| NGC 7727 | |
|---|---|
 NGC 7727 by the Gemini Observatory | |
| Observation data (J2000 epoch) | |
| Constellation | Aquarius |
| Right ascension | 23h 39.9m [1] |
| Declination | −12° 17′ 34″ [1] |
| Apparent magnitude (V) | 11.5 [1] |
| Characteristics | |
| Type | SAB(s)a pec [1] |
| Apparent size (V) | 4.7′ × 3.5′ [1] |
| Other designations | |
| PGC 72060, Arp 222 | |
NGC 7727 is a peculiar galaxy in the constellation Aquarius. It harbors two galactic nuclei, each containing a supermassive black hole, separated 1,600 light years apart. [2]
This object is located at a distance of 23.3 megaparsecs (76 million light years) from the Milky Way [1] and has a peculiar aspect, with several plumes and streams of irregular shape that explains its inclusion on Halton C. Arp's Atlas of Peculiar Galaxies with the number 222, being classified as a "Galaxy with amorphous spiral arms".
In all likelihood, this system is the product of the merger of two previous spiral galaxies that took place 1 billion years ago, [3] with the aforementioned stellar plumes and streams being the remnants of the disks of the two galaxies that collided to form this object.
Two starlike objects can be seen in NGC 7727's center, at least one of them likely being the former core of one of those two spiral galaxies. [4] In addition to this, 23 objects – candidates to be young globular clusters formed in the collision – can be found in this system. [3]
NGC 7727 is very similar to NGC 7252, another galaxy product of the collision and merging of two former spiral galaxies, in the same constellation. However it has far less gas (neutral hydrogen and molecular hydrogen) than the latter. [5]
NGC 7727's most likely fate is to become an elliptical galaxy in the future, with very little interstellar dust and star formation. [6]
In November 2021, scientists announced the discovery of a pair of supermassive black holes in NGC 7727, detected with the Very Large Telescope's multi-unit spectroscopic explorer (MUSE) at the European Southern Observatory. The black holes have masses of 154 and 6.3 million solar masses, and are separated 1,600 light years apart. The pair are among the closest confirmed supermassive black holes to Earth at about 89 million light years away. Although the pair are separated closely enough to gravitationally influence each other, the smaller black hole is not bound in orbit around the larger black hole due to the surrounding mass of the NGC 7727 core region. The black holes will eventually merge in the next 250 million years, producing powerful, low-frequency gravitational waves in the process. [7] [2]
NGC 6240, also known as the Starfish Galaxy, is a nearby ultraluminous infrared galaxy (ULIRG) in the constellation Ophiuchus. It was discovered by French astronomer Édouard Stephan on 12 July 1871.
A supermassive black hole is the largest type of black hole, with its mass being on the order of hundreds of thousands, or millions to billions, of times the mass of the Sun (M☉). Black holes are a class of astronomical objects that have undergone gravitational collapse, leaving behind spheroidal regions of space from which nothing can escape, including light. Observational evidence indicates that almost every large galaxy has a supermassive black hole at its center. For example, the Milky Way galaxy has a supermassive black hole at its center, corresponding to the radio source Sagittarius A*. Accretion of interstellar gas onto supermassive black holes is the process responsible for powering active galactic nuclei (AGNs) and quasars.
NGC 5195 is a dwarf galaxy that is interacting with the Whirlpool Galaxy. Both galaxies are located approximately 25 million light-years away in the constellation Canes Venatici. Together, the two galaxies are one of the most famous interacting galaxy pairs.
Interacting galaxies are galaxies whose gravitational fields result in a disturbance of one another. An example of a minor interaction is a satellite galaxy disturbing the primary galaxy's spiral arms. An example of a major interaction is a galactic collision, which may lead to a galaxy merger.
NGC 1097 is a barred spiral galaxy about 45 million light years away in the constellation Fornax. It was discovered by William Herschel on 9 October 1790. It is a severely interacting galaxy with obvious tidal debris and distortions caused by interaction with the companion galaxy NGC 1097A.
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 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 (M☉) 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 Eyes Galaxies are a pair of galaxies about 52 million light-years away in the constellation Virgo. The pair are members of the string of galaxies known as Markarian's Chain.
NGC 5005, also known as Caldwell 29, is an inclined spiral galaxy in the constellation Canes Venatici. The galaxy has a relatively bright nucleus and a bright disk that contains multiple dust lanes. The galaxy's high surface brightness makes it an object that is visible to amateur astronomers using large amateur telescopes.
NGC 7252 is a peculiar galaxy resulting from an interaction between two galaxies that started a billion years ago. It is located 220 million light years away in the constellation Aquarius. It is also called Atoms for Peace Galaxy, a nickname which comes from its loop-like structure, made of stars, that resembles a classic diagram of an electron orbiting an atomic nucleus.
NGC 7314 is a spiral galaxy located in the southern constellation of Piscis Austrinus. It was discovered by English astronomer John Herschel on July 29, 1834. This is a nearby Seyfert (active) galaxy, located at a distance of approximately 54.6 megalight-years from the Milky Way. Since it appears to have detached spiral arm segments, it was listed in Halton Arp's Atlas of Peculiar Galaxies.
Arp 87 is a pair of interacting galaxies, NGC 3808A and NGC 3808B. They are situated in the Leo constellation. NGC 3808A, the brighter, is a peculiar spiral galaxy, while NGC 3808B is an irregular galaxy.
NGC 2276 is an intermediate spiral galaxy in the constellation Cepheus. The galaxy lies 120 million light-years away from Earth. NGC 2276 has an asymmetrical appearance, most likely caused by gravitational interactions with its neighbor, elliptical galaxy NGC 2300. NGC 2276 is traveling with an orbital velocity of about 968 km/s due to its neighbor. Trailing NGC 2276 is a long tail of interstellar medium about 300,000 light-years long, formed by ram pressure stripping.
NGC 3642 is a spiral galaxy in the constellation Ursa Major. The galaxy has a low-ionization nuclear emission-line region. It is located at a distance of circa 30 million light years from Earth, which, given its apparent dimensions, means that NGC 3642 is about 50,000 light years across. The galaxy is characterised by an outer pseudoring, which was probably formed after the accretion of a gas rich dwarf galaxy.
NGC 4660 is an elliptical galaxy located about 63 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 2936, also known as the Penguin Galaxy or the Porpoise Galaxy, is an interacting spiral galaxy located at a distance of 326 million light years, in the constellation Hydra. NGC 2936 is interacting with elliptical galaxy NGC 2937, located just beneath it. They were both discovered by Albert Marth on Mar 3, 1864. To some astronomers, the galaxy looks like a penguin or a porpoise. NGC 2936, NGC 2937, and PGC 1237172 are included in the Atlas of Peculiar Galaxies as Arp 142 in the category "Galaxy triplet".
NGC 541 is a lenticular galaxy located in the constellation Cetus. It is located at a distance of about 230 million light years from Earth, which, given its apparent dimensions, means that NGC 541 is about 130,000 light years across. It was discovered by Heinrich d'Arrest on October 30, 1864. It is a member of the Abell 194 galaxy cluster and is included in the Atlas of Peculiar Galaxies in the category galaxies with nearby fragments. NGC 541 is a radio galaxy of Fanaroff–Riley class I, also known as 3C 40A.
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.
PKS 2131-021 is a quasar and a BL Lacerate object, producing an astrophysical jet. lt is located in the constellation Aquarius and classified as a blazar, a type of active galactic nucleus whose relativistic jet points in the direction towards Earth.
NGC 3758 known as the Owl Galaxy, is a type Sb spiral galaxy in the constellation of Leo. It is located 447 million light-years from the Solar System and an approximate diameter of 70,000 light-years. NGC 3758 was discovered by Ralph Copeland on March 18, 1874, but also independently discovered by Edouard Stephan ten years later.
Media related to NGC 7727 at Wikimedia Commons