The Andromeda Galaxy is a barred spiral galaxy and is the nearest major galaxy to the Milky Way, where the Solar System resides. It was originally named the Andromeda Nebula and is cataloged as Messier 31, M31, and NGC 224. Andromeda has a diameter of about 46.56 kiloparsecs and is approximately 765 kpc from Earth. The galaxy's name stems from the area of Earth's sky in which it appears, the constellation of Andromeda, which itself is named after the princess who was the wife of Perseus in Greek mythology.
Messier 87 is a supergiant elliptical galaxy in the constellation Virgo that contains several trillion stars. One of the largest and most massive galaxies in the local universe, it has a large population of globular clusters—about 15,000 compared with the 150–200 orbiting the Milky Way—and a jet of energetic plasma that originates at the core and extends at least 1,500 parsecs, traveling at a relativistic speed. It is one of the brightest radio sources in the sky and a popular target for both amateur and professional astronomers.
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, not even 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.
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.
Omega Centauri is a globular cluster in the constellation of Centaurus that was first identified as a non-stellar object by Edmond Halley in 1677. Located at a distance of 17,090 light-years, it is the largest-known globular cluster in the Milky Way at a diameter of roughly 150 light-years. It is estimated to contain approximately 10 million stars, and a total mass equivalent to 4 million solar masses, making it the most massive-known globular cluster in the Milky Way.
Messier 60 or M60, also known as NGC 4649, is an elliptical galaxy approximately 57 million light-years away in the equatorial constellation of Virgo. Together with NGC 4647, it forms a pair known as Arp 116. Messier 60 and nearby elliptical galaxy Messier 59 were discovered by Johann Gottfried Koehler in April 1779, observing a comet in the same part of the sky. Charles Messier added both to his catalogue about three days after this.
IC 1101 is a class S0 supergiant (cD) lenticular galaxy at the center of the Abell 2029 galaxy cluster. It has an isophotal diameter at about 123.65 to 169.61 kiloparsecs. It possesses a diffuse core which is the largest known core of any galaxy to date, and also hosts a supermassive black hole that is one of the largest black holes known. The galaxy is located at 354.0 megaparsecs from Earth. The galaxy was discovered on 19 June 1790, by the British astronomer William Herschel.
NGC 4319 is a face-on barred spiral galaxy located about 77 million light years away in the constellation Draco. The morphological classification is SB(r)ab, which indicates it is a barred spiral with an inner ring structure and moderate to tightly wound arms. It is situated in physical proximity to the galaxies NGC 4291 and NGC 4386, with X-ray emissions from the intervening gap indicating NGC 4319 and NGC 4291 may be interacting. NGC 4319 has a much higher proportion of ionized hydrogen compared to the Milky Way galaxy.
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 diagram of an electron orbiting an atomic nucleus.
Hanny's Voorwerp, is a rare type of astronomical object called a quasar ionization echo. It was discovered in 2007 by Dutch schoolteacher Hanny van Arkel while she was participating as a volunteer in the Galaxy Zoo project, part of the Zooniverse group of citizen science websites. Photographically, it appears as a bright blob close to spiral galaxy IC 2497 in the constellation Leo Minor.
Mayall's Object is the result of two colliding galaxies located 500 million light years away within the constellation of Ursa Major. It was discovered by American astronomer Nicholas U. Mayall of the Lick Observatory on 13 March 1940, using the Crossley reflector. When first discovered, Mayall's Object was described as a peculiar nebula, shaped like a question mark. Originally theorized to represent a galaxy reacting with the intergalactic medium, it is now thought to represent the collision of two galaxies, resulting in a new object consisting of a ring-shaped galaxy with a tail emerging from it. It is thought that the collision between the two galaxies created a shockwave that initially drew matter into the center which then formed the ring.
NGC 1614 is the New General Catalogue identifier for a spiral galaxy in the equatorial constellation of Eridanus. It was discovered on December 29, 1885 by American astronomer Lewis Swift, who described it in a shorthand notation as: pretty faint, small, round, a little brighter middle. The nebula was then catalogued by Danish-Irish astronomer J. L. E. Drayer in 1888. When direct photography became available, it was noted that this galaxy displayed some conspicuous peculiarities. American astronomer Halton Arp included it in his 1966 Atlas of Peculiar Galaxies. In 1971, Swiss astronomer Fritz Zwicky described it as a "blue post-eruptive galaxy, compact patchy core, spiral plumes, long blue jet SSW".
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 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.
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.
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 3585 is an elliptical or a lenticular galaxy located in the constellation Hydra. It is located at a distance of circa 60 million light-years from Earth, which, given its apparent dimensions, means that NGC 3585 is about 80,000 light years across. It was discovered by William Herschel on December 9, 1784.
IC 1459 is an elliptical galaxy located in the constellation Grus. It is located at a distance of circa 85 million light-years from Earth, which, given its apparent dimensions, means that IC 1459 is about 130,000 light-years across. It was discovered by Edward Emerson Barnard in 1892.
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 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.
