NGC 6240, also known as the Starfish Galaxy, is a nearby ultraluminous infrared galaxy (ULIRG) in the constellation Ophiuchus. The galaxy is the remnant of a merger between three smaller galaxies. The collision between the three progenitor galaxies has resulted in a single, larger galaxy with three distinct nuclei and a highly disturbed structure, including faint extensions and loops.
The Chandra X-ray Observatory (CXO), previously known as the Advanced X-ray Astrophysics Facility (AXAF), is a Flagship-class space telescope launched aboard the Space ShuttleColumbia during STS-93 by NASA on July 23, 1999. Chandra was sensitive to X-ray sources 100 times fainter than any previous X-ray telescope, enabled by the high angular resolution of its mirrors. Since the Earth's atmosphere absorbs the vast majority of X-rays, they are not detectable from Earth-based telescopes; therefore space-based telescopes are required to make these observations. Chandra is an Earth satellite in a 64-hour orbit, and its mission is ongoing as of 2024.
Centaurus A is a galaxy in the constellation of Centaurus. It was discovered in 1826 by Scottish astronomer James Dunlop from his home in Parramatta, in New South Wales, Australia. There is considerable debate in the literature regarding the galaxy's fundamental properties such as its Hubble type and distance. NGC 5128 is one of the closest radio galaxies to Earth, so its active galactic nucleus has been extensively studied by professional astronomers. The galaxy is also the fifth-brightest in the sky, making it an ideal amateur astronomy target. It is only visible from the southern hemisphere and low northern latitudes.
The Centaurus Cluster (A3526) is a cluster of hundreds of galaxies, located approximately 170 million light-years away in the Centaurus constellation. The brightest member galaxy is the elliptical galaxy NGC 4696 (~11m). The Centaurus cluster shares its supercluster, the Hydra–Centaurus Supercluster, with IC4329 Cluster and Hydra Cluster.
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 3115 is a field lenticular (S0) galaxy in the constellation Sextans. The galaxy was discovered by William Herschel on February 22, 1787. At about 32 million light-years away from Earth, it is several times bigger than the Milky Way. It is a lenticular (S0) galaxy because it contains a disk and a central bulge of stars, but without a detectable spiral pattern. NGC 3115 is seen almost exactly edge-on, but was nevertheless mis-classified as elliptical. There is some speculation that NGC 3115, in its youth, was a quasar.
The Perseus cluster is a cluster of galaxies in the constellation Perseus. It has a recession speed of 5,366 km/s and a diameter of 863′. It is one of the most massive objects in the known universe, containing thousands of galaxies immersed in a vast cloud of multimillion-degree gas.
Abell 400 is a galaxy cluster which contains the galaxy NGC 1128 with two supermassive black holes spiraling towards merger.
3C 75 is a binary black hole system in the dumbbell-shaped galaxy NGC 1128 in the galaxy cluster Abell 400. It has four relativistic jets, two coming from each accreting supermassive black hole. It is travelling at 1200 kilometers per second, causing the jets to be swept back. 3C 75 may be X-ray source 2A 0252+060.
Astrophysical X-ray sources are astronomical objects with physical properties which result in the emission of X-rays.
The type-cD galaxy is a galaxy morphology classification, a subtype of type-D giant elliptical galaxy. Characterized by a large halo of stars, they can be found near the centres of some rich galaxy clusters. They are also known as supergiant ellipticals or central dominant galaxies.
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. One of the many starburst spiral arms contains an intermediate mass black hole with 50,000 times the mass of the Sun, named NGC 2276-3c. NGC 2276-3c has produced two jets: a large-scale radio jet, approximately 2,000 light years long, and an "inner jet" about 6 light years long. The galaxy shows an enhanced rate of star formation that may have been triggered by a collision with a dwarf galaxy, or by the gravitational interaction with its neighbor compressing gas and dust.
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 1271 is a compact elliptical or lenticular galaxy located about 250 million light-years away in the constellation Perseus. The galaxy was discovered by astronomer Guillaume Bigourdan on November 14, 1884. NGC 1271 is a member of the Perseus Cluster and has a nuclear dust disk in its center. It also has an edge-on, intermediate-scale disk and has a central bulge. Like NGC 1277, NGC 1271 is a candidate "relic galaxy".
NGC 1281 is a compact elliptical galaxy located about 200 million light-years away in the constellation Perseus. NGC 1281 was discovered by astronomer John Dreyer on December 12, 1876. It is a member of the Perseus 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 541 is a lenticular galaxy located in the constellation Cetus. It is located at a distance of circa 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 545 is a lenticular galaxy located in the constellation Cetus. It is located at a distance of circa 250 million light years from Earth, which, given its apparent dimensions, means that NGC 545 is about 180,000 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 547 is an elliptical galaxy and radio galaxy located in the constellation Cetus. It is located at a distance of circa 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 7720 is an elliptical galaxy located in the constellation Pegasus. It is located at a distance of about 380 million light years from Earth, which, given its apparent dimensions, means that NGC 7720 is about 180,000 light years across. NGC 7720 is the main galaxy of Abell 2634 galaxy cluster and is a radio galaxy. It was discovered by William Herschel on September 10, 1784.
