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Palomar 5
Palomar 5 is a globular cluster and a member of the Palomar Globular Clusters group. It was discovered by Walter Baade in 1950, and independently found again by Albert George Wilson in 1955. After the initial name of Serpens, it was subsequently catalogued as Palomar 5. There is a process of disruption acting on this cluster because of the gravitation of the Milky Way – in fact there are many stars leaving this cluster in the form of a stellar stream. The stream has a mass of 5000 solar masses and is 30,000 light years long. The cluster is currently from the Galactic Center. It shows a noticeable amount of flattening, with an aspect ratio of between its semimajor axis and semiminor axis. See also * List of globular clusters * List of stellar streams This is a list of stellar streams. A stellar stream is an association of stars orbiting a galaxy that was once a globular cluster or dwarf galaxy that has now been torn apart and stretched out along its orbit by tidal forces ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
J2000
In astronomy, an epoch or reference epoch is a instant, moment in time used as a reference point for some time-varying astronomical quantity. It is useful for the celestial coordinates or orbital elements of a Astronomical object, celestial body, as they are subject to Perturbation (astronomy), perturbations and vary with time. These time-varying astronomical quantities might include, for example, the mean longitude or mean anomaly of a body, the node of its orbit relative to a reference plane, the direction of the apogee or Perihelion and aphelion, aphelion of its orbit, or the size of the major axis of its orbit. The main use of astronomical quantities specified in this way is to calculate other relevant parameters of motion, in order to predict future positions and velocities. The applied tools of the disciplines of celestial mechanics or its subfield orbital mechanics (for predicting orbital paths and positions for bodies in motion under the gravitational effects of other bodi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Serpens
Serpens ( grc, , , the Serpent) is a constellation in the northern celestial hemisphere. One of the 48 constellations listed by the 2nd-century astronomer Ptolemy, it remains one of the 88 modern constellations designated by the International Astronomical Union. It is unique among the modern constellations in being split into two non-contiguous parts, Serpens Caput (Serpent Head) to the west and Serpens Cauda (Serpent Tail) to the east. Between these two halves lies the constellation of Ophiuchus, the "Serpent-Bearer". In figurative representations, the body of the serpent is represented as passing behind Ophiuchus between Mu Serpentis in ''Serpens Caput'' and Nu Serpentis in ''Serpens Cauda''. The brightest star in Serpens is the red giant star Alpha Serpentis, or Unukalhai, in Serpens Caput, with an apparent magnitude of 2.63. Also located in Serpens Caput are the naked-eye globular cluster Messier 5 and the naked-eye variables R Serpentis and Tau4 Serpentis. Notable ext ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gigayear
A billion years or giga-annum (109 years) is a unit of time on the petasecond scale, more precisely equal to seconds (or simply 1,000,000,000 years). It is sometimes abbreviated Gy, Ga ("giga-annum"), Byr and variants. The abbreviations Gya or bya are for "billion years ago", i.e. billion years before present. The terms are used in geology, paleontology, geophysics, astronomy, and physical cosmology. The prefix giga- is preferred to billion- to avoid confusion in the long and short scales over the meaning of billion; the postfix annum may be further qualified for precision as a sidereal year or Julian year: :1 Gaj = s, :1 Gas = s (epoch J2000.0). :1 Gas = y Byr was formerly used in English-language geology and astronomy as a unit of one billion years. Subsequently, the term gigaannum (Ga) has increased in usage, with Gy or Gyr still sometimes used in English-language works (at the risk of confusion with Gy as abbreviation for the gray, a u ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Uppsala General Catalogue
The Uppsala General Catalogue of Galaxies (UGC) is a catalogue of 12,921 galaxies visible from the northern hemisphere. It was first published in 1973. The catalogue includes essentially all galaxies north of declination -02°30' and to a limiting diameter of 1.0 arcminute or to a limiting apparent magnitude of 14.5. The primary source of data is the blue prints of the Palomar Observatory Sky Survey (POSS). It also includes galaxies smaller than 1.0 arcminute in diameter but brighter than 14.5 magnitude from the Catalogue of Galaxies and of Clusters of Galaxies (CGCG). The catalogue contains descriptions of the galaxies and their surrounding areas, plus conventional system classifications and position angles for flattened galaxies. Galaxy diameters are included and the classifications and descriptions are given in such a way as to provide as accurate an account as possible of the appearance of the galaxies on the prints. The accuracy of coordinates is only what is necessary for ide ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Globular Cluster
A globular cluster is a spheroidal conglomeration of stars. Globular clusters are bound together by gravity, with a higher concentration of stars towards their centers. They can contain anywhere from tens of thousands to many millions of member stars. Their name is derived from Latin (small sphere). Globular clusters are occasionally known simply as "globulars". Although one globular cluster, Omega Centauri, was observed in antiquity and long thought to be a star, recognition of the clusters' true nature came with the advent of telescopes in the 17th century. In early telescopic observations globular clusters appeared as fuzzy blobs, leading French astronomer Charles Messier to include many of them in his catalog of astronomical objects that he thought could be mistaken for comets. Using larger telescopes, 18th-century astronomers recognized that globular clusters are groups of many individual stars. Early in the 20th century the distribution of globular clusters in the sky w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Walter Baade
Wilhelm Heinrich Walter Baade (March 24, 1893 – June 25, 1960) was a German astronomer who worked in the United States from 1931 to 1959. Biography The son of a teacher, Baade finished school in 1912. He then studied maths, physics and astronomy at the universities of Münster and Göttingen. After receiving his PhD in 1919, Baade worked at Hamburg Observatory at Bergedorf from 1919 to 1931. There in 1920 he discovered 944 Hidalgo, the first of a class of minor planets now called Centaurs which cross the orbits of giant planets. He worked at Mount Wilson Observatory from 1931 to 1958. There, during World War II, he took advantage of wartime blackout conditions (which reduced light pollution), to resolve stars in the center of the Andromeda Galaxy for the first time. These observations led him to define distinct "populations" for stars (Population I and Population II). The same observations led him to discover that there are two types of Cepheid variable stars. Using this disc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Albert George Wilson
Albert George Wilson (July 28, 1918 – August 27, 2012) was an American astronomer and a discoverer of minor planets. He was born in Houston, Texas. He received his Ph.D. in mathematics from Caltech in 1947; his thesis title was ''Axially Symmetric Thermal Stresses in a Semi-Infinite Solid'' advised by Harry Bateman. In 1949 he accepted a job at Palomar Observatory, and led the Palomar Sky Survey. In 1953 he became assistant director of Lowell Observatory, and served as director from 1954 to 1957. He later worked at Rand Corporation The RAND Corporation (from the phrase "research and development") is an American nonprofit global policy think tank created in 1948 by Douglas Aircraft Company to offer research and analysis to the United States Armed Forces. It is financed ... and other private sector positions. In 1962 he became founding editor of the astronomical magazine ''Icarus (journal), Icarus''. In 1966, he accepted the position of associate director of McDonne ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Milky Way
The Milky Way is the galaxy that includes our Solar System, with the name describing the galaxy's appearance from Earth: a hazy band of light seen in the night sky formed from stars that cannot be individually distinguished by the naked eye. The term ''Milky Way'' is a translation of the Latin ', from the Greek ('), meaning "milky circle". From Earth, the Milky Way appears as a band because its disk-shaped structure is viewed from within. Galileo Galilei first resolved the band of light into individual stars with his telescope in 1610. Until the early 1920s, most astronomers thought that the Milky Way contained all the stars in the Universe. Following the 1920 Great Debate between the astronomers Harlow Shapley and Heber Curtis, observations by Edwin Hubble showed that the Milky Way is just one of many galaxies. The Milky Way is a barred spiral galaxy with an estimated D25 isophotal diameter of , but only about 1,000 light years thick at the spiral arms (more at the bulg ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stellar Stream
In astronomy, stellar kinematics is the observational study or measurement of the kinematics or motions of stars through space. Stellar kinematics encompasses the measurement of stellar velocities in the Milky Way and its satellites as well as the internal kinematics of more distant galaxies. Measurement of the kinematics of stars in different subcomponents of the Milky Way including the thin disk, the thick disk, the bulge, and the stellar halo provides important information about the formation and evolutionary history of our Galaxy. Kinematic measurements can also identify exotic phenomena such as hypervelocity stars escaping from the Milky Way, which are interpreted as the result of gravitational encounters of binary stars with the supermassive black hole at the Galactic Center. Stellar kinematics is related to but distinct from the subject of stellar dynamics, which involves the theoretical study or modeling of the motions of stars under the influence of gravity. Stellar-dyn ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Galactic Center
The Galactic Center or Galactic Centre is the rotational center, the barycenter, of the Milky Way galaxy. Its central massive object is a supermassive black hole of about 4 million solar masses, which is called Sagittarius A*, a compact radio source which is almost exactly at the galactic rotational center. The Galactic Center is approximately away from Earth in the direction of the constellations Sagittarius, Ophiuchus, and Scorpius, where the Milky Way appears brightest, visually close to the Butterfly Cluster (M6) or the star Shaula, south to the Pipe Nebula. There are around 10 million stars within one parsec of the Galactic Center, dominated by red giants, with a significant population of massive supergiants and Wolf–Rayet stars from star formation in the region around 1 million years ago. The core stars are a small part within the much wider galactic bulge. Discovery Because of interstellar dust along the line of sight, the Galactic Center cannot be studied at v ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
List Of Globular Clusters
This is a list of globular clusters. The apparent magnitude does not include an extinction correction. Milky Way These are globular clusters within the halo of the Milky Way galaxy. The diameter is in minutes of arc as seen from Earth. For reference, the J2000 epoch celestial coordinates of the Galactic Center are right ascension , declination . A high proportion of globular clusters are located in the Ophiuchus and Sagittarius constellations, both of which lie in the direction of the galactic core. Local Group See also * Lists of astronomical objects References Galactic Globular Clusters Database from Marco Castellani (Astronomical Observatory of Rome, Italy) VizieR VII/202 – Globular Clusters in the Milky Way (Harris, 1997) Richard Powell Andrés Valencia and Arnaldo Arnal * Djorgovski, S., and Meylan, G. 1993, in "Structure and Dynamics of Globular Clusters", ASP Conf. Ser. vol. 50, p. 32 External links LMC Clusters database University of Cambridge. * ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
