Centaurus A/M83 group | |
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![]() The Centaurus A galaxy is the largest and most massive galaxy in the group | |
Observation data (Epoch ) | |
Constellation(s) | Hydra, Centaurus, and Virgo [1] |
Right ascension | 13h 20m [2] |
Declination | −44° 58′ [2] |
Brightest member | Centaurus A [3] |
Number of galaxies | 44 [3] |
Other designations | |
NGC 5128 Group, [2] Centaurus A Group, [2] LGG 344 [2] | |
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. [3] 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. [3]
This group is sometimes identified as one group [4] [5] and sometimes identified as two groups. [6] 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. [3]
The Centaurus A/M83 Group is part of the Virgo Supercluster, the local supercluster of which the Local Group is an outlying member.
The brightest group members were frequently identified in early galaxy group identification surveys. [4] [5] However, many of the dwarf galaxies in the group were only identified in more intensive studies. One of the first of these identified 145 faint objects on optical images from the UK Schmidt Telescope and followed these up in hydrogen line emission with the Parkes Radio Telescope and in the hydrogen-alpha spectral line with the Siding Spring 2.3 m Telescope. This identified 20 dwarf galaxies as members of the group. [8] The HIPASS survey, which was a blind radio survey for hydrogen spectral line emission, found five uncatalogued galaxies in the group and also identified five previously-catalogued galaxies as members. [9] An additional dwarf galaxy was identified as a group member in the HIDEEP survey, which was a more intensive radio survey for hydrogen emission within a smaller region of the sky. [10] Several optical surveys later identified 20 more candidate objects to the group. [11] [12] [13] In 2007, the Cen A group membership of NGC 5011C was established. [14] While this galaxy is a well-known stellar system listed with a NGC number, its true identity remained hidden because of coordinate confusion and wrong redshifts in the literature. From 2015 to 2017 a full optical survey was conducted using the Dark Energy Camera, covering 550 square degrees in the sky and doubling the number of known dwarf galaxies in this group. [15] [16] Another deep but spatially limited survey around Centaurus A revealed numerous new dwarfs. [17]
The dwarf spheroidal galaxies of the Centaurus A group have been studied and have been found to have old, metal-poor stellar populations similar to those in the Local Group, and follow a similar metallicity–luminosity relation. One dwarf galaxy, KK98 203 (LEDA 166167), has an extended ring of Hα emission. [18]
The table below lists galaxies that have been identified as associated with the Centaurus A/M83 Group by I. D. Karachentsev and collaborators. [3] [13] Note that Karachentsev divides this group into two subgroups centered on Centaurus A and Messier 83.
Name | Type [2] | R.A. (J2000) [2] | Dec. (J2000) [2] | Redshift (km/s) [2] | Apparent Magnitude [2] |
---|---|---|---|---|---|
Cen 7 | Sph | 13h 11m 13.8s | −38° 53′ 56″ | 17.3 | |
Cen N | 13h 48m 09.1s | −47° 33′ 54″ | 17.5 | ||
Centaurus A (NGC 5128) | S0 pec | 13h 25m 27.6s | −43° 01′ 09″ | 547 ± 5 | 7.8 |
Centaurus A-dE1 | dSph | 13h 12m 45.2s | −41° 49′ 57″ | 19.3 | |
Centaurus A-dE3 | dE | 13h 46m 00.8s | −36° 19′ 44″ | 17.1 | |
HIPASS J1337-39 | Im | 13h 37m 25.3s | −39° 53′ 48″ | 492 ± 4 | 16.5 |
HIPASS J1348-37 | 13h 48m 47.0s | −37° 58′ 29″ | 581 ± 8 | 16.9 | |
HIPASS J1351-47 | 13h 51m 12.0s | −46° 58′ 12.9″ | 529 ± 6 | ||
KKs 51 | E/Sph | 12h 44m 21.5s | −42° 56′ 23″ | 16.7 | |
KKs 55 | Sph | 13h 22m 12.8s | −42° 43′ 41″ | 18.5 | |
KKs 57 | Sph | 13h 41m 38.1s | −42° 34′ 55″ | 18.1 | |
LEDA 166152 | dI | 13h 05m 02.1s | −40° 04′ 58″ | 617 ± 4 | 16.3 |
LEDA 166167 | dI/dSph | 13h 27m 27.8s | −45° 21′ 10″ | 18 | |
LEDA 166172 | dSph | 13h 43m 36.0s | −43° 46′ 11″ | 18.5 | |
LEDA 166175 | dSph | 13h 46m 16.8s | −45° 41′ 05″ | 19.2 | |
LEDA 166179 | dSph | 13h 48m 46.4s | −46° 59′ 46″ | 18 | |
NGC 4945 | SB(s)cd | 13h 05m 27.5s | −49° 28′ 06″ | 563 ± 3 | 9.3 |
NGC 5102 | SA0 | 13h 21m 57.6s | −36° 37′ 49″ | 468 ± 2 | 10.4 |
NGC 5206 | SB(r)0 | 13h 33m 44.0s | −48° 09′ 04″ | 571 ± 10 | 11.6 |
NGC 5237 | I0 | 13h 37m 39.0s | −42° 50′ 49″ | 361 ± 4 | 13.2 |
PGC 45104 | IABm | 13h 03m 33.6s | −46° 35′ 06″ | ||
PGC 45717 | I0 pec | 13h 10m 32.9s | −46° 59′ 27.3″ | 1853 ± 32 | 13.3 |
PGC 45916 | dE | 13h 13m 09.1s | −44° 53′ 24″ | 784 ± 31 | 14.1 |
PGC 46663 | IBm | 13h 21m 47.4s | −45° 03′ 42″ | 741 | 16.1 |
PGC 46680 | Im | 13h 22m 02.0s | −42° 32′ 07″ | 16.6 | |
PGC 47171 | IABm | 13h 27m 37.4s | −41° 28′ 50″ | 516 ± 3 | 12.9 |
PGC 48515 | dE | 13h 42m 05.6s | −45° 12′ 18″ | 17.6 | |
PGC 48738 | IB(s)m | 13h 45m 00.5s | −41° 51′ 40″ | 545 ± 2 | 14.0 |
PGC 49615 | dS0/Im | 13h 57m 01.4s | −35° 19′ 59″ | 561 ± 32 | 14.8 |
Name | Type [2] | R.A. (J2000) [2] | Dec. (J2000) [2] | Redshift (km/s) [2] | Apparent Magnitude [2] |
---|---|---|---|---|---|
AM 1321-304 | dIm | 13h 24m 36.2s | −30° 58′ 19″ | 487 ± 1 | 16.7 |
Centaurus A-dE2 | dE/Im | 13h 21m 32.4s | −31° 53′ 11″ | 17.6 | |
Centaurus A-dE4 | dSph | 13h 46m 40.4s | −29° 58′ 41″ | 19. | |
HIDEEP J1336-3321 | 13h 36m 56.1s | −33° 21′ 23″ | 591 | 17.3 | |
IC 4247 | S | 13h 26m 44.4s | −30° 21′ 45″ | 274 ± 65 | 14.4 |
IC 4316 | IBm pec | 13h 40m 18.4s | −28° 53′ 32″ | 674 ± 53 | 15.0 |
KK 208 | dI | 13h 36m 35.5s | −29° 34′ 17″ | 381 | 14.3 |
LEDA 166163 | dI | 13h 21m 08.2s | −31° 31′ 45″ | 571 ± 3 | 17.1 |
LEDA 166164 | dSph | 13h 22m 56.2s | −33° 34′ 22″ | 17.6 | |
M83 | SAB(s)c | 13h 37m 00.9s | −29° 51′ 57″ | 513 ± 2 | 8.2 |
NGC 5253 | Im pec | 13h 39m 55.9s | −31° 38′ 24″ | 407 ± 3 | 10.9 |
NGC 5264 | IB(s)m | 13h 41m 36.7s | −29° 54′ 47″ | 478 ± 3 | 12.6 |
PGC 47885 | 13h 35m 08.1s | −30° 07′ 03″ | 13848 | 15.8 | |
PGC 48111 | Im | 13h 37m 20.0s | −28° 02′ 42″ | 587 ± 3 | 15.0 |
UGCA 365 | Im | 13h 36m 31.1s | −29° 14′ 06″ | 573 ± 1 | 15.4 |
Additionally, ESO 219-010, PGC 39032, and PGC 51659 are listed as possibly being members of the Centaurus A Subgroup, and ESO 381-018, NGC 5408, and PGC 43048 are listed as possibly being members of the M83 Subgroup. [3] Although HIPASS J1337-39 is only listed as a possible member of the M83 Subgroup in the later list published by Karachentsev, [3] later analyses indicate that this galaxy is within the subgroup. [19] Saviane and Jerjen found that NGC 5011C has an optical redshift of 647 km/s and thus is a member of the Cen A group rather than of the distant Centaurus galaxy cluster as believed since 1983.
The Local Group is the galaxy group that includes the Milky Way. It has a total diameter of roughly 3 megaparsecs (10 million light-years; 9×1019 kilometres), and a total mass of the order of 2×1012 solar masses (4×1042 kg). It consists of two collections of galaxies in a "dumbbell" shape; the Milky Way and its satellites form one lobe, and the Andromeda Galaxy and its satellites constitute the other. The two collections are separated by about 800 kiloparsecs (3×10 6 ly; 2×1019 km) and are moving toward one another with a velocity of 123 km/s. The group itself is a part of the larger Virgo Supercluster, which may be a part of the Laniakea Supercluster. The exact number of galaxies in the Local Group is unknown as some are occluded by the Milky Way; however, at least 80 members are known, most of which are dwarf galaxies.
Messier 83 or M83, also known as the Southern Pinwheel Galaxy and NGC 5236, is a barred spiral galaxy approximately 15 million light-years away in the constellation borders of Hydra and Centaurus. Nicolas-Louis de Lacaille discovered M83 on 23 February 1752 at the Cape of Good Hope. Charles Messier added it to his catalogue of nebulous objects in March 1781. It is one of the closest and brightest barred spiral galaxies in the sky, and is visible with binoculars. Its nickname of the Southern Pinwheel derives from its resemblance to the Pinwheel Galaxy (M101).
Centaurus A is a galaxy in the constellation of Centaurus. It was discovered in 1826 by Scottish astronomer James Dunlop from his home in Parramatta, in New South Wales, Australia. There is considerable debate in the literature regarding the galaxy's fundamental properties such as its Hubble type and distance. NGC 5128 is one of the closest radio galaxies to Earth, so its active galactic nucleus has been extensively studied by professional astronomers. The galaxy is also the fifth-brightest in the sky, making it an ideal amateur astronomy target. It is only visible from the southern hemisphere and low northern latitudes.
NGC 404 is a field galaxy located about 10 million light years away in the constellation Andromeda. It was discovered by William Herschel in 1784, and is visible through small telescopes. NGC 404 lies just beyond the Local Group and does not appear gravitationally bound to it. It is located within 7 arc-minutes of second magnitude star Mirach, making it a difficult target to observe or photograph and granting it the nickname "Mirach's Ghost".
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NGC 185 is a dwarf spheroidal galaxy located 2.08 million light-years from Earth, appearing in the constellation Cassiopeia. It is a member of the Local Group, and is a satellite of the Andromeda Galaxy (M31). NGC 185 was discovered by William Herschel on November 30, 1787, and he cataloged it "H II.707". John Herschel observed the object again in 1833 when he cataloged it as "h 35", and then in 1864 when he cataloged it as "GC 90" within his General Catalogue of Nebulae and Clusters. NGC 185 was first photographed between 1898 and 1900 by James Edward Keeler with the Crossley Reflector of Lick Observatory. Unlike most dwarf elliptical galaxies, NGC 185 contains young stellar clusters, and star formation proceeded at a low rate until the recent past. NGC 185 has an active galactic nucleus (AGN) and is usually classified as a type 2 Seyfert galaxy, though its status as a Seyfert is questioned. It is possibly the closest Seyfert galaxy to Earth, and is the only known Seyfert in the Local Group.
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−0.7×1011 M☉.
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NGC 5253 is an irregular galaxy in the constellation Centaurus. It was discovered by William Herschel on 15 March 1787.
NGC 5408 is an irregular galaxy in the constellation Centaurus. It was discovered by John Herschel on June 5, 1834.
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NGC 5229 is an edge-on spiral galaxy located in the constellation Canes Venatici. It is a member of the M51 Group although in reality it is relatively isolated from other galaxies. The galaxy's disc is somewhat warped and appears to consist of a series of interconnected clusters of stars from our vantage point on Earth. It is approximately 7 kiloparsecs in diameter and is about 13.7 billion years old.
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