Hercules A | |
---|---|
Observation data (J2000 epoch) | |
Constellation | Hercules |
Right ascension | 16h 51m 08.15s |
Declination | +04° 59′ 33.32″ |
Redshift | 0.155000 |
Heliocentric radial velocity | 46,468 km/s |
Distance | 2.1 Gly (643.9 Mpc) |
Apparent magnitude (V) | 0.261 |
Apparent magnitude (B) | 0.345 |
Characteristics | |
Type | cD; E3 |
Other designations | |
Herc A, 3C 348, PGC 59117, 4C +05.66, MCG +01-43-006, NRAO 0518 |
Hercules A is a bright astronomical radio source in the constellation Hercules corresponding to the galaxy 3C 348. [1] [2]
During a survey of bright radio sources in the mid-20th century, astronomers found a very bright radio source in the constellation Hercules. The radio source is strongest in the middle range frequency and emits synchrotron radiation, suggesting the source of radio emission may be gravitational interaction. In 1959, astronomers from the Radio Astronomy Group (later the Cavendish Astrophysics Group) detected the radio source using the Cambridge Interferometer of the Cavendish Observatory in Cambridge University in the United Kingdom, including it in the Third Cambridge Catalogue of Radio Sources (3C) as 3C 348, the 348th object detected by the survey.
The galaxy, 3C 348, is a supergiant elliptical galaxy. [3] [4] It is located inside a poor galaxy cluster with an X-ray luminosity of Lbol = 4.8 × 1037 W. [5] 3C 348 is classified as type E3 to E4 of the updated Hubble–de Vaucouleurs extended galaxy morphological classification scheme. It has a companion galaxy, shown appearing as a secondary nucleus, indicating it is merging. [6] [7]
3C 348, the galaxy located in the center of the image, appears to be a relatively normal elliptical galaxy in visible light. When imaged in radio waves, however, plasma jets over one million light years long appear. Detailed analyses indicate that the galaxy is actually over 1,000 times more massive (approx. 1015 solar masses) than our Milky Way Galaxy, and the central black hole is nearly 1,000 times more massive (approx. 4 billion solar masses) than the black hole at our Milky Way's center, one of the largest known. The physics that creates the jets is poorly understood, with a likely energy source being matter ejected perpendicular to the accretion disc of the central black hole [8] which has grown more times than 1.7×108 Msolar, enough to produce a shock front in the cluster's interstellar medium. [9] [10]
The radio source in 3C 348 is considered powerful. [11] It is double-lobed with striking bizarre features such as a double optical core and radio intensity rings clustered together inside one of the host galaxy's two radio lobes. Despite not being a Fanaroff-Riley Class II neither an FR I source, it instead shows similarities to both types. [12] [13]
3C 449 is a low-redshift Fanaroff and Riley class I radio galaxy. It is thought to contain a highly warped circumnuclear disk surrounding the central active galactic nucleus (AGN). The name signifies that it was the 449th object of the Third Cambridge Catalog of Radio Sources (3C), published in 1959.
A super star cluster (SSC) is a very massive young open cluster that is thought to be the precursor of a globular cluster. These clusters called "super" because they are relatively more luminous and contain more mass than other young star clusters. The SSC, however, does not have to physically be larger than other clusters of lower mass and luminosity. They typically contain a very large number of young, massive stars that ionize a surrounding HII region or a so-called "Ultra dense HII region (UDHII)" in the Milky Way Galaxy or in other galaxies. An SSC's HII region is in turn surrounded by a cocoon of dust. In many cases, the stars and the HII regions will be invisible to observations in certain wavelengths of light, such as the visible spectrum, due to high levels of extinction. As a result, the youngest SSCs are best observed and photographed in radio and infrared. SSCs, such as Westerlund 1 (Wd1), have been found in the Milky Way Galaxy. However, most have been observed in farther regions of the universe. In the galaxy M82 alone, 197 young SSCs have been observed and identified using the Hubble Space Telescope.
3C 109 is a Seyfert galaxy located in the constellation Taurus. It is also a broad-line radio galaxy, classified as one of the most active polarized galaxies apart from blazars with quasar-like properties. The black hole in 3C 109 is said to have an estimated mass of 9.3 x 108 M○.
3C 249.1 is a Seyfert galaxy located in the constellation Draco. It hosts a powerful radio source and is located at redshift 0.3115, with a peculiar radio structure. One of its radio lobes is classified as having a Fanaroff-Riley classification Type II, while the other lobe has no features nor containing hotspots.
3C 433 is a Seyfert galaxy located in the constellation Vulpecula. It has a redshift of z =0.1016, and is classified as a peculiar radio galaxy with high luminosity other than its complex shell-type. Apart from that, it has a young stellar population and a radio structure mainly made up of knot and jet structures. Using mid-infrared wavelengths from Spitzer Observations, 3C 433 hosts a hidden quasar.
3C 438 is a Seyfert galaxy and Fanaroff and Riley class II radio galaxy located in the constellation Cygnus. The radio galaxy has two lobes and there is a radio jet leading to the south lobe, which also has a prominent double hot spot. There is age variation across the lobes.
NGC 3862 is an elliptical galaxy located 300 million light-years away in the constellation Leo. Discovered by astronomer William Herschel on April 27, 1785, NGC 3862 is an outlying member of the Leo Cluster.
NGC 6047 is an elliptical galaxy located about 430 million light-years away in the constellation Hercules. It was discovered by astronomer Lewis Swift on June 27, 1886. NGC 6047 is a member of the Hercules 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 4065 is an elliptical galaxy located 300 million light-years away in the constellation Coma Berenices. The galaxy was discovered by astronomer William Herschel on April 27, 1785. It was then rediscovered by John Herschel on April 29, 1832 and was listed as NGC 4057. NGC 4065 is the brightest member of the NGC 4065 Group.
NGC 547 is an elliptical galaxy and radio galaxy located in the constellation Cetus. It is located at a distance of about 220 million light years from Earth, which, given its apparent dimensions, means that NGC 547 is about 120,000 light years across. It was discovered by William Herschel on October 1, 1785. It is a member of the Abell 194 galaxy cluster and is included along with NGC 547 in the Atlas of Peculiar Galaxies.
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.
III Zw 2 is a Seyfert 1 galaxy located in the Pisces constellation. It has a redshift of 0.089 and is notable as the first of its kind to exhibit a superluminal jet.
An extended emission-line region (EELR) is a giant interstellar cloud ionized by the radiation of an active galactic nucleus (AGN) inside a galaxy or photons produced by the shocks associated with the radio jets. An EELR can appear as a resolved cloud in relative nearby galaxies and as narrow emission lines in more distant galaxies.
4C +72.26 known as NAME TX J1908+7220, is a radio galaxy located in the constellation Draco. At the redshift of 3.53, the galaxy is located roughly 11.5 billion light-years from Earth.
4C +41.17 is a radio galaxy located in the constellation Auriga. With the redshift of 3.79, it is located nearly 11.7 billion light-years from Earth. At the time of its discovery in 1988, it was one of the most distant galaxies ever seen.
PKS 1345+125 known as PKS 1345+12 and 4C +12.50, is an ultraluminous infrared galaxy (ULIG) with an active galactic nucleus, located in the constellation Boötes. With a redshift of 0.121740, the galaxy is located 1.7 billion light-years from Earth.
2MASX J17201001+2637317 also known as PGC 1782937, is a massive type-cD elliptical galaxy located in the constellation of Hercules. With redshift of 0.16, the galaxy is located 2.4 billion light-years from Earth and the brightest cluster galaxy in the galaxy cluster, RX J1720.1+2638.
4C +26.42 is an elliptical galaxy located in the constellation of Boötes. It has a redshift of 0.063, estimating the galaxy to be located 863 million light-years from Earth. It has an active galactic nucleus and is the brightest cluster galaxy (BCG) in Abell 1795, an X-ray luminous rich cluster (LX 1045 ergs s-1), with an estimated cooling-flow rate of 300 M yr-1.