Illustration: Pound et al (MNRAS 2018)Pound and his team looked at an object called the Seyfert galaxy PG1211+143 with the XMM-Newton space telescope.
|
|
Another will map the surface and atmospheres of Jupiter's moons Ganymede and Io. Yet another will peer deep into a Seyfert galaxy, the kind with a bright core.
|
|
NGC 5643 is a Seyfert galaxy; these types have very luminous centers, and scientists think what causes this brightness is a supermassive black hole at the center that sucks up material.
|
|
3C 433 is a Seyfert galaxy located in the constellation Vulpecula.
|
|
3C 438 is a Seyfert galaxy located in the constellation Cygnus.
|
|
3C 452 is a Seyfert galaxy located in the constellation Lacerta.
|
|
3C 61.1 is a Seyfert galaxy located in the constellation Cepheus.
|
|
3C 109 is a Seyfert galaxy located in the constellation Taurus.
|
|
3C 249.1 is a Seyfert galaxy located in the constellation Draco.
|
|
3C 171 is a Seyfert galaxy located in the constellation Lynx.
|
|
3C 215 is a Seyfert galaxy/Quasar located in the constellation Cancer.
|
|
3C 268.3 is a Seyfert galaxy/quasar located in the constellation Ursa Major.
|
|
3C 303 is a Seyfert galaxy with a quasar-like appearance located in the constellation Boötes.
|
|
3C 223 is a Seyfert galaxy with a quasar-like appearance located in the constellation Leo Minor.
|
|
3C 234 is a Seyfert galaxy with a quasar-like appearance located in the constellation Leo Minor.
|
|
NGC 3861 is a low luminosity type II Seyfert galaxy. However, it is also classified as a LINER galaxy.
|
|
NGC 5929 is a Seyfert galaxy in the constellation Boötes. The pair of galaxies, NGC 5929 and NGC 5930, are interacting.
|
|
NGC 3393 has been characterised as a Seyfert galaxy, a galaxy category which features bright point-like nuclei. NGC 3393 is a type II Seyfert galaxy. Its X ray spectrum is more consistent with a Compton-thick cold reflection source, which means that the source is hidden behind dense material, mainly gas and dust, and the X-rays observed have been reflected.
|
|
NGC 2992 is a Seyfert galaxy located in the constellation Hydra. It was discovered in 1785 by William Herschel. It has a close companion, NGC 2993.
|
|
A near-infrared image of NGC 4151. The X-ray landmark NGC 4151, an intermediate spiral Seyfert galaxy has a massive black hole in its core.
|
|
NGC 3081 is known as a Type II Seyfert galaxy, characterised by its dazzling nucleus. Type II Seyfert galaxies have the characteristic bright core, as well as appearing bright when viewed at infrared wavelengths. Their spectra contain narrow lines associated with forbidden transitions, and broader lines associated with allowed strong dipole or intercombination transitions. NGC 3147 is considered the best candidate to be a true Type II Seyfert galaxy.
|
|
NGC 3941 is type 2 Seyfert galaxy. In the centre of the galaxy lies a supermassive black hole whose mass is estimated to be, based on velocity dispersion, 141 million (108.14) .
|
|
3C 219 is a Seyfert galaxy with a quasar-like appearance located in the constellation Ursa Major. This galaxy's radio jets are not detectable between the core and the outer radio lobes.
|
|
NGC 4939 has been characterised as a Seyfert galaxy, a galaxy category which features bright point-like nuclei. NGC 4939 is a type II Seyfert galaxy. Its X ray spectrum is more consistent with a Compton-thick cold reflection source, which means that the source is hidden behind dense material, mainly gas and dust, and the X-ray observed have been reflected, but a Compton-thin transmission model could not be ruled out. The equivalent width of the FeKα line is large, indicating too that it is a Compton-thick source.
|
|
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.
|
|
It is a Seyfert galaxy, the only one in Fornax Cluster. NGC 1427A is an irregular galaxy in the constellation Eridanus. Its distance modulus has been estimated using the globular cluster luminosity function to be 31.01 ± 0.21 which is about 52 Mly.
|
|
Markarian 231 (UGC 8058) is a Type-1 Seyfert galaxy that was discovered in 1969 as part of a search of galaxies with strong ultraviolet radiation. It contains the nearest known quasar. Markarian 231 is located about 581 million light years away from Earth.
|
|
The nucleus of NGC 973 appears to be active based on its emission. It is categorised as a type 2 Seyfert galaxy. The most accepted theory for the energy source of active galactic nuclei is the presence of an accretion disk around a supermassive black hole.
|
|
The IUE vastly increased astronomers' understanding of active galactic nuclei (AGN). Before its launch, 3C 273, the first known quasar, was the only AGN that had ever been observed at UV wavelengths. With IUE, UV spectra of AGN became widely available. One particular target was NGC 4151, the brightest Seyfert galaxy.
|
|
Other notable objects in Caelum are RR Caeli, a binary star with one known planet approximately away; X Caeli, a Delta Scuti variable that forms an optical double with γ 1 Caeli; and HE0450-2958, a Seyfert galaxy that at first appeared as just a jet, with no host galaxy visible.
|
|
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, the only one in Fornax Cluster.
|
|
NGC 985 is a ring galaxy in the constellation of Cetus. It is located about 550 million light years away from Earth, which means, given its apparent dimensions, that NGC 985 is approximately 160,000 light years across. It was discovered by Francis Leavenworth in 1886. It is a type 1 Seyfert galaxy.
|
|
NGC 5643 is an intermediate spiral galaxy in constellation Lupus. It is located at a distance of circa 60 million light years from Earth, which, given its apparent dimensions, means that NGC 5643 is about 100,000 light years across. NGC 5643 has an active galactic nucleus and is a type II Seyfert galaxy.
|
|
The Hubble Ultra Deep Field seen with MUSE. Outside NGC 1097 is a barred spiral galaxy in Fornax, about 45 million light- years from Earth. At magnitude 9, it is visible in medium amateur telescopes. It is notable as a Seyfert galaxy with strong spectral emissions indicating ionized gases and a central supermassive black hole.
|
|
Several supernovae have been discovered in NGC 4051: SN 1983I, SN 2010br, and SN 2003ie. The galaxy is a Seyfert galaxy that emits bright X-rays. However, in early 1998 the X-ray emission ceased as observed in by the Beppo-SAX satellite. X-ray emission had risen back to normal by August 1998.
|
|
This galaxy used to be classified as a Seyfert 2 galaxy, but that is probably incorrect. Recent X-ray observations provide no evidence of any active galactic nucleus (AGN) activity, and high resolution optical spectra do not confirm the status of NGC 6810 as a Seyfert galaxy, thus it appears to have been misclassified.
|
|
NGC 1161 is a lenticular galaxy approximately 90 million light-years away from Earth in the constellation of Perseus. It was discovered, along with NGC 1160, by English astronomer William Herschel on October 7, 1784. NGC 1161 is classified as a Type 1.9 Seyfert galaxy. It forms a visual pair with the galaxy NGC 1160.
|
|
NGC 1097 is also a Seyfert galaxy. Deep photographs revealed four narrow optical jets that appear to emanate from the nucleus. These have been interpreted as manifestations of the (currently weak) active nucleus. Subsequent analysis of the brightest jet's radio-to-X-ray spectral energy distribution were able to rule out synchrotron and thermal free-free emission.
|
|
NGC 1241 is a spiral galaxy located in the constellation Eridanus. It is located at a distance of circa 150 million light years from Earth, which, given its apparent dimensions, means that NGC 1241 is about 140,000 light years across. It was discovered by William Herschel on January 10, 1785. It is classified as a Seyfert galaxy.
|
|
NGC 3367 has been categorised as a HII region or a type 2 Seyfert galaxy. However, optically there is no hint of an Active Galactic Nucleus (AGN). The spectrum of NGC 3367 features unusually broad lines (FWHM of 490 m/s for Hβ) and a blue asymmetry. The spectrum looks like one produced from Wolf-Rayet stars.
|
|
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. It is classified as a Seyfert galaxy and as a LINER galaxy. It also has a prominent, extended dust lane.
|
|
NGC 4074 is a peculiar lenticular galaxy located 310 million light-years away in the constellation Coma Berenices. It was discovered by astronomer William Herschel on April 27, 1785 and is a member of the NGC 4065 Group. NGC 4074 is classified as a type 2 Seyfert galaxy. It was first identified as a Seyfert in 1978.
|
|
NGC 612 is a lenticular galaxy in the constellation of Sculptor located approximately 388 million light-years from Earth. It is a type II Seyfert galaxy and thus has an active galactic nucleus. NGC 612 has been identified as an extremely rare example of a non-elliptical radio galaxy, hosting one of the nearest powerful FR-II radio sources.
|
|
NGC 931 is a spiral galaxy located in the constellation Triangulum. It is located at a distance of circa 200 million light years from Earth, which, given its apparent dimensions, means that NGC 931 is about 200,000 light years across. It was discovered by Heinrich d'Arrest on September 26, 1865. It is classified as a Seyfert galaxy.
|
|
NGC 4313 is an edge-on spiral galaxy located about 50 million light-years away in the constellation Virgo. It was discovered by astronomer William Herschel on March 15, 1784. NGC 4313 is a member of the Virgo Cluster and is classified as LINER and as a Seyfert galaxy. NGC 4313 has undergone ram-pressure stripping in the past.
|
|
NGC 4316 is an edge-on spiral galaxy located about 70 million light-years away in the constellation Virgo. It was discovered by astronomer Wilhelm Tempel on March 17, 1882. NGC 4316 is a member of the Virgo Cluster and is classified as LINER and as a Seyfert galaxy. The galaxy has undergone ram-pressure stripping in the past.
|
|
It has a Seyfert 2 active galactic nucleus, and is one of the most extreme examples of a Seyfert galaxy. This galaxy may be associated with gamma-ray source 3EG J1621+8203, which has high-energy gamma-ray emission. It is also noted for its one-sided radio jet—one of the brightest known—discovered in 1977.
|
|
NGC 4477 is a barred lenticular galaxy located about 55 million light-years away in the constellation of Coma Berenices. NGC 4477 is classified as a type 2 seyfert galaxy. The galaxy was discovered by astronomer William Herschel on April 8, 1784. NGC 4477 is a member of Markarian's Chain which forms part of the larger Virgo Cluster.
|
|
NGC 3884 is a spiral galaxy located about 330 million light-years away in the constellation Leo. The galaxy was discovered by astronomer William Herschel on April 27, 1785 and is a member of the Leo Cluster. Although it is classified as a LINER galaxy, NGC 3884 is also classified as a type 1 seyfert galaxy.
|
|
NGC 3081 is a barred lenticular ring galaxy in the constellation of Hydra. NGC 3081 is located about 85 million light-years away from Earth, which means, given its apparent dimensions, that NGC 3081 is approximately 60,000 light years across. It is a type II Seyfert galaxy, characterised by its bright nucleus. It was discovered by William Herschel on 21 December 1786.
|
|
The Milky Way runs through the constellation, featuring prominent objects such as the open cluster NGC 5823 and the planetary nebula NGC 5315. Circinus hosts a notable spiral galaxy, the Circinus Galaxy, discovered in 1977; it is the closest Seyfert galaxy to the Milky Way. The Alpha Circinids (ACI), a meteor shower also discovered in 1977, radiate from this constellation.
|
|
NGC 2655 from Planewave CDK24 in Julian, CA NGC 2655 is a lenticular galaxy in the constellation Camelopardalis. It is at a distance of 60 million light years from Earth. NGC 2655 is a Seyfert galaxy. The galaxy has asymmetric dust lanes in the centre of the galaxy, tidal arms and extended neutral hydrogen gas and may have recently experienced a merger.
|
|
NGC 5930 is a starburst galaxy in the constellation Boötes that is interacting with the nearby Seyfert galaxy NGC 5929. 5930 has a morphological classification of SAB(rs)b pec, indicating that it is a weakly-barred spiral galaxy with a poorly defined nuclear ring structure. It is inclined at an angle of 46° to the line of sight from the Earth.
|
|
NGC 2681 is a lenticular galaxy in the constellation Ursa Major. The galaxy lies 50 million light years away from Earth, which means, given its apparent dimensions, that NGC 2681 is approximately 55,000 light years across. NGC 2681 has an active galactic nucleus and it is a type 3 Seyfert galaxy. Its nucleus is also a low-ionization nuclear emission-line region.
|
|
The nucleus of NGC 6951 is active. It has been classified both as a type 2 Seyfert galaxy and a LINER and it has been suggested that it is in transition form, between a Seyfert galaxy and a very-high-excitation LINER, with very strong [N II] and [S II] lines. A supermassive black hole which accretes material in the centre of the galaxy is believed to be the cause of the nuclear activity. The upper mass limit of the supermassive black hole at the centre of NGC 6951 is estimated to be between 6 and 14 million based on velocity dispersion. Molecular gas, most probably a circumnuclear dust disk or torus less than 50 parsec in radius, has been detected around the nucleus. Around the nucleus of NGC 6951 has been observed a star formation ring with a radius of 5 arcseconds.
|
|
NGC 1097 is an example of a Seyfert galaxy. A supermassive black hole with a mass of 100 million solar masses lies at the center of the galaxy. The area around the black hole emits large amounts of radiation from the matter falling into the black hole. Seyferts were first classified as Type I or II, depending on the emission lines shown by their spectra.
|
|
The nucleus of this galaxy is filled with many young stars, due to the star formation caused by the merger. Because there is a such a large amount, NGC 2623 is classified as a Seyfert Galaxy. Seyfert Galaxies have very bright cores and similar properties to quasars. Both are nuclei of galaxies that contain active super massive black holes and emit very high levels of energy.
|
|
LEDA 83677 is a lenticular galaxy located about 290 million light-years away in the constellation Coma Berenices. It is a member of the Coma cluster of galaxies. LEDA 83677 is also classified as a type 1 Seyfert galaxy. The core of the galaxy is emitting high-energy X-rays and ultraviolet light, probably caused by a massive black hole lurking in the core.
|
|
It appears face-on and has a clearly visible nucleus of magnitude 10. About 50 million light-years from Earth, M77 is also a Seyfert galaxy and thus a bright object in the radio spectrum. Recently, the galactic cluster JKCS 041 was confirmed to be the most distant cluster of galaxies yet discovered. The massive cD galaxy Holmberg 15A is also found in Cetus.
|
|
NGC 7213 is a lenticular galaxy located in the constellation Grus. It is located at a distance of circa 70 million light years from Earth, which, given its apparent dimensions, means that NGC 7213 is about 75,000 light years across. It was discovered by John Herschel on September 30, 1834. It is an active galaxy with characteristics between a type I Seyfert galaxy and LINER.
|
|
NGC 2768 is a lenticular galaxy located in the constellation of Ursa Major. It is at a distance of 65 million light years from Earth. NGC 2768 is an example of a Seyfert galaxy, an object with a supermassive black hole at its centre. A dusty structure is encircling the centre of the galaxy, forming a knotted ring around the galaxy's brightly glowing middle.
|
|
NGC 6814 is an intermediate spiral galaxy in constellation Aquila. It is located at a distance of about 75 million light years from Earth, which, given its apparent dimensions, means that NGC 6814 is about 85,000 light years across. NGC 6814 has an extremely bright nucleus and is a type 1.5 Seyfert galaxy. The galaxy is also a highly variable source of X-ray radiation.
|
|
NGC 1386 has an active galactic nucleus (AGN) that has been categorised as a type 2 Seyfert galaxy. It is one of the nearest Seyfert galaxies. The source of nuclear activity in galaxies is suggested to be material accretion around a supermassive black hole in the galactic centre. The black hole in the centre of NGC 1386 is estimated to be based on stellar velocity dispersion.
|
|
This is a type 2 Seyfert galaxy with one of the largest circumnuclear outflows known in galaxies of this type. This outflow reaches velocities of up to and spans . The star formation rate appears normal for a spiral galaxy at yr−1, and the majority (68%) is occurring in the spiral arms. The core appears faint in the ultraviolet band, indicating heavy extinction within the active galactic nucleus.
|
|
NGC 7603 is a spiral Seyfert galaxy in the constellation Pisces. It is listed (as Arp 92) in the Atlas of Peculiar Galaxies. It is interacting with the smaller elliptical galaxy PGC 71041 nearby. This galaxy pair has long been a cornerstone for those who are critical of the view that the universe is expanding, and advocates for Non-standard cosmology such as Halton Arp, Fred Hoyle, and others.
|
|
This is a Type II Seyfert galaxy with an active galactic nucleus. A dust lane is seen crossing the nucleus, and there are indications of recent starburst activity nearby. NGC 289 is a giant, gas-rich, low surface brightness galaxy with a small bulge at the nucleus, a small central bar, and two inner spiral arms. These arms split into multiple parts as they extend into the outer disk.
|
|
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. Dust features have been observed in the central part of the galaxy and the area that appears northwest of the nucleus. The dust forms knots and filaments that spiral down to the nucleus.
|
|
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 708 is surrounded by 4700 globular clusters.
|
|
NGC 5793 is an active spiral galaxy located approximately 150 million light years away in the constellation Libra. It is classified as a seyfert galaxy and was discovered by Francis Leavenworth in 1886. In 2014, the Hubble Space Telescope examined and photographed NGC 5793. Seyfert galaxies such as NGC 5793 are known to house megamasers, these megamasers are capable of having a luminosity of thousands of times greater than the Sun.
|
|
NGC 1142 and NGC 1141 imaged by the Sloan Digital Sky Survey NGC 1142 (also known as NGC 1144) 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.
|
|
The Circinus Galaxy (ESO 97-G13) is a Seyfert galaxy in the constellation of Circinus. It is located 4 degrees below the Galactic plane, and, at a distance of , and is one of the closest galaxies to the Milky Way. The galaxy is undergoing tumultuous changes, as rings of gas are likely being ejected from the galaxy. Its outermost ring is 1400 light-years across while the inner ring is 260 light-years across.
|
|
Down are some famous objects in this cluster: NGC 1365 is another barred spiral galaxy located at a distance of 56 million light-years from Earth. Like NGC 1097, it is also a Seyfert galaxy. Its bar is a center of star formation and shows extensions of the spiral arms' dust lanes. The bright nucleus indicates the presence of an active galactic nucleus – a galaxy with a supermassive black hole at the center, accreting matter from the bar.
|
|
This star, located away, is a K-type subgiant of spectral type K1. The other twelve naked-eye stars in Caelum are not referred to by Bode's Bayer designations anymore, including RV Caeli. alt=An image of the Seyfert galaxy HE0450-2958, showing the active nucleus One of the nearest stars in Caelum is the eclipsing binary star RR Caeli, at a distance of . This star system consists of a dim red dwarf and a white dwarf.
|
|
NGC 3281 is a large unbarred spiral galaxy in the southern constellation of Antlia, located at a distance of from the Milky Way. The galaxy is inclined by an angle of 64° to the line-of-sight from the Earth, with the major axis aligned with a position angle of 137°. It is a luminous infrared galaxy and a type II Seyfert galaxy. NGC 3281 is a member of the Antlia Cluster, which belongs to the Hydra-Centaurus Supercluster.
|
|
This was followed by a PPARC Advanced Fellowship held at the University of Edinburgh. His research interests include active galactic nuclei (particularly Seyfert galaxy, Radio galaxy and quasars) and the ways in which large galaxies and their central supermassive black holes have changed and evolved throughout cosmological time. This research has involved the use of a variety of telescopes, including the Hubble Space Telescope, the Very Large Array, MERLIN, the William Herschel Telescope, and the Very Large Telescope.
|
|
The central part of NGC 4636 is circular and is surrounded by an elongated fainter envelope, containing a large number of globular clusters.Sandage, A., Bedke, J. (1994), The Carnegie Atlas of Galaxies. Volume I, Carnegie Institution of Washington The galaxy has an active galactic nucleus (AGN) that has been categorised as LINER or a type 1.9 Seyfert galaxy. The source of nuclear activity in galaxies is suggested to be a supermassive black hole that accretes material.
|
|
NGC 3081 is known to feature an active galaxy nucleus which is categorised as type II Seyfert galaxy. Even though NGC 3081 shows significant absorption, it is Compton thin. Also it does not show spectral variability on monthly timescales in X-rays. In the nucleus of the galaxy is thought to exist a supermassive black hole whose mass upper limit is estimated to be between 8.5 and 37 million , based on the intrinsic velocity dispersion as measured by the Hubble Space Telescope.
|
|
It was discovered by musician-astronomer William Herschel in 1784 and was later one of the first nebulous objects to be described as "spiral" by William Parsons. Another of Pegasus's galaxies is NGC 7742, a Type 2 Seyfert galaxy. Located at a distance of 77 million light-years with a redshift of 0.00555, it is an active galaxy with a supermassive black hole at its core. Its characteristic emission lines are produced by gas moving at high speeds around the central black hole.
|
|
It is classified as an Sbc spiral, which lies between the Sb and Sc categories of medium-wound and loosely wound spiral arms, respectively. The arm structure of the spirals is very regular and can be followed down to the galactic core. The maximum rotation velocity of the gas is 241.6 ± 4.5 km/s. M88 is also classified as a type 2 Seyfert galaxy, which means it produces narrow spectral line emission from highly ionized gas in the galactic nuclei.
|
|
There is evidence of star formation, but that has nearly ceased in the nuclear region due to the molecular gas being all but exhausted. The nuclear bar, if it exists, now consists of stars with little surrounding gas. This is a Seyfert galaxy of type 1.9, indicating it has an obscured active galactic nucleus (AGN) powered by a supermassive black hole at the center. The estimated mass of this object is and it is accreting mass at the rate of .
|
|
These authors concluded that the "naked" quasar was in fact a perfectly normal, narrow-line Seyfert galaxy that happened to lie close on the sky to a disturbed galaxy. The "quasar without a home". A number of scientific studies since 2005 have supported this conclusion. (1) Kim et al. (2006) Kim, M. et al. (2006), The Host Galaxy of the Quasar HE 0450-2958, The Astrophysical Journal, 658, 107 made a more careful attempt to find the quasar's host galaxy.
|
|
NGC 1275, a component of the cluster, is a Seyfert galaxy containing an active nucleus that produces jets of material, surrounding the galaxy with massive bubbles. These bubbles create sound waves that travel through the Perseus Cluster, sounding a B flat 57 octaves below middle C. This galaxy is a cD galaxy that has undergone many galactic mergers throughout its existence, as evidenced by the "high velocity system"—the remnants of a smaller galaxy—surrounding it. Its active nucleus is a strong source of radio waves.
|
|
NGC 7479 (also known as Caldwell 44) is a barred spiral galaxy about 105 million light-years away in the constellation Pegasus. It was discovered by William Herschel in 1784. Supernovae SN 1990U and SN2009jf occurred in NGC 7479. NGC 7479 is also recognized as a Seyfert galaxy and a Liner undergoing starburst activity not only on the nucleus and the outer arms, but also across the bar of the galaxy, where most of the stars were formed in the last 100 million years.
|
|
Markarian 335 is a Seyfert galaxy containing a supermassive black hole, located 324 million light-years away in the constellation of Pegasus. The central black hole in this active galaxy nucleus is notable for its corona's spinning rate (at about 20 percent the speed of light) and its change in brightness from 2007 to 2014. The geometry of the corona has been deduced from relativistic blurring of the reflection of the accretion disc. An x-ray flare in 2013 is interpreted as an aborted jet.
|
|
NGC 6251 is an active supergiant elliptical radio galaxy in the constellation Ursa Minor, and is more than 340 million light-years away from Earth. The galaxy has a Seyfert 2 active galactic nucleus,SIMBAD and is one of the most extreme examples of a Seyfert galaxy. This galaxy may be associated with gamma-ray source 3EG J1621+8203, which has high-energy gamma-ray emission. It is also noted for its one-sided radio jet—one of the brightest known—discovered in 1977.
|
|
"unresolved"), have high mass (≈109±1 solar masses), and the duration of peak nuclear emissions is relatively short (> 108 years). NGC 5793 is a Seyfert galaxy located over 150 million light-years away in the constellation of Libra. In the 1960s and 1970s, research to further understand the properties of Seyfert galaxies was carried out. A few direct measurements of the actual sizes of Seyfert nuclei were taken, and it was established that the emission lines in NGC 1068 were produced in a region over a thousand light years in diameter.
|
|
Inside the circumnuclear ring was detected a bar like feature 1.6 arseconds long that is almost perpendicular to the main bar of the galaxy. The nucleus of NGC 1241 has been found to be active and it has been categorised as a type II Seyfert galaxy. The most accepted theory for the energy source of active galactic nuclei is the presence of an accretion disk around a supermassive black hole. The mass of the black hole in the centre of NGC 1241 is estimated to be 107.46 (29 million) .
|
|
NGC 3486 is an intermediate barred spiral galaxy located about 27.4 million light years away in the constellation of Leo Minor. It has a morphological classification of SAB(r)c, which indicates it is a weakly barred spiral with an inner ring and loosely wound arms. This is a borderline, low-luminosity Seyfert galaxy with an active nucleus. However, no radio or X-ray emission has been detected from the core, and it may only have a small supermassive black hole with less than a million times the mass of the Sun.
|
|
In the infrared K-band a bar is visible. The total infrared luminosity of NGC 7130 is (1011.35 ) and it is categorised as a luminous infrared galaxy. NGC 7130 has a bright nucleus which is characterised as active. The galaxy features optical emission lines typical of a type 2 Seyfert galaxy, with broad lines and strong emission lines from high ionisation elements, like [He II], however the ultraviolet spectrum is more consistent with the emission produced by young, massive O-type stars, suggesting an active starburst in the nucleus.
|
|
In the nuclear region of NGC 3489 has been observed dust with an open spiral pattern. The galaxy has an outer ring structure, with a diameter of 1.54 arcminutes along the major axis. NGC 3489 has an active galactic nucleus, which has been categorised based on its spectrum as a type 2 Seyfert galaxy or, based on the nuclear [O I] emission strength, which lies between that of H II nuclei and LINER, a transition object. This kind of transition emission could be attributed to post AGB stars located in the core.
|
|
NGC 5548 is a Type I Seyfert galaxy with a bright, active nucleus. This activity is caused by matter flowing onto a 65 million solar mass () supermassive black hole at the core. Morphologically, this is an unbarred lenticular galaxy with tightly-wound spiral arms, while shell and tidal tail features suggest that it has undergone a cosmologically-recent merger or interaction event. NGC 5548 is approximately 245 million light years away and appears in the constellation Boötes. The apparent visual magnitude of NGC 5548 is approximately 13.3 in the V band.
|
|
The nucleus of NGC 931 has been found to be active and it has been categorised as a type I Seyfert galaxy due to its narrow H-beta emission line. The most accepted theory for the energy source of active galactic nuclei is the presence of an accretion disk around a supermassive black hole. The mass of the black hole in the centre of NGC 931 is estimated to be 107.64 ± 0.40 (17- 110 million) based on the stellar velocity dispersion. NGC 931 has been found to emit radiowaves, ultraviolet and X-rays.
|
|
In the centre of the galaxy lies a supermassive black hole, whose mass is estimated to be 106.46 ± 0.33 (1.3 - 6.2 million) , based on the pitch angle of the spiral arms. The galaxy had been classified as a type 1 Seyfert galaxy, however it features only narrow emission lines, and has been reclassified as a HII region galaxy. The Infrared Spectrograph (IRS) on the Spitzer Space Telescope has detected polycyclic aromatic hydrocarbon (PAH) emission. NGC 3511 forms a pair with NGC 3513, which lies 10.5 arcminutes away from NGC 3511.
|
|
A ring observation in O III images may be associated with the inner bar or a nuclear ring. The nucleus of the galaxy has been found to be active and it has been categorised as a type 2 Seyfert galaxy. The most accepted theory for the energy source of active galactic nuclei is the presence of an accretion disk around a supermassive black hole. The mass of the black hole in the centre of NGC 2974 is estimated to be between 140 and 210 million (10) based on the stellar velocity dispersion.
|
|
Optical and ultraviolet images of the black hole in the center of NGC 4151, a Seyfert Galaxy An active galactic nucleus (AGN) is a compact region at the center of a galaxy that has a higher than normal luminosity over portions of the electromagnetic spectrum. A galaxy having an active nucleus is called an active galaxy. Active galactic nuclei are the most luminous sources of electromagnetic radiation in the Universe, and their evolution puts constraints on cosmological models. Depending on the type, their luminosity varies over a timescale from a few hours to a few years.
|
|
The emission lines seen on the spectrum of a Seyfert galaxy may come from the surface of the accretion disc itself, or may come from clouds of gas illuminated by the central engine in an ionization cone. The exact geometry of the emitting region is difficult to determine due to poor resolution of the galactic center. However, each part of the accretion disc has a different velocity relative to our line of sight, and the faster the gas is rotating around the black hole, the broader the emission line will be. Similarly, an illuminated disc wind also has a position-dependent velocity.
|
|
NGC 6814 is a Seyfert galaxy with a highly variable source of X-ray radiation. Type I Seyferts are very bright sources of ultraviolet light and X-rays in addition to the visible light coming from their cores. They have two sets of emission lines on their spectra: narrow lines with widths (measured in velocity units) of several hundred km/s, and broad lines with widths up to 104 km/s. The broad lines originate above the accretion disc of the supermassive black hole thought to power the galaxy, while the narrow lines occur beyond the broad line region of the accretion disc.
|
|
NGC 3147 has been characterised as a Seyfert II galaxy. It is considered the best candidate to be a true type II Seyfert galaxy, galaxies which feature optical/UV spectrum lacking broad emission lines due to the lack of the broad line region rather than its obscuration, since the nucleus is simultaneously seen unobscured in the X-rays. The galaxy was observed stimultaneously in the optical and X-ray spectrum by Bianchi et al. and concluded that the X-ray spectrum is unabsorbed while its optical spectrum lacks broad lines, a mismatch with respect to the Unification Model.
|
|
NGC 1142 is one of most luminous galaxies in the local universe as far as CO emission is concerned, twice as bright as the merger remnant Arp 220. Most of the emission originates from the ring, and especially its southern part, and a giant HII region west of the nucleus. The nucleus of NGC 1142 has been found to be active and it has been categorised as a type II Seyfert galaxy. The most accepted theory for the energy source of active galactic nuclei is the presence of an accretion disk around a supermassive black hole.
|
|
It measures 3.9 by 2.0 arcminutes. Other galaxies include NGC 5008, a type Sc emission-line galaxy, NGC 5548, a type S Seyfert galaxy, NGC 5653, a type S HII galaxy, NGC 5778 (also classified as NGC 5825), a type E galaxy that is the brightest of its cluster, NGC 5886, and NGC 5888, a type SBb galaxy. NGC 5698 is a barred spiral galaxy, notable for being the host of the 2005 supernova SN 2005bc, which peaked at magnitude 15.3. Further away lies the 250-million-light-year-diameter Boötes void, a huge space largely empty of galaxies.
|
|
NGC 4237 is a flocculent spiral galaxy located about 60 million light-years away in the constellation Coma Berenices. The galaxy was discovered by astronomer William Herschel on December 30, 1783 and is a member of the Virgo Cluster. It is also classified as a LINER galaxy and as a Seyfert galaxy. NGC 4237 appears to be deficient in neutral atomic hydrogen (H I). This, combined with its large projected distance from M87 and its radial velocity close to the Virgo Cluster mean suggests that the galaxy may be on a highly radial orbit through the center of the cluster.
|
|
The two largest subclasses of active galaxies are quasars and Seyfert galaxies, the main difference between the two being the amount of radiation they emit. In a typical Seyfert galaxy, the nuclear source emits at visible wavelengths an amount of radiation comparable to that of the whole galaxy's constituent stars, while in a quasar, the nuclear source is brighter than the constituent stars by at least a factor of 100. Seyfert galaxies have extremely bright nuclei, with luminosities ranging between 108 and 1011 solar luminosities. Only about 5% of them are radio bright; their emissions are moderate in gamma rays and bright in X-rays.
|
|
NGC 1275, a Type 1.5 Seyfert galaxy In 1981, Donald Osterbrock introduced the notations Type 1.5, 1.8 and 1.9, where the subclasses are based on the optical appearance of the spectrum, with the numerically larger subclasses having weaker broad-line components relative to the narrow lines. For example, Type 1.9 only shows a broad component in the Hα line, and not in higher order Balmer lines. In Type 1.8, very weak broad lines can be detected in the Hβ lines as well as Hα, even if they are very weak compared to the Hα. In Type 1.5, the strength of the Hα and Hβ lines are comparable.
|
|
SN 2001ig was discovered in 2001 and classified as a Type IIb supernova, one that initially showed a weak hydrogen line in its spectrum, but this emission later became undetectable and was replaced by lines of oxygen, magnesium and calcium, as well as other features that resembled the spectrum of a Type Ib supernova. A massive star of spectral type F, A or B is thought to be the surviving binary companion to SN 2001ig, which was believed to have been a Wolf–Rayet star. Located near Alnair is NGC 7213, a face-on type 1 Seyfert galaxy located approximately 71.7 million light-years from Earth.
|
|
NGC 4151 is an intermediate spiral seyfert galaxy with weak inner ring structure located from Earth in the constellation Canes Venatici. The galaxy was first mentioned by William Herschel on March 17, 1787; it was one of the two Seyfert galaxies described in the paper which defined the term. It is one of the nearest galaxies to Earth to contain an actively growing supermassive black hole; it was speculated that the nucleus may host a binary black hole, with about 40 million and about 10 million solar masses respectively, orbiting with a 15.8-year period. This is, however, still a matter of active debate.
|
|
Based on the emission lines that are present in its spectrum, the nucleus of NGC 2273 has been characterised as active and it has been categorised as a type II Seyfert galaxy. Also, a water kilomaser has been detected in the nuclear region of the galaxy. It could be created either by the active nucleus or by a prominent site of star formation. Observations by BeppoSAX, XMM Newton, and Chandra X-Ray Observatory suggested that the nucleus of NGC 2273 is obscured by a Compton thick column, with high column density, estimated to be cm−2 as measured by ASCA, or cm−2 as measured by Suzaku.
|
|
Discovered in 1977, it is a relatively unobscured galaxy (magnitude 10.6), which is unusual for galaxies located in constellations near the Milky Way, since their dim light is obscured by gas and dust. This oblong spiral galaxy with 6.9 by 3.0 arcminutes and 26,000 light-years in diameter, is located 13 million light-years away from Earth and lies 4 degrees off the galactic plane. It is the closest Seyfert galaxy to the Milky Way, and therefore hosts an active galactic nucleus. The Chandra X-ray Observatory's false-color image of Circinus X-1 showing its jets Circinus X-1 is an X-ray binary star system that includes a neutron star.
|
|
The nucleus of NGC 7213 features activity and belongs to the low luminosity Active Galactic Nuclei (LLAGN). The optical spectrum features broad H-alpha lines and has similar characteristics to a type I Seyfert galaxy, however it is considerably less luminous than other similar galaxies. It also features [Ne V] λ3426, He II λ4686, [O II] λ3726, 3729, 7319, 7330, [O III] λ4363, 4959, and 5007 emission lines. However the intensity ratios of many of these lines is similar to a LINER. Observed in radio waves, NGC 7213 looks like a point-like source that could feature two jets that bend between one 1 arcsec (150 pc) and 10 arcsec (1.5 kpc).
|
|
Searches for a compact stellar remnant have been largely concentrated here, as the hole may have been caused by the violent ejection of a neutron star. A detailed 2012 study of the blowout region identified a possible pulsar wind nebula, as well as a point-like source within it. Although at almost exactly the same position as a known Seyfert galaxy, the slight offset combined with a lack of a radio counterpart makes the point-like source probably unrelated to the galaxy. Whether or not the feature is a pulsar wind nebula or not, and if so whether or not it is related to the Cygnus Loop, is still unknown for certain.
|
|
The Circinus Galaxy, a Type II 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.
|
|
Due to its small size and location away from the plane of the Milky Way, Caelum is rather devoid of deep-sky objects, and contains no Messier objects. The only deep-sky object in Caelum to receive much attention is HE0450-2958, an unusual Seyfert galaxy. Originally, the jet's host galaxy proved elusive to find, and this jet appeared to be emanating from nothing. Although it has been suggested that the object is an ejected supermassive black hole, the host is now agreed to be a small galaxy that is difficult to see due to light from the jet and a nearby starburst galaxy. The 13th magnitude planetary nebula PN G243-37.1 is also in the eastern regions of the constellation.
|
|
Although the Circinus galaxy can be seen using a small telescope, it was not noticed until 1977 because it lies close to the plane of the Milky Way and is obscured by galactic dust. The Circinus Galaxy is a Type II Seyfert galaxy and is one of the closest known active galaxies to the Milky Way, though it is probably slightly farther away than Centaurus A. Circinus Galaxy produced supernova SN 1996cr, which was identified over a decade after it exploded. This supernova event was first observed during 2001 as a bright, variable object in a Chandra X-ray Observatory image, but it was not confirmed as a supernova until years later. The Circinus Galaxy is one of twelve large galaxies in the "Council of Giants" surrounding the Local Group in the Local Sheet.
|
|
The AGN could merely be closely associated with the actual sources, for example in galaxies or other astrophysical objects that are clumped with matter on large scales within 100 megaparsecs. Some of the supermassive black holes in AGN are known to be rotating, as in the Seyfert galaxy MCG 6-30-15 with time-variability in their inner accretion disks. Black hole spin is a potentially effective agent to drive UHECR production, provided ions are suitably launched to circumvent limiting factors deep within the galactic nucleus, notably curvature radiation and inelastic scattering with radiation from the inner disk. Low-luminosity, intermittent Seyfert galaxies may meet the requirements with the formation of a linear accelerator several light years away from the nucleus, yet within their extended ion tori whose UV radiation ensures a supply of ionic contaminants.
|
|