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Xi Ophiuchi
ξ Oph, Latinized as Xi Ophiuchi, is a visual binary star system in the equatorial constellation of Ophiuchus. It has a yellow-white hue and is faintly visible to the naked eye with a combined apparent visual magnitude of 4.39. The system is located approximately away from the Sun based on parallax, but is drifting closer with a radial velocity of -9 km/s. The magnitude 4.40 primary, designated component A, is an ordinary F-type main-sequence star with a stellar classification of F2V. It is 916 million years old and is rotating with a projected rotational velocity of 20 km/s. The star has 1.3 times the mass of the Sun and 1.6 times the Sun's radius. It is radiating 4.4 times the luminosity of the Sun from its photosphere at an effective temperature of 6,611 K. The system is a source of X-ray emission. The orbiting companion, component B, is a magnitude 8.9 star at an angular separation of along a position angle of 26° from the primary, as of 2016 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ophiuchus (constellation)
Ophiuchus () is a large constellation straddling the celestial equator. Its name comes from the Ancient Greek (), meaning "serpent-bearer", and it is commonly represented as a man grasping a snake. The serpent is represented by the constellation Serpens. Ophiuchus was one of the 48 constellations listed by the 2nd-century astronomer Ptolemy, and it remains one of the 88 modern constellations. An old alternative name for the constellation was Serpentarius. Location Ophiuchus lies between Aquila, Serpens, Scorpius, Sagittarius, and Hercules, northwest of the center of the Milky Way. The southern part lies between Scorpius to the west and Sagittarius to the east. In the northern hemisphere, it is best visible in summer. It is opposite of Orion. Ophiuchus is depicted as a man grasping a serpent; the interposition of his body divides the snake constellation Serpens into two parts, Serpens Caput and Serpens Cauda. Ophiuchus straddles the equator with the majority ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Angular Separation
Angular distance or angular separation is the measure of the angle between the orientation of two straight lines, rays, or vectors in three-dimensional space, or the central angle subtended by the radii through two points on a sphere. When the rays are lines of sight from an observer to two points in space, it is known as the apparent distance or apparent separation. Angular distance appears in mathematics (in particular geometry and trigonometry) and all natural sciences (e.g., kinematics, astronomy, and geophysics). In the classical mechanics of rotating objects, it appears alongside angular velocity, angular acceleration, angular momentum, moment of inertia and torque. Use The term ''angular distance'' (or ''separation'') is technically synonymous with ''angle'' itself, but is meant to suggest the linear distance between objects (for instance, a pair of stars observed from Earth). Measurement Since the angular distance (or separation) is conceptually identical to an ang ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ophiuchus
Ophiuchus () is a large constellation straddling the celestial equator. Its name comes from the Ancient Greek (), meaning "serpent-bearer", and it is commonly represented as a man grasping a snake. The serpent is represented by the constellation Serpens. Ophiuchus was one of the 48 constellations listed by the 2nd-century astronomer Ptolemy, and it remains one of the IAU designated constellations, 88 modern constellations. An old alternative name for the constellation was Serpentarius. Location Ophiuchus lies between Aquila (constellation), Aquila, Serpens, Scorpius, Sagittarius (constellation), Sagittarius, and Hercules (constellation), Hercules, northwest of the center of the Milky Way. The southern part lies between Scorpius to the west and Sagittarius (constellation), Sagittarius to the east. In the northern hemisphere, it is best visible in summer. It is opposite of Orion (constellation), Orion. Ophiuchus is depicted as a man grasping a Serpens, serpent; the int ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Binary Stars
A binary star or binary star system is a system of two stars that are 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 as separate stars using a telescope, 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 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 each other's outer stellar atmospheres. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
F-type Main-sequence Stars
An F-type main-sequence star (F V) is a main-sequence, hydrogen-fusing star of spectral type F and luminosity class V. These stars have from 1.0 to 1.4 times the mass of the Sun and surface temperatures between 6,000 and 7,600 K.Tables VII and VIII. This temperature range gives the F-type stars a whitish hue when observed by the atmosphere. Because a main-sequence star is referred to as a dwarf star, this class of star may also be termed a yellow-white dwarf (not to be confused with white dwarfs, remnant stars that are a possible final stage of stellar evolution). Notable examples include Procyon A, Gamma Virginis A and B, and KIC 8462852. Spectral standard stars The revised Yerkes Atlas system (Johnson & Morgan 1953) listed a dense grid of F-type dwarf spectral standard stars; however, not all of these have survived to this day as stable standards. The ''anchor points'' of the MK spectral classification system among the F-type main-sequence dwarf stars, i.e. thos ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
IAU Working Group On Star Names
The International Astronomical Union (IAU) established a Working Group on Star Names (WGSN) in May 2016 to catalog and standardize proper names for stars for the international astronomical community. It operates under Division C – Education, Outreach and Heritage. The IAU states that it is keen to make a distinction between the terms ''name'' and ''designation''. To the IAU, ''name'' refers to the (usually colloquial) term used for a star in everyday conversation, while ''designation'' is solely alphanumerical, and used almost exclusively in official catalogues and for professional astronomy. (The WGSN notes that transliterated Bayer designations (e.g., Tau Ceti) are considered a special historical case and are treated as designations.) Terms of reference The terms of reference for the WGSN for the period 2016–2018 were approved by the IAU Executive Committee at its meeting on 6 May 2016. In summary, these are to: * establish IAU guidelines for the proposal and a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Habitable Worlds Observatory
The Habitable Worlds Observatory (HWO) is a proposed next generation space telescope, a successor of the flagship Hubble, Webb and Roman projects. It would have a large 6–8 meter mirror and be able to detect infrared, optical, and ultraviolet wavelengths. Its primary mission would be to search for and image Earth-size habitable exoplanets in the habitable zones of their stars, where liquid water can exist, by using a coronagraph or a starshade to block out the light of their stars. Beyond planets, it will also observe galaxies. The proposed launch date is 2041, a tentative date because U.S. President Donald Trump has promised to defund and dismantle the Roman telescope only a year away from launch. Mission goals HWO’s main objective would be to identify and directly image at least 25 potentially habitable worlds. It would then use spectroscopy to search for chemical biosignatures in these planets’ atmospheres, including gases such as oxygen and methane, which could s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coptic Language
Coptic () is a dormant language, dormant Afroasiatic languages, Afroasiatic language. It is a group of closely related Egyptian dialects, representing the most recent developments of the Ancient Egyptian language, Egyptian language, and historically spoken by the Copts, starting from the third century AD in Roman Egypt. Coptic was supplanted by Arabic as the primary Vernacular, spoken language of Egypt following the Arab conquest of Egypt and was slowly replaced over the centuries. Coptic has no native speakers today apart from a number of priests, although it remains in daily use as the Sacred language, liturgical language of the Coptic Orthodox Church and of the Coptic Catholic Church. It is written with the Coptic alphabet, a modified form of the Greek alphabet with seven additional letters borrowed from the Demotic (Egyptian), Demotic Egyptian script. The major Coptic dialects are Sahidic, Bohairic, Akhmimic, Fayyumic, Lycopolitan (Asyutic), and Oxyrhynchite. Sahidic Coptic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eta Ophiuchi
Eta Ophiuchi (η Ophiuchi, abbreviated Eta Oph, η Oph) is a binary star in the constellation of Ophiuchus. With a combined apparent magnitude of +2.43, it is the second-brightest of the constellation and one of the brightest stars in the night sky. Based on parallax measurements taken during the Hipparcos mission, it is approximately 88 light-years away. Eta Ophiuchi is part of a multiple star system designated WDS J17104-1544. It itself is designated WDS J17104-1544AB and its two components WDS J17104-1544A (also called Sabik , the traditional name for the system) and WDS J17104-1544B. The 'C' component is UCAC4 372-080717 and 'D' is UCAC2 26022336. Nomenclature ''η Ophiuchi'' ( Latinised to ''Eta Ophiuchi'') is the system's Bayer designation. WDS J17104-1544AB is its designation in the Washington Double Star Catalog. The designations of the two components as WDS J17104-1544 A and B derive from the convention used by the Washington Multiplicity Catalog (WMC) for multi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Khwarazm
Khwarazm (; ; , ''Xwârazm'' or ''Xârazm'') or Chorasmia () is a large oasis region on the Amu Darya river delta in western Central Asia, bordered on the north by the (former) Aral Sea, on the east by the Kyzylkum Desert, on the south by the Karakum Desert, and on the west by the Ustyurt Plateau. It was the center of the Iranian peoples, Iranian Khwarezmian language, Khwarezmian civilization, and a series of kingdoms such as the Afrighid dynasty and the Anushtegin dynasty, whose capitals were (among others) Kath (city), Kath, Gurganj (now Konye-Urgench) andfrom the 16th century onKhiva. Today Khwarazm belongs partly to Uzbekistan and partly to Turkmenistan. Names and etymology Names Khwarazm has been known also as ''Chorasmia'', ''Khaurism'', ''Khwarezm'', ''Khwarezmia'', ''Khwarizm'', ''Khwarazm'', ''Khorezm'', ''Khoresm'', ''Khorasam'', ''Kharazm'', ''Harezm'', ''Horezm'', and ''Chorezm''. In Avestan the name is '; in Old Persian 𐎢𐎺𐎠𐎼𐏀𐎷𐎡𐏁 or ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sogdia
Sogdia () or Sogdiana was an ancient Iranian peoples, Iranian civilization between the Amu Darya and the Syr Darya, and in present-day Uzbekistan, Turkmenistan, Tajikistan, Kazakhstan, and Kyrgyzstan. Sogdiana was also a province of the Achaemenid Empire, and listed on the Behistun Inscription of Darius the Great. Sogdiana was first conquered by Cyrus the Great, the founder of the Achaemenid Empire, and then was annexed by the Macedonian ruler Alexander the Great in 328 BC. It would continue to change hands under the Seleucid Empire, the Greco-Bactrian Kingdom, the Kushan Empire, the Sasanian Empire, the Hephthalite Empire, the Western Turkic Khaganate, and the Muslim conquest of Transoxiana. The Sogdian city-states, although never politically united, were centered on the city of Samarkand. Sogdian language, Sogdian, an Eastern Iranian language, is no longer spoken. However, a descendant of one of its dialects, Yaghnobi language, Yaghnobi, is still spoken by the Yaghnobis of Taji ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Theta Ophiuchi
Theta Ophiuchi, Latinized from θ Ophiuchi, is a multiple star system in the equatorial constellation of Ophiuchus. It lies on the "right foot" of the serpent-bearer, just southwest of Kepler's Star, the nova of 1604. This star has an apparent visual magnitude of +3.3, making it readily visible to the naked eye. Based upon parallax measurements from the Hipparcos mission, it is roughly from Earth. It is 1.8 degrees south of the ecliptic and therefore subject to lunar occultations and (very rarely) occulted by a planet. The next occultation by a planet will be by Mars on 3 October 2078. Theta Ophiuchi appears to be a triple star system. The brightest component is a spectroscopic binary with an orbital period of 56.71 days and an eccentricity of 0.17. The third component is 5.5 magnitude star with a stellar classification of B5. Its angular separation from the binary pair is 0.15 arcseconds. This system is a proper motion member of the Upper Scorpius sub-gro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
