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Alpha Hydrae
Alphard , designated Alpha Hydrae (α Hydrae, abbreviated Alpha Hya, α Hya), is the brightest star in the constellation of Hydra. It is a single giant star, cooler than the Sun but larger and more luminous. It is about 177 light-years away. Nomenclature ''α Hydrae'' ( Latinised to ''Alpha Hydrae'') is the star's Bayer designation. The traditional name ''Alphard'' is from the Arabic الفرد (''al-fard''), "the individual", there being no other bright stars near it. It was also known as the "backbone of the Serpent" to the Arabs. In the catalogue of stars in the ''Calendarium of Al Achsasi Al Mouakket'', it was designated ''Soheil al Fard'', which was translated into Latin as ''Soheil Solitarius'', meaning ''the bright solitary one''. In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN) to catalog and standardize proper names for stars. The WGSN's first bulletin of July 2016 included a table of the first two batches of names ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hydra (constellation)
Hydra is the largest of the 88 modern constellations, measuring 1303 square degrees, and also the longest at over 100 degrees. Its southern end borders Libra and Centaurus and its northern end borders Cancer. It was included among the 48 constellations listed by the 2nd century astronomer Ptolemy. Commonly represented as a water snake, it straddles the celestial equator. History and mythology Western mythology The Greek constellation of Hydra is an adaptation of a Babylonian constellation: the MUL.APIN includes a "serpent" constellation (MUL.DINGIR.MUŠ) that loosely corresponds to Hydra. It is one of two Babylonian "serpent" constellations (the other being the origin of the Greek Serpens), a mythological hybrid of serpent, lion and bird. The shape of Hydra resembles a twisting snake, and features as such in some Greek myths. One myth associates it with a water snake that a crow served Apollo in a cup when it was sent to fetch water; Apollo saw through the fraud, and angr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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] |
History Of China
The earliest known written records of the history of China date from as early as 1250 BC, from the Shang dynasty (c. 1600–1046 BC), during the reign of king Wu Ding. Ancient historical texts such as the '' Book of Documents'' (early chapters, 11th century BC), the '' Bamboo Annals'' (c. 296 BC) and the ''Records of the Grand Historian'' (c. 91 BC) describe a Xia dynasty before the Shang, but no writing is known from the period, and Shang writings do not indicate the existence of the Xia. The Shang ruled in the Yellow River valley, which is commonly held to be the cradle of Chinese civilization. However, Neolithic civilizations originated at various cultural centers along both the Yellow River and Yangtze River. These Yellow River and Yangtze civilizations arose millennia before the Shang. With thousands of years of continuous history, China is among the world's oldest civilizations and is regarded as one of the cradles of civilization. The Zhou dynasty (1046–256 BC) supp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
27 Hydrae
27 Hydrae is a member of a triple star system system in the equatorial constellation of Hydra, located 222 light years away from the Sun. It is visible to the naked eye as a faint, orange-hued star with a combined apparent visual magnitude of 4.82. The system is moving further from the Earth with a heliocentric radial velocity of +25.6 km/s. The magnitude 4.91 primary, component A, is an aging giant star with a stellar classification of K0 III. It is a red clump giant, which indicates it is on the horizontal branch and is generating energy through helium fusion at its core. The star is 1.9 billion years old with 2.17 times the mass of the Sun. It has swelled to 11 times the Sun's radius and is radiating 57.5 times the Sun's luminosity from its enlarged photosphere at an effective temperature of 4,965 K. The star is suspected to host a low-mass companion. The stellar companions to this star, designated components B and C, lie at an angula ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
26 Hydrae
26 Hydrae is a binary star system located 334 light years away from the Sun in the equatorial constellation of Hydra. It is visible to the naked eye as a faint, yellow-hued point of light with a combined apparent visual magnitude of 4.77, just a few degrees away from Alphard. The system is moving closer to the Earth with a leisurely radial velocity of -1 km/s. Keenan and McNeil (1989) gave the brighter component a stellar classification of G7 III, matching an aging giant star. Houk and Swift (1999) have it classed as a G8II bright giant. This is a red clump giant, which indicates it is on the horizontal branch and is generating energy through helium fusion at its core. It has a high lithium abundance and displays a far infrared emission excess. The star is an estimated 510 million years old with 2.72 times the mass of the Sun and has expanded to 15 times the Sun's radius. It is radiating 139 times the luminosity of the Sun from its swollen ph ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ι Hydrae
Iota Hydrae (ι Hydrae, abbreviated Iota Hya, ι Hya), formally named Ukdah , is a star in the constellation of Hydra, about 8° to the north-northwest of Alphard (Alpha Hydrae) and just to the south of the celestial equator. Visible to the naked eye, it is a suspected variable star with an apparent visual magnitude that ranges between 3.87 and 3.91. Based upon an annual parallax shift of 12.39 mas measured during the Hipparcos mission, it is located around 263 light-years from the Sun. Nomenclature ''ι Hydrae'' ( Latinised to ''Iota Hydrae'') is the star's Bayer designation. This star along with Tau¹ Hydrae, Tau² Hydrae and 33 Hydrae (A Hydrae), were Ptolemy's Καμπή (Kampē); but Kazwini knew them as عقدة ''ʽuqdah'' (or ''ʽuḳdah'') "knot". According to a 1971 NASA memorandum, ''Ukdah'' was the name of an asterism of four stars: Tau¹ Hydrae as ''Uḳdah I'', Tau² Hydrae as ''Uḳdah II'', 33 Hydrae as ''Uḳdah III'' and Iota Hydrae ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tau2 Hydrae
Tau2 Hydrae is a probable astrometric binary star system in the equatorial constellation of Hydra. Based upon an annual parallax shift of 6.30 mas as seen from Earth, it is located around 520 light years from the Sun. The brighter component is visible to the naked eye with an apparent visual magnitude of +4.56. The primary member, component A, is an A-type main sequence star with a stellar classification of A3 V. It is a suspected variable of unknown type, with an amplitude of 0.06 in visual magnitude. The star has around 4.5 times the radius of the Sun and is radiating about 285 times the solar luminosity from its photosphere at an effective temperature The effective temperature of a body such as a star or planet is the temperature of a black body that would emit the same total amount of electromagnetic radiation. Effective temperature is often used as an estimate of a body's surface temperature ... of 7,918 K. References {{DEFAULTSORT:T ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tau1 Hydrae
Tau1 Hydrae is a triple star system in the equatorial constellation of Hydra. Based upon the annual parallax shift of the two visible components as seen from Earth, they are located about from the Sun. The system has a combined apparent visual magnitude of +4.59, which is bright enough to be visible to the naked eye at night. The inner pair of stars form a single-lined spectroscopic binary with an orbital period of about 2,807 days and an eccentricity of 0.33. The visible member of the pair, component A, is a visual magnitude 4.60 F-type main sequence star with a stellar classification of F6 V. During the 1990s, it was thought to be a Gamma Doradus variable, but this was later discounted as it shows no short-term photometric variability. The star does show some long-term variability, possibly as a result of a magnetic activity cycle similar to the solar cycle. The tertiary member, component B, is a visual magnitude 7.15 K-type star with a class of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Asterism (astronomy)
An asterism is an observed pattern or group of stars in the sky. Asterisms can be any identified pattern or group of stars, and therefore are a more general concept than the formally defined 88 constellations. Constellations are based on asterisms, but unlike asterisms, constellations outline and today completely divide the sky and all its celestial objects into regions around their central asterisms. For example, the asterism known as the Big Dipper comprises the seven brightest stars in the constellation Ursa Major. Another is the asterism of the Southern Cross, within the constellation of Crux. Asterisms range from simple shapes of just a few stars to more complex collections of many stars covering large portions of the sky. The stars themselves may be bright naked-eye objects or fainter, even telescopic, but they are generally all of a similar brightness to each other. The larger brighter asterisms are useful for people who are familiarizing themselves with the night sky. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Star (Chinese Constellation)
The Star mansion (星宿, pinyin: Xīng Xiù) is one of the Twenty-eight mansions of the Chinese constellations. It is one of the southern mansions of the Vermilion Bird The Vermilion Bird ( zh, c=朱雀, p=Zhūquè) is one of the Four Symbols of the Chinese constellations. According to Wu Xing, the Taoist five elemental system, it represents the Fire element, the direction south, and the season summer correspo .... Asterisms References {{Chinese constellation Chinese constellations ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
