NGC 7469 | |
---|---|
Observation data (J2000 epoch) | |
Constellation | Pegasus |
Right ascension | 23h 03m 15.6s [1] |
Declination | +08° 42′ 26″ [1] |
Redshift | 0.016317 ± 0.000007 [1] |
Heliocentric radial velocity | 4,892 ± 2 km/s [1] |
Distance | 195 ± 65.6 Mly (60.0 ± 20.1 Mpc) [1] |
Apparent magnitude (V) | 12.3 |
Characteristics | |
Type | (R')SAB(rs)a [1] |
Apparent size (V) | 1.5′ × 1.1′ [1] |
Notable features | Seyfert galaxy |
Other designations | |
UGC 12332, Arp 298, Mrk 1514, MCG +01-58-025, PGC 70348 [1] |
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. [2]
NGC 7469 is a type I Seyfert galaxy, characterised by its bright nucleus. It is also a luminous infrared source with a powerful starburst embedded into its circumnuclear region. [3] The coexistence of a circumnuclear starburst ring and an active galactic nucleus have turned NGC 7469 into a key target for studying their relation. [4] NGC 7469 interacts with its smaller companion IC 5283, forming a pair collectively known in the Atlas of Peculiar Galaxies as Arp 298. NGC 7469 is one of the first galaxies observed by the James Webb Space Telescope. [5]
NGC 7469 is a type 1.2 Seyfert galaxy and one of the most well studied Seyfert galaxies. In 1943, this galaxy was one of six nebulae listed by American astronomer Carl K. Seyfert that showed broad emission lines in their nuclei. [6] Members of this class of objects became known as Seyfert galaxies, and they were noted to have a higher than normal surface brightness in their nuclei. NGC 7469 was also noted to have very broad hydrogen lines. [7] Type 1 Seyfert galaxies are identified as having broad emission lines and being radio-quiet active galactic nuclei (AGN) in the unified scheme suggested in the 1990s. [8] [9]
The most accepted theory for the energy source of AGNs is the presence of an accretion disk around a supermassive black hole. In the case of NGC 7469 the mass of the circumnuclear gas disk is nearly equal to that of the accretion disk. [10] NGC 7469 is believed to host a supermassive black hole whose mass is estimated to be (12.2±1.4)×106 M☉ based on broad emission-line reverberation mapping [11] or 6460000M☉ as measured based on velocity dispersion. [12] Around the black hole there is a dust torus lying at a distance of 65-87 light days, based on K-band lag times. [13]
The light curves of NGC 7469 feature variability, a phenomenon common among Seyfert galaxies, with significant variability along its spectrum. Various studies have monitored its X-ray, UV and optical spectrum for several months. A more long-term study of the variability was published in 2017, after monitoring the optical spectrum of NGC 7469 from 1996 to 2015. Maximum activity was observed in 1998, while several flare-likes events lasting 1–5 days took also place. The variability of the spectrum seems to have two periods of around 1200 and 2600 days. There were also observed time-lags, which were nearly 21 days for Hβ, 3 days for Ha, and 3 days for HeII. [14]
It has been observed in the X-ray and ultraviolet that there is an outflow of ionised gas from the region of the nucleus. The total output of the outflow is estimated to be 0.06 M☉ per year. Based on the spectrum of the outflow, it is composed of two elements, one with a velocity of 580–720 km/s and high ionisation and one with a velocity of 2300 km/s and lower ionisation. The location of the faster gas is from the space between the supermassive black hole and the inner part of the torus and it may be wind produced from the torus. [15] [16] The low velocity gas is a highly ionized, high-density absorber, located near the broad emission-line region. Its total column density is calculated to be 1020 per square centimetre. [17]
Genzel et al. detected a 1.5 arcsecond ridge of blueshifted, radially streaming gas emanating southward from the nucleus, that can also be spotted in radio waves. It could be gas outflowing from the nucleus or material channeled from the ring to the nucleus. [18] A small radio cone was also observed by Lonsdale et al.. They observed three spatially close sources in the nucleus, that may be explained as the nucleus with two radio jets in both sides emerging from the mid infrared disk. [19] [20]
Around the nucleus has been observed a ring of intense star formation. Its emission was first detected in radio waves by Ulvestad et al. in 1981 [21] and has then been observed in infrared, and optical wavelengths. [22] The ring accounts for up to two-thirds of the galaxy's bolometric luminosity (3×1011 L☉ ). The ring has a radius of 1".5 from the nucleus (500 pc). [18] The intense star formation in NGC 7469 may be a result of the interaction with IC 5283 and the presence of a small bar, however it is caused by local gravitational instabilities and not non-circular motions. [23] The star formation rate in the galaxy is estimated to be between 40 and 80 M☉/year. [24]
The ring was observed in great detail by the Hubble Space Telescope. About 30 star clusters were observed, with masses ranging from 0.5 to over 10 million M☉, fitting the definition of super star clusters. Such massive star clusters have been observed in other starburst and luminous infrared galaxies too. Further examination of the properties of the clusters revealed they group in two populations, a population of intermediate age (~9–20 Myr) and less obscured (AV ≈ 1 mag) star clusters, accounting for the 75% of the total population, and a population of young (1–3 Myr) and extinct (AV ≈ 3 mag) star clusters. The young stars account for about the one other of the mass of the ring and most of the infrared luminosity. Their location is marked by mid infrared and radio waves peaks, with the two brightest coinciding spatially with the ends of the nuclear molecular gas bar. The total stellar mass of the ring was estimated not to exceed 3.5 × 109M☉. [22]
Observations in the millimetre wavelengths produced a CO 2-1 map, which featured a partial ring or spiral arms at a radius of 1."5–2."5 (500-800 parsec at the distance of NGC 7469), with a bar-like structure connecting them to the central source. In the centre of the galaxy has been resolved in the 2.3 μm C0 2-0 band a nuclear star cluster, which measures 0."15-0."25 across. It has asymmetric shape and its age is less than 60 million years. It accounts for 20%–30% of the nuclear K-band light and about 10% of the nuclear bolometric luminosity. [4]
Aside the circumnuclear starburst ring, NGC 7469 features an inner spiral structure, about 33 arcseconds in diameter and a fainter outer ring, with a diameter of approximately 100 arcseconds. [7] In Hα imaging, a number of star producing H II regions have been observed in the north arm of NGC 7469 but none at the south one, most likely due to the interaction with IC 5283. [25]
Two supernovae have been detected in NGC 7469: SN 2000ft, and SN 2008ec (Type Ia, mag. 17.6). [26] SN 2000ft is the first radio supernova detected in the circumnuclear starburst of a luminous infrared Seyfert 1 galaxy, about 600 parsecs from its nucleus. Its evolution features characteristics of radio supernovae identified as type II supernovae. [27] A visual counterpart was detected in images by the Hubble Space Telescope taken on May 13, 2000, at visual magnitude 19.2. [28] Based on the rate of starburst activity in NGC 7469 it has been calculated that the core collapse supernova rate should be 0.8 supernova per year. However, observations of the circumnuclear ring of the galaxy in radiowaves failed to observe another radio supernova between 1998 and 2006, other than SN 2000ft. A possible reason is that most core collapse supernovae are radio quiet and cannot be detected against the galactic background emission (SN 2000ft had strong radio waves emission). [24]
NGC 7469 forms a pair with its smaller companion IC 5283, a spiral galaxy with no nuclear activity 1'4 away. The tidal interaction between the two galaxies has created a prominent tail to the northeast and enhanced star formation on the eastern side as seen with Hα imaging of IC 5283 and is likely the cause of the star formation in NGC 7469. [25] A gas bridge has been detected between the two galaxies in HI imaging and there is evidence that NGC 7469 is drawing gas from the disk of IC 5283. [29] The galaxy pair is isolated. [30]
It has been suggested that the pair is an outlying member of the Pegasus I galaxy cluster, [31] whose most prominent members are the elliptical galaxies NGC 7619, and NGC 7626. [32] However, based on redshift, they belong to a galaxy group lying behind the cluster. Other members of this group include the disk galaxies NGC 7511, NGC 7515, NGC 7529, NGC 7535, NGC 7536, NGC 7570, NGC 7580, and NGC 7591. The group may be associated with the Perseus–Pisces Supercluster. [33]
Messier 61 is an intermediate barred spiral galaxy in the Virgo Cluster of galaxies. It was first discovered by Barnaba Oriani on May 5, 1779, six days before Charles Messier discovered the same galaxy. Messier had observed it on the same night as Oriani but had mistaken it for a comet. Its distance has been estimated to be 45.61 million light years from the Milky Way Galaxy. It is a member of the M61 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.
Messier 95, also known as M95 or NGC 3351, is a barred spiral galaxy about 33 million light-years away in the zodiac constellation Leo. It was discovered by Pierre Méchain in 1781, and catalogued by compatriot Charles Messier four days later. In 2012 its most recent supernova was discovered.
NGC 4639 is a barred spiral galaxy located in the equatorial constellation of Virgo. It was discovered by German-born astronomer William Herschel on April 12, 1784. John L. E. Dreyer described it as "pretty bright, small, extended, mottled but not resolved, 12th magnitude star 1 arcmin to southeast". This is a relatively nearby galaxy, lying approximately 72 million light-years away from the Milky Way. It is a companion to NGC 4654, and the two appear to have interacted roughly 500 million years ago. NGC 4639 is a member of the Virgo Cluster.
NGC 1808 is a barred spiral galaxy located in the southern constellation of Columba, about two degrees to the south and east of Gamma Caeli. It was discovered by Scottish astronomer James Dunlop, who described it as a "faint nebula". The galaxy is a member of the NGC 1808 group, which is part of the larger Dorado Group.
NGC 7319 is a highly distorted barred spiral galaxy that is a member of the compact Stephan's Quintet group located in the constellation Pegasus, some 311 megalight-years distant from the Milky Way. The galaxy's arms, dust and gas have been highly disturbed as a result of the interaction with the other members of the Quintet. Nearly all of the neutral hydrogen has been stripped from this galaxy, most likely as a result of a collision with NGC 7320c some 100 million years ago. A pair of long, parallel tidal tails extend southward from NGC 7319 in the direction of NGC 7320c, and is undergoing star formation.
NGC 7552 is a barred spiral galaxy in the constellation Grus. It is at a distance of circa 60 million light years from Earth, which, given its apparent dimensions, means that NGC 7552 is about 75,000 light years across. It forms with three other spiral galaxies the Grus Quartet.
NGC 2782 is a peculiar spiral galaxy that formed after a galaxy merger in the constellation Lynx. The galaxy lies 75 million light years away from Earth, which means, given its apparent dimensions, that NGC 2782 is approximately 100,000 light years across. NGC 2782 has an active galactic nucleus and it is a starburst and a type 1 Seyfert galaxy. NGC 2782 is mentioned in the Atlas of Peculiar Galaxies in the category galaxies with adjacent loops.
NGC 3367 is a barred spiral galaxy located in the constellation Leo. It is located at a distance of about 120 million light years from Earth, which, given its apparent dimensions, means that NGC 3367 is about 85,000 light years across. It was discovered by William Herschel on March 19, 1784.
NGC 7130 is a spiral galaxy located in the constellation Piscis Austrinus. It is located at a distance of about 220 million light years from Earth, which, given its apparent dimensions, means that NGC 7130 is about 100,000 light years across. It was discovered by John Herschel on September 25, 1834, and discovered independently by Lewis Swift on September 17, 1897. The location of the galaxy given in the New General Catalogue was off by 30 arcminutes in declination from the location of the galaxy.
NGC 7674 is a spiral galaxy located in the constellation Pegasus. It is located at a distance of circa 350 million light years from Earth, which, given its apparent dimensions, means that NGC 7674 is about 125,000 light years across. It was discovered by John Herschel on August 16, 1830.
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 6951 is a barred spiral galaxy located in the constellation Cepheus. It is located at a distance of about 75 million light-years from Earth, which, given its apparent dimensions, means that NGC 6951 is about 100,000 light-years across. It was discovered by Jérôme Eugène Coggia in 1877 and independently by Lewis Swift in 1878.
NGC 759 is an elliptical galaxy located 230 million light-years away in the constellation Andromeda. NGC 759 was discovered by astronomer by Heinrich d'Arrest on September 17, 1865. It is a member of Abell 262.
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 2273 is a barred spiral galaxy located in the constellation Lynx. It is located at a distance of circa 95 million light years from Earth, which, given its apparent dimensions, means that NGC 2273 is about 100,000 light years across. It was discovered by Nils Dunér on September 15, 1867.
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 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.
NGC 7679 is a lenticular galaxy with a peculiar morphology in the constellation Pisces. It is located at a distance of circa 200 million light years from Earth, which, given its apparent dimensions, means that NGC 7679 is about 60,000 light years across. It was discovered by Heinrich d'Arrest on September 23, 1864. The total infrared luminosity is 1011.05 L☉, and thus it is categorised as a luminous infrared galaxy. NGC 7679 is both a starburst galaxy and a Seyfert galaxy.
NGC 5135 is a barred spiral galaxy located in the constellation Hydra. It is located at a distance of about 200 million light years from Earth. It was discovered by John Herschel on May 8, 1834. It is a Seyfert galaxy.
NGC 3786 is an intermediate spiral galaxy located 107.5 million light-years away in the northern constellation of Ursa Major. It was discovered by English astronomer John Herschel on April 10, 1831. This object appears to form a close pair with its peculiar neighbor to the north, NGC 3788. They show some indications of interaction, such as minor distortion of the disk or tidal features.