated spectral line emission. Megamasers are distinguished from astrophysical masers by their large isotropic luminosity. Megamasers have typical luminosities of 103 solar luminosities (L☉), which is 100 million times brighter than masers in the Milky Way, hence the prefix mega. Likewise, the term kilomaser is used to describe masers outside the Milky Way that have luminosities of order L☉, or thousands of times stronger than the average maser in the Milky Way, gigamaser is used to describe masers billions of times stronger than the average maser in the Milky Way, and extragalactic maser encompasses all masers found outside the Milky Way. Most known extragalactic masers are megamasers, and the majority of megamasers are hydroxyl (OH) megamasers, meaning the spectral line being amplified is one due to a transition in the hydroxyl molecule. There are known megamasers for three other molecules: water (H2O), formaldehyde (H2CO), and methine (CH).

Water megamasers were the first type of megamaser discovered. The first water megamaser was found in 1979 in NGC 4945, a galaxy in the nearby Centaurus A/M83 Group. The first hydroxyl megamaser was found in 1982 in Arp 220, which is the nearest ultraluminous infrared galaxy to the Milky Way. All subsequent OH megamasers that have been discovered are also in luminous infrared galaxies, and there are a small number of OH kilomasers hosted in galaxies with lower infrared luminosities. Most luminous infrared galaxies have recently merged or interacted with another galaxy, and are undergoing a burst of star formation. Many of the characteristics of the emission in hydroxyl megamasers are distinct from that of hydroxyl masers within the Milky Way, including the amplification of background radiation and the ratio of hydroxyl lines at different frequencies. The population inversion in hydroxyl molecules is produced by far infrared radiation that results from absorption and re-emission of light from forming stars by surrounding interstellar dust. Zeeman splitting of hydroxyl megamaser lines may be used to measure magnetic fields in the masing regions, and this application represents the first detection of Zeeman splitting in a galaxy other than the Milky Way.

Water megamasers and kilomasers are found primarily associated with active galactic nuclei, while galactic and weaker extragalactic water masers are found in star forming regions. Despite different environments, the circumstances that produce extragalactic water masers do not seem to be very different from those that produce galactic water masers. Observations of water megamasers have been used to make accurate measurements of distances to galaxies in order to provide constraints on the Hubble constant.

NGC 1386

NGC 1386 is a spiral galaxy located in the constellation Eridanus. It is located at a distance of circa 53 million light years from Earth, which, given its apparent dimensions, means that NGC 1386 is about 50,000 light years across. It is a Seyfert galaxy.

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.

Xi1 Centauri

Xi1 Centauri, Latinized from ξ1 Centauri, is a solitary star in the southern constellation of Centaurus. It is visible to the naked eye with an apparent visual magnitude of +4.83. With an annual parallax shift of 14.79 mas, it is located around 221 light years from the Sun. At that distance, the apparent visual magnitude of the star is diminished by an interstellar extinction factor of 0.10 due to intervening dust. Just 17 arc minutes to the east of Xi1 Centauri lies the galaxy NGC 4945.This is an A-type main sequence star with a stellar classification of A0 V. It is about 125 million years old with a relatively high rate of spin, having a projected rotational velocity of 185 km/s. The star has an estimated 2.4 times the mass of the Sun and about 2.7 times the Sun's radius. It is radiating 43 times the solar luminosity from its outer atmosphere at an effective temperature of 10,462 K.

List
See also

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