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Cygnus OB2-8A
Cygnus OB2 #8A is a double-lined spectroscopic binary located near the centre of the Cygnus OB2 association located 5,500 light years away. Discovery Until 1951 Cyg OB2 #8 had been known only as an anonymous catalogue entry in the Bonner Durchmusterung. Then it was identified as one of several highly luminous hot stars close together in Cygnus. Despite being commonly referred to as Schulte #8A, the number 8 was first published in an earlier paper. Schulte identified the grouping as a massive stellar association and split star #8 into four components, including #8A. System The Cygnus OB2 #8A system contains two massive luminous O class stars in a 21.9 day orbit. The primary is a supergiant and the secondary is a giant star. The two stars are not thought to be exchanging mass and their luminosity classes match the main sequence turnoff The turnoff point for a star refers to the point on the Hertzsprung-Russell diagram where it leaves the main sequence after its ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bica2 HST
Bica may refer to: * Bica (coffee), a type of coffee beverage originally from Portugal * Bica, Cluj, one of 6 villages comprising the Mănăstireni commune in Cluj County, Romania * Bica-Q, a trade name of the antiandrogen bicalutamide * Fazenda da Bica, a region of Rio de Janeiro, Brazil * Quinta da Bica, a ''quinta'' (estate) near Seia, Beira region, Portugal * Bicalutamide, a drug used to treat prostate cancer and in feminizing hormone therapy People * Bica (footballer) (Marcus Di Giuseppe, born 1972), Brazilian footballer * Camillo Mac Bica (born 1947), American philosopher, poet, activist, and author * Carlos Bica (active from 1998), Portuguese jazz bassist * Sergio Bica (born 1983), Uruguayan footballer * Adrian Bică Bădan (born 1988), Romanian footballer BICA * Bahamas Institute of Chartered Accountants, a professional association * Banque Internationale pour la Centrafrique, a bank * BICA Honduras, a non-profit environmental organization in Honduras * Biological ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
1RXS
1RXS is an acronym which is the prefix used for the First ROSAT X-ray Survey (1st ROSAT X-ray Survey). This is a catalogue of astronomical objects that were visible in the X-ray spectrum from the ROSAT satellite, in the field of X-ray astronomy. Examinations of 1RXS has shown that many sources can be identified, such as old neutron stars, while other entries are "intriguing", according to one researcher. See also *1RXS J160929.1−210524 1RXS J160929.1−210524 (also known as GSC 6213-1358 or PZ99 J160930.3−210459) is a pre-main-sequence star approximately 456 light-years away in the constellation of Scorpius. The star was identified as a member of the Upper Scorpius su ..., example References External links Catalog site Astronomical surveys X-ray astronomy ROSAT objects {{spacecraft-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Astronomical X-ray Sources
Astrophysical X-ray sources are astronomical objects with physical properties which result in the emission of X-rays. Several types of astrophysical objects emit X-rays. They include galaxy clusters, black holes in active galactic nuclei (AGN), galactic objects such as supernova remnants, stars, and binary stars containing a white dwarf (cataclysmic variable stars and super soft X-ray sources), neutron star or black hole (X-ray binaries). Some Solar System bodies emit X-rays, the most notable being the Moon, although most of the X-ray brightness of the Moon arises from reflected solar X-rays. Furthermore, celestial entities in space are discussed as celestial X-ray sources. The origin of all observed astronomical X-ray sources is in, near to, or associated with a coronal cloud or gas at coronal cloud temperatures for however long or brief a period. A combination of many unresolved X-ray sources is thought to produce the observed X-ray background. The X-ray continuum can arise f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Emission-line Stars
A spectral line is a dark or bright line in an otherwise uniform and continuous spectrum, resulting from emission or absorption of light in a narrow frequency range, compared with the nearby frequencies. Spectral lines are often used to identify atoms and molecules. These "fingerprints" can be compared to the previously collected ones of atoms and molecules, and are thus used to identify the atomic and molecular components of stars and planets, which would otherwise be impossible. Types of line spectra Spectral lines are the result of interaction between a quantum system (usually atoms, but sometimes molecules or atomic nuclei) and a single photon. When a photon has about the right amount of energy (which is connected to its frequency) to allow a change in the energy state of the system (in the case of an atom this is usually an electron changing orbitals), the photon is absorbed. Then the energy will be spontaneously re-emitted, either as one photon at the same frequency ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Main Sequence Turnoff
The turnoff point for a star refers to the point on the Hertzsprung-Russell diagram where it leaves the main sequence after its main fuel is exhaustedthe main sequence turnoff. By plotting the turnoff points of individual stars in a star cluster one can estimate the cluster's age. Stars with no turnoff point Red dwarfs, also referred to as classM stars, are stars of 0.08–0.40 solar masses. They have sufficient mass to sustain hydrogen-to-helium fusion via the proton–proton chain reaction, but they do not have sufficient mass to create the temperatures and pressures necessary to fuse helium into carbon, nitrogen or oxygen (see CNO cycle). However, all their hydrogen is available for fusion, and low temperature and pressure means a lifetime measured in trillions of years. For example, the lifespan of a star of 0.1 solar masses is six trillion years. This lifespan greatly exceeds the current age of the universe, therefore all red dwarfs are main sequence stars. Even though extr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Giant Star
A giant star is a star with substantially larger radius and luminosity than a main sequence, main-sequence (or ''dwarf'') star of the same effective temperature, surface temperature.Giant star, entry in ''Astronomy Encyclopedia'', ed. Patrick Moore, New York: Oxford University Press, 2002. . They lie above the main sequence (luminosity class V in the Spectral classification#Yerkes spectral classification, Yerkes spectral classification) on the Hertzsprung–Russell diagram and correspond to luminosity classes II and III.giant, entry in ''The Facts on File Dictionary of Astronomy'', ed. John Daintith and William Gould, New York: Facts On File, Inc., 5th ed., 2006. . The terms ''giant'' and ''dwarf'' were coined for stars of quite different luminosity despite similar temperature or spectral type by Ejnar Hertzsprung about 1905. Giant stars have radii up to a few hundred times the solar radii, Sun and luminosities between 10 and a few thousand times that of the Sun. Stars still mo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Supergiant
Supergiants are among the most massive and most luminous stars. Supergiant stars occupy the top region of the Hertzsprung–Russell diagram with absolute visual magnitudes between about −3 and −8. The temperature range of supergiant stars spans from about 3,400 K to over 20,000 K. Definition The title supergiant, as applied to a star, does not have a single concrete definition. The term ''giant star'' was first coined by Hertzsprung when it became apparent that the majority of stars fell into two distinct regions of the Hertzsprung–Russell diagram. One region contained larger and more luminous stars of spectral types A to M and received the name ''giant''. Subsequently, as they lacked any measurable parallax, it became apparent that some of these stars were significantly larger and more luminous than the bulk, and the term ''super-giant'' arose, quickly adopted as ''supergiant''. Spectral luminosity class Supergiant stars can be identified on the basis of thei ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stellar Association
A stellar association is a very loose star cluster, looser than both open clusters and globular clusters. Stellar associations will normally contain from 10 to 100 or more stars. The stars share a common origin, but have become gravitationally unbound and are still moving together through space. Associations are primarily identified by their common movement vectors and ages. Identification by chemical composition is also used to factor in association memberships. Stellar associations were first discovered by the Soviet Armenian astronomer Victor Ambartsumian in 1947. The conventional name for an association uses the names or abbreviations of the constellation (or constellations) in which they are located; the association type, and, sometimes, a numerical identifier. Types Victor Ambartsumian first categorized stellar associations into two groups, OB and T, based on the properties of their stars. A third category, R, was later suggested by Sidney van den Bergh for associations th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spectroscopic Binary
A binary star is a system of two star, stars that are gravity, gravitationally bound to and in orbit around each other. Binary stars in the night sky that are seen as a single object to the naked eye are often resolved using a telescope as separate stars, in which case they are called ''visual binaries''. Many visual binaries have long orbital periods of several centuries or millennia and therefore have orbits which are uncertain or poorly known. They may also be detected by indirect techniques, such as spectroscopy (''spectroscopic binaries'') or astrometry (''astrometric binaries''). If a binary star happens to orbit in a plane along our line of sight, its components will eclipse and transit (astronomy), transit each other; these pairs are called ''eclipsing binaries'', or, together with other binaries that change brightness as they orbit, ''photometric binaries''. If components in binary star systems are close enough they can gravitationally distort their mutual outer stella ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Guide Star Catalog
The Guide Star Catalog (GSC), also known as the ''Hubble Space Telescope, Guide Catalog'' (''HSTGC''), is a star catalog compiled to support the Hubble Space Telescope with targeting off-axis stars. GSC-I contained approximately 20,000,000 stars with apparent magnitudes of 6 to 15. GSC-II contains 945,592,683 stars out to magnitude 21. As far as possible, binary stars and non-stellar objects have been excluded or flagged as not meeting the requirements of Fine Guidance Sensors. This is the first full sky star catalog created specifically for navigation in outer space. History Version 1.0 The first version of this catalog was published in 1989. The first catalog was created by digitizing photographic plates produced by the Palomar Schmidt Quick-V survey for the northern hemisphere and the UK Schmidt SERC-J survey for the southern hemisphere. This catalog contains objects in the magnitude range 7-16 and the classification was biased to prevent the use of a non-stellar object as a g ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Catalog Of Stellar Identification
The Catalog of Stellar Identifications (CSI) is a star catalog which was constructed to facilitate cross-referencing between different star catalogs. It contains designations and basic data for, as of 1983, approximately 440,000 stars, and was created by merging the Smithsonian Astrophysical Observatory Star Catalog, the Henry Draper Catalogue, the AGK2/3, the Cape Photographic Catalogue, the Cape Zone Catalogue, the Yale Zone Catalogue, the Cape Catalogue of Faint Stars, and the Boss General Catalogue. It contains stellar coordinates, magnitudes, spectral types, proper motions, and cross-references to designations in the previously mentioned catalogs. It also gives cross-references to many other catalogues, such as the Index Catalogue of Visual Double Stars, which have been linked to the CSI. The CSI eventually became part of the SIMBAD SIMBAD (the Set of Identifications, Measurements and Bibliography for Astronomical Data) is an astronomical database of objects beyond ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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