NGC 3311 | |
---|---|
Observation data (J2000 epoch) | |
Constellation | Hydra |
Right ascension | 10h 36m 42.8s [1] |
Declination | −27° 31′ 42″ [1] |
Redshift | 0.012759 [1] |
Heliocentric radial velocity | 3825 km/s [1] |
Distance | 190 Mly (57 Mpc) [1] |
Group or cluster | Hydra Cluster |
Apparent magnitude (V) | 12.65 [1] |
Characteristics | |
Type | cD2, E+2 [1] |
Number of stars | more than 1 trillion [2] |
Size | ~230,000 ly (70 kpc) (estimated) [1] |
Apparent size (V) | 3.5 x 2.9 [1] |
Notable features | Massive globular cluster population |
Other designations | |
ESO 501-38, AM 1034-271, MCG -4-25-36, PGC 31478 [1] |
NGC 3311 is a super-giant [2] elliptical galaxy [3] (a type-cD galaxy) [4] [3] located about 190 million light-years away [5] in the constellation Hydra. [6] The galaxy was discovered by astronomer John Herschel on March 30, 1835. [7] [8] NGC 3311 is the brightest [9] [10] member of the Hydra Cluster [11] and forms a pair with NGC 3309 which along with NGC 3311, dominate the central region of the Hydra Cluster. [12]
NGC 3311 is surrounded by a rich and extensive globular cluster system [13] rivaling that of Messier 87 in the Virgo Cluster. [4]
The central region of NGC 3311 is obscured by a dust cloud [14] with an estimated diameter of 1,700 ly (0.53 kpc ). [15] It has an amorphous and complex structure and its small size and disturbed morphology suggests that the cloud originated from a merger event with another galaxy that occurred within the past 10 million years. Oddly though, there are no shells or isophote distortions in the outer regions of NGC 3311 that would have been the result of such a recent merger. Other scenarios for the origin of the dust cloud are by a cooling flow or by galactic wind failure.
The total estimated mass of the dust cloud is 4,600 solar masses (4.6×104 M☉). [14]
In NGC 3311, it has been detected that there is an excess blue population in the central region of the galaxy. The spectrum of the galaxy appears to resemble that of an H II region. This suggests that the excess blue population represents an ongoing formation of young bright stars. [16]
The outer halo of NGC 3311 appears to have formed from the accretion [17] and mergers of massive satellite galaxies in vicinity of the galaxy. [18] The halo is made up of intra-cluster stars with a dominant part of these stars coming from the outskirts of bright early-type galaxies and the rest originating from dwarf galaxies. [19] However, the build-up of its extended halo is still ongoing due to the infall of a group of 14 dwarf galaxies including the galaxies HCC 026 and HCC 007 that are currently being tidally disputed and adding their stars to the outer halo. [18] [17] [20] [9] In contrast, the inner galaxy formed from the mergers of gas-rich lumps reminiscent of the first phase of galaxy formation. [18]
The stars in the central region of NGC 3311 and in the halo are very old, with ages of over 10 Gyrs. However the stars in the central galaxy have a higher metallicity than the halo suggesting the stars in the stars in the central galaxy formed in a rapid but short period of star formation that occurred early on though a gas-rich dissipative collapse while the stars in halo formed in smaller accreted satellite galaxies with more extended star formation. [21]
NGC 3311 contains an off centered-envelope that was first detected by Arnaboldi et al. The off centered-envelope has a higher metallicity than the outer halo [20] and is located close to the infalling group of dwarf galaxies. [18] [20]
The envelope appears to have been offset from the center of NGC 3311 by a tidal interaction with the dark matter halos of the infalling group of dwarf galaxies or halo associated with NGC 3309. This tidal interaction would have also stripped gas and dust from the outer halo of NGC 3311. [18]
Around 60 intracluster planetary nebulae have been detected surrounding NGC 3311. [22]
NGC 3311 is host to a supermassive black hole with an estimated mass of 126 million solar masses (1.26 × 108 M☉). [23]
NGC 3311 appears to have a cored dark matter halo. [24]
NGC 3311 has a weak radio source with a total 6-cm flux density of 0.3 mJy. [13] [16]
Although NGC 3311 has a weak radio source, it is bright in X-rays. [25]
NGC 3311 has one of the largest globular cluster systems known in the local universe. With an estimated population of about 16,500 ± 2,000 globular clusters, NGC 3311's globular cluster system rivals that of Messier 87's, which has about 13,000 globular clusters. [4] NGC 3309, another nearby giant elliptical has an unusually low number of globular clusters. This suggests that NGC 3311 stripped part of NGC 3309's globular clusters, with some of its globular clusters becoming members of NGC 3311's system. [24]
NGC 3311's globular cluster system was initially detected in 1976 [26] and was found by Harris et al. in 1983 to contain a massive globular cluster system similar to Messier 87. [27]
An analysis by Secker et al. in 1995 using Washington photometry from the Cerro Tololo Inter-American Observatory concluded that NGC 3311 had the most metal-rich globular cluster system known, with a complete absence of populations of metal-poor and intermediate-metallicity globular clusters. [28] However, Brodie et al. and Wehner et al. determined that the globular cluster system shows a bimodal color distribution with equal numbers of metal-rich and metal-poor clusters. [29] [4]
A large population of about 50 ultra-compact dwarf galaxies (UDCs) [30] have been detected in the Hydra Cluster, [31] [30] with most of them being dynamically associated to NGC 3311. It appears that the ultra-compact dwarf galaxies, especially the brighter and more massive ones such as HUCD1 with a mass of 5×107 and a half-light radius of 83 ly (25.4 pc ) are the remnant nuclei of dwarf galaxies whose stellar envelopes were stripped off during an interaction with another galaxy or the cluster itself. [30]
Messier 59 or M59, also known as NGC 4621, is an elliptical galaxy in the equatorial constellation of Virgo. It is a member of the Virgo Cluster, with the nearest fellow member 8′ away and around 5 magnitudes fainter. The nearest cluster member of comparable brightness is the lenticular galaxy NGC 4638, which is around 17′ away. It and the angularly nearby elliptical galaxy Messier 60 were both discovered by Johann Gottfried Koehler in April 1779 when observing comet seeming close by. Charles Messier listed both in the Messier Catalogue about three days after Koehler's discovery.
Messier 86 is an elliptical or lenticular galaxy in the constellation Virgo. It was discovered by Charles Messier in 1781. M86 lies in the heart of the Virgo Cluster of galaxies and forms a most conspicuous group with another large galaxy known as Messier 84. It displays the highest blue shift of all Messier objects, as it is, net of its other vectors of travel, approaching the Milky Way at 244 km/s. This is due to both galaxies falling roughly towards the center of the Virgo cluster from opposing ends.
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, is centered on Centaurus A, a nearby radio galaxy. The M83 Subgroup, at a distance of 14.9 Mly, is centered on the Messier 83 (M83), a face-on spiral galaxy.
NGC 4309 is a lenticular galaxy located about 55 million light-years away in the constellation Virgo. The galaxy was discovered by astronomer Christian Peters in 1881 and is a member of the Virgo Cluster.
NGC 4323 is a lenticular or dwarf elliptical galaxy located about 52.5 million light-years away in the constellation Coma Berenices. The galaxy was discovered in 1882 by astronomer Wilhelm Tempel and is a member of the Virgo Cluster.
NGC 3260 is an elliptical galaxy in the constellation Antlia. It is a member of the Antlia Cluster, which lies about 40.7 megaparsecs away. It was discovered on May 2, 1834 by the astronomer John Herschel.
NGC 5053 is the New General Catalogue designation for a globular cluster in the northern constellation of Coma Berenices. It was discovered by German-British astronomer William Herschel on March 14, 1784 and cataloged as VI-7. In his abbreviated notation, he described it as, "an extremely faint cluster of extremely small stars with resolvable nebula 8 or 10′ diameter, verified by a power of 240, beyond doubt". Danish-Irish astronomer John Louis Emil Dreyer reported in 1888 that the cluster appeared, "very faint, pretty large, irregular round shape, growing very gradually brighter at the middle".
NGC 4586 is a spiral galaxy located about 50 million light-years away in the constellation Virgo. The galaxy was discovered by astronomer William Herschel on February 2, 1786. Although listed in the Virgo Cluster Catalog, NGC 4586 is considered to be a member of the Virgo II Groups which form a southern extension of the Virgo cluster. NGC 4586 is currently in the process of infalling into the Virgo Cluster and is predicted to enter the cluster in about 500 million years.
NGC 3309 is a giant elliptical galaxy located about 200 million light-years away in the constellation Hydra. NGC 3309 was discovered by astronomer John Herschel on March 24, 1835. The galaxy forms a pair with NGC 3311 which lies about 72,000 ly (22 kpc) away. Both galaxies dominate the center of the Hydra Cluster.
NGC 708 is an elliptical galaxy located 240 million light-years away in the constellation Andromeda and was discovered by astronomer William Herschel on September 21, 1786. It is classified as a cD galaxy and is the brightest member of Abell 262. NGC 708 is a weak FR I radio galaxy and is also classified as a type 2 Seyfert galaxy.
NGC 720 is an elliptical galaxy located in the constellation Cetus. It is located at a distance of circa 80 million light years from Earth, which, given its apparent dimensions, means that NGC 720 is about 110,000 light years across. It was discovered by William Herschel on October 3, 1785. The galaxy is included in the Herschel 400 Catalogue. It lies about three and a half degrees south and slightly east from zeta Ceti.
NGC 1380 is a lenticular galaxy located in the constellation Fornax. It is located at a distance of circa 60 million light years from Earth, which, given its apparent dimensions, means that NGC 1380 is about 85,000 light years across. It was discovered by James Dunlop on September 2, 1826. It is a member of the Fornax Cluster.
NGC 3585 is an elliptical or a lenticular galaxy located in the constellation Hydra. It is located at a distance of circa 60 million light-years from Earth, which, given its apparent dimensions, means that NGC 3585 is about 80,000 light years across. It was discovered by William Herschel on December 9, 1784.
NGC 4636 is an elliptical galaxy located in the constellation Virgo. It is a member of the NGC 4753 Group of galaxies, which is a member of the Virgo II Groups, a series of galaxies and galaxy clusters strung out from the southern edge of the Virgo Supercluster. It is located at a distance of about 55 million light years from Earth, which, given its apparent dimensions, means that NGC 4636 is about 105,000 light years across.
NGC 4294 is a barred spiral galaxy with flocculent spiral arms located about 55 million light-years away in the constellation Virgo. The galaxy was discovered by astronomer William Herschel on March 15, 1784 and is a member of the Virgo Cluster.
NGC 4298 is a flocculent spiral galaxy located about 53 million light-years away in the constellation Coma Berenices. The galaxy was discovered by astronomer William Herschel on April 8, 1784 and is a member of the Virgo Cluster.
NGC 4302 is an edge-on spiral galaxy located about 55 million light-years away in the constellation Coma Berenices. It was discovered by astronomer William Herschel on April 8, 1784 and is a member of the Virgo Cluster.