NGC 4278 | |
---|---|
Observation data (J2000 epoch) | |
Constellation | Coma Berenices |
Right ascension | 12h 20m 06.8s [1] |
Declination | +29° 16′ 51″ [1] |
Redshift | 0.002068 ± 0.000017 [1] |
Heliocentric radial velocity | 620 ± 5 km/s [1] |
Distance | 55.1 ± 19 Mly (16.9 ± 5.9 Mpc) [1] |
Group or cluster | Coma I |
Apparent magnitude (V) | 10.2 [2] |
Characteristics | |
Type | E1-2 [1] |
Apparent size (V) | 4.1′ × 3.8′ [1] |
Notable features | LINER |
Other designations | |
UGC 7386, CGCG 158-077, MCG +05-29-062, B2 1217+29, PGC 39764 [1] |
NGC 4278 is an elliptical galaxy located in the constellation Coma Berenices. It is located at a distance of circa 55 million light years from Earth, which, given its apparent dimensions, means that NGC 4278 is about 65,000 light years across. It was discovered by William Herschel on March 13, 1785. [3] NGC 4278 is part of the Herschel 400 Catalogue and can be found about one and 3/4 of a degree northwest of Gamma Comae Berenices even with a small telescope. [4]
NGC 4278 is an elliptical galaxy. Its nucleus has been found to be active (AGN) and based on its spectrum has been identified as a LINER. [5] The most accepted theory for the power source of active galactic nuclei is the presence of an accretion disk around a supermassive black hole. In the centre of NGC 4278 lies a supermassive black hole with an estimated mass (3.09±0.54)×108 M☉ based on stellar velocity dispersion. [6] The X-ray emission of the nucleus is consistent with one of a black hole fed by a low radiative efficiency accretion flow. [7]
The nucleus is a source of radio waves and two small symmetric S-shaped radio jets have been observed spanning for 20 mas each, which corresponds to 1.4 parsec at the distance of NGC 4278, emanating from the central source. [8] The nucleus also hosts a compact ultraviolet source, which features strong variability in the form of flares. One such flare was observed between June 1994 and January 1995, when the nuclear source became 1.6 times brighter in six months. Similar flares have also being observed in other low luminosity AGN. [9]
Variability has also being observed in X-rays. The galaxy has been found to brighten 5 times within three years, while fluctuations have been observed in shorter time periods, even within an hour, with the flux increasing by a factor of 10% in one observation by XMM-Newton. The spectrum obtained by XMM-Newton can be accounted for by an absorbed power-law, with column density of the order of 1020 cm-2. The FeKα emission line has not been detected, as is typical for LINERs. The spectral energy distribution of NGC 4278 resembles a LINER at lower fluxes while at higher fluxes it resembles a low luminosity Seyfert galaxy. [10]
Dust features have been observed in the central part of the galaxy [11] and the area that appears northwest of the nucleus. The dust forms knots and filaments that spiral down to the nucleus. [12] Moreover, the galaxy, contrary to most elliptical galaxies which lack neutral hydrogen emission, has been found to possess a massive HI disk, probably formed after the accretion of a dwarf satellite galaxy. [13] The total mass of the HI disk is estimated to be 6.9×108 M☉. The disk rotates at the same sense as the stars, but is misaligned by 20° to 70°. [14] Molecular clouds, as pointed by CO emission, have also been detected in the galaxy. [15]
The galaxy has been observed with the InfraRed Spectrograph (IRS) onboard Spitzer Space Telescope, examining the dust features of NGC 4278. Multiphase gas and dust have been observed in the same elongated features. Another uncommon finding for an elliptical galaxy is the detection of emission by polycyclic aromatic hydrocarbons (PAHs) and of strong [Si II] 34.8-μm emission. PAHs in other elliptical galaxies are believed to be destroyed by the hot interstellar medium. Emission by molecular hydrogen and ionised gas has also been reported. The observed emission of the gas in the nuclear region has been suggested to be the result of the accretion of cold gas by the HI disk. [16]
NGC 4278 is home to a larger than average number of globular clusters compared with galaxies of similar luminosity, with an estimated total number of 1378+32
−194. As it has been found in other galaxies, the colour distribution of the globular clusters in the galaxy features bimodiality, with the clusters forming a red and a blue subpopulation. The blue clusters have been found to be larger than the red ones at the same galactocentric distance, while the size of the clusters increases with galactocentric radius. [17]
NGC 4278 has been identified as a member of a galaxy group known as NGC 4274 or NGC 4062 group. Other members of this group are NGC 4020, NGC 4062, NGC 4136, NGC 4173, NGC 4203, NGC 4245, NGC 4251, NGC 4274, NGC 4283, NGC 4310, NGC 4314, NGC 4359, NGC 4414, NGC 4509, and NGC 4525. [18] Another survey placed NGC 4278 in the same group with NGC 4631, NGC 4656, NGC 4559, NGC 4448, and NGC 4414. [19] It is part of the Coma I Group which is part of the Virgo Supercluster. [20] [21]
NGC 4283 lies 3.5 arcminutes to the northeast and NGC 4286 9 arcminutes northeast of NGC 4278 in the sky. [22] NGC 4274 lies about 20 arcminutes north of NGC 4278. [4]
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 excess, non-stellar emissions have been observed in the radio, microwave, infrared, optical, ultra-violet, X-ray and gamma ray wavebands. A galaxy hosting an AGN is called an active galaxy. The non-stellar radiation from an AGN is theorized to result from the accretion of matter by a supermassive black hole at the center of its host galaxy.
Seyfert galaxies are one of the two largest groups of active galaxies, along with quasar host galaxies. They have quasar-like nuclei with very high surface brightnesses whose spectra reveal strong, high-ionisation emission lines, but unlike quasars, their host galaxies are clearly detectable.
Messier 87 is a supergiant elliptical galaxy in the constellation Virgo that contains several trillion stars. One of the largest and most massive galaxies in the local universe, it has a large population of globular clusters—about 15,000 compared with the 150–200 orbiting the Milky Way—and a jet of energetic plasma that originates at the core and extends at least 1,500 parsecs, traveling at a relativistic speed. It is one of the brightest radio sources in the sky and a popular target for both amateur and professional astronomers.
The Sombrero Galaxy is a peculiar galaxy of unclear classification in the constellation borders of Virgo and Corvus, being about 9.55 megaparsecs from the Milky Way galaxy. It 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 has an isophotal diameter of approximately 29.09 to 32.32 kiloparsecs, making it slightly bigger in size than the Milky Way.
Messier 89 is an elliptical galaxy in the constellation Virgo. It was discovered by Charles Messier on March 18, 1781. M89 is a member of the Virgo Cluster of galaxies.
NGC 3227 is an intermediate spiral galaxy that is interacting with the dwarf elliptical galaxy NGC 3226. The two galaxies are one of several examples of a spiral with a dwarf elliptical companion that are listed in the Atlas of Peculiar Galaxies. Both galaxies may be found in the constellation Leo. It is a member of the NGC 3227 Group of galaxies, which is a member of the Leo II Groups, a series of galaxies and galaxy clusters strung out from the right edge of the Virgo Supercluster.
NGC 3226 is a dwarf elliptical galaxy that is interacting with the spiral galaxy NGC 3227. The two galaxies are one of several examples of a spiral with a dwarf elliptical companion that are listed in the Atlas of Peculiar Galaxies. Both galaxies may be found in the constellation Leo. It is a member of the NGC 3227 Group of galaxies, which is a member of the Leo II Groups, a series of galaxies and galaxy clusters strung out from the right edge of the Virgo Supercluster.
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.
Maffei 1 is a massive elliptical galaxy in the constellation Cassiopeia. Once believed to be a member of the Local Group of galaxies, it is now known to belong to a separate group, the IC 342/Maffei Group. It was named after Paolo Maffei, who discovered it and the neighboring Maffei 2 in 1967 via their infrared emissions.
NGC 6166 is an elliptical galaxy in the Abell 2199 cluster. It lies 490 million light years away in the constellation Hercules. The primary galaxy in the cluster, it is one of the most luminous galaxies known in terms of X-ray emissions.
NGC 3610 is an elliptical galaxy in the constellation Ursa Major. It was discovered on 8 April 1793 by German-British astronomer William Herschel. This galaxy is located at a distance of 106 million light-years (32.5 Mpc) from the Milky Way, and is receding with a galacto-centric radial velocity of 1,819 km/s.
NGC 4478 is an elliptical galaxy located about 50 million light-years away in the constellation Virgo. NGC 4478 was discovered by astronomer William Herschel on April 12, 1784. NGC 4478 is a member of the Virgo 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 7469 is an intermediate spiral galaxy in the constellation of Pegasus. NGC 7469 is located about 200 million light-years away from Earth, which means, given its apparent dimensions, that NGC 7469 is approximately 90,000 light-years across. It was discovered by William Herschel on November 12, 1784.
NGC 1395 is an elliptical galaxy located in the constellation Eridanus. It is located at a distance of circa 75 million light years from Earth, which, given its apparent dimensions, means that NGC 1395 is about 130,000 light years across. It was discovered by William Herschel on November 17, 1784. It is a member of the Eridanus Cluster.
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 5846 is an elliptical galaxy located in the constellation Virgo. It is located at a distance of circa 90 million light years from Earth, which, given its apparent dimensions, means that NGC 5846 is about 110,000 light years across. It was discovered by William Herschel on February 24, 1786. It lies near 110 Virginis and is part of the Herschel 400 Catalogue. It is a member of the NGC 5846 Group of galaxies, itself one of the Virgo III Groups strung out to the east of the Virgo Supercluster of galaxies.
IC 1459 is an elliptical galaxy located in the constellation Grus. It is located at a distance of circa 85 million light-years from Earth, which, given its apparent dimensions, means that IC 1459 is about 130,000 light-years across. It was discovered by Edward Emerson Barnard in 1892.
NGC 1142 is a distorted spiral galaxy in the constellation of Cetus. It is located about 370 million light years away from Earth, which means, given its apparent dimensions, that NGC 1142 is approximately 170,000 light years across. It is a type 2 Seyfert galaxy. It interacts with the elliptical galaxy NGC 1141.