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Deneb
Deneb () is a first-magnitude star in the constellation of Cygnus, the swan. Deneb is one of the vertices of the asterism known as the Summer Triangle and the "head" of the Northern Cross. It is the brightest star in Cygnus and the 19th brightest star in the night sky, with an average apparent magnitude of +1.25. A blue-white supergiant, Deneb rivals Rigel as the most luminous first-magnitude star. However, its distance, and hence luminosity, is poorly known; its luminosity is somewhere between 55,000 and 196,000 times that of the Sun. Its Bayer designation is α Cygni, which is Latinised to Alpha Cygni, abbreviated to Alpha Cyg or α Cyg. Nomenclature ''α Cygni'' (Latinised to ''Alpha Cygni'') is the star's designation given by Johann Bayer in 1603. The traditional name ''Deneb'' is derived from the Arabic word for "tail", from the phrase ذنب الدجاجة ''Dhanab al-Dajājah'', or "tail of the hen". The IAU Working Group on Star Names has recognised t ...
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Cygnus (constellation)
Cygnus is a northern constellation on the plane of the Milky Way, deriving its name from the Latinized Greek word for swan. Cygnus is one of the most recognizable constellations of the northern summer and autumn, and it features a prominent asterism known as the Northern Cross (in contrast to the Southern Cross). Cygnus was among the 48 constellations listed by the 2nd century astronomer Ptolemy, and it remains one of the 88 modern constellations. Cygnus contains Deneb (ذنب, translit. ''ḏanab,'' tail)one of the brightest stars in the night sky and the most distant first-magnitude staras its "tail star" and one corner of the Summer Triangle. It also has some notable X-ray sources and the giant stellar association of Cygnus OB2. Cygnus is also known as the Northern Cross. One of the stars of this association, NML Cygni, is one of the largest stars currently known. The constellation is also home to Cygnus X-1, a distant X-ray binary containing a supergiant and unsee ...
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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 ...
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Summer Triangle
The Summer Triangle is an astronomical asterism in the northern celestial hemisphere. The defining vertices of this imaginary triangle are at Altair, Deneb, and Vega, each of which is the brightest star of its constellation ( Aquila, Cygnus, and Lyra, respectively). The greatest declination is +45° (rounded) and lowest is +9° (rounded) meaning the three can be seen from all places in the Northern Hemisphere and from the home of most of people resident in the Southern Hemisphere. The two stars in Aquila and Cygnus represent the head of an eagle and tail of a swan and these asterisms do not overlap, two small constellations intervening. History The term was popularized by American author H. A. Rey and British astronomer Patrick Moore in the 1950s. The name can be found in constellation guidebooks as far back as 1913. The Austrian astronomer Oswald Thomas described these stars as ''Grosses Dreieck'' (Great Triangle) in the late 1920s and ''Sommerliches Dreieck'' (Summerl ...
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Summer Triangle
The Summer Triangle is an astronomical asterism in the northern celestial hemisphere. The defining vertices of this imaginary triangle are at Altair, Deneb, and Vega, each of which is the brightest star of its constellation ( Aquila, Cygnus, and Lyra, respectively). The greatest declination is +45° (rounded) and lowest is +9° (rounded) meaning the three can be seen from all places in the Northern Hemisphere and from the home of most of people resident in the Southern Hemisphere. The two stars in Aquila and Cygnus represent the head of an eagle and tail of a swan and these asterisms do not overlap, two small constellations intervening. History The term was popularized by American author H. A. Rey and British astronomer Patrick Moore in the 1950s. The name can be found in constellation guidebooks as far back as 1913. The Austrian astronomer Oswald Thomas described these stars as ''Grosses Dreieck'' (Great Triangle) in the late 1920s and ''Sommerliches Dreieck'' (Summerl ...
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Alpha Cygni Variable
Alpha Cygni variables are variable stars which exhibit non-radial pulsations, meaning that some portions of the stellar surface are contracting at the same time other parts expand. They are supergiant stars of spectral types B or A. Variations in brightness on the order of 0.1 magnitudes are associated with the pulsations, which often seem irregular, due to beating of multiple pulsation periods. The pulsations typically have periods of several days to several weeks. The prototype of these stars, Deneb (α Cygni), exhibits fluctuations in brightness between magnitudes +1.21 and +1.29. Small amplitude rapid variations have been known in many early supergiant stars, but they were not formally grouped into a class until the 4th edition of the General Catalogue of Variable Stars was published in 1985. It used the acronym ACYG for Alpha Cygni variable stars. Many luminous blue variables (LBVs) show Alpha Cygni-type variability during their quiescent (hot) phases, but the LBV class ...
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First-magnitude Star
First-magnitude stars are the brightest stars in the night sky, with apparent magnitudes lower (i.e. brighter) than +1.50. Hipparchus, in the 1st century B.C., introduced the magnitude scale. He allocated first magnitude to the 20 brightest stars and the sixth magnitude to the faintest stars visible to the naked eye. In the 19th Century, this ancient scale of apparent magnitude was logarithmically defined—so that a star of 1.00 mag is exactly 100 times brighter than a star of 6.00 magnitude. The scale also was extended to even brighter celestial bodies like Sirius (-1.5 mag), Venus (-4 mag), full Moon (-12.7 mag) and Sun (-26.7 mag). Hipparchus Hipparchus ranked his stars in a very simple way. He listed the brightest stars as ''"of the first magnitude"'', which meant "the biggest." Stars less bright Hipparchus called ''"of the second magnitude"'', or second biggest. The faintest stars visible to the naked eye he called ''"of the sixth magnitude"''. Naked-eye magnitude s ...
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Northern Cross (asterism)
The Northern Cross is an astronomical asterism in the northern hemisphere of the celestial sphere, corresponding closely with the constellation Cygnus the swan. It is much larger than the Southern Cross and consists of the brightest stars in Cygnus: Deneb, Sadr, Gienah, Delta Cygni and Albireo. The 'head' of the cross, Deneb, is also part of the Summer Triangle asterism. Like the Summer Triangle, the Northern Cross is an indicator of the seasons. Near midnight, the Cross lies virtually overhead at mid-northern latitudes during the summer months; it can also be seen during spring in the early morning to the East. In the autumn the cross is visible in the evening to the West until November. It never dips below the horizon at or above 45° north latitude, just grazing the northern horizon at its lowest point at such locations as Minneapolis, Montréal and Turin. From the southern hemisphere it appears upside down and low in the sky during the winter months. In Johann Bayer's 17 ...
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List Of Brightest Stars
This is a list of stars arranged by their apparent magnitude – their brightness as observed from Earth. It includes all stars brighter than magnitude +2.50 in visible light, measured using a ''V''-band filter in the UBV photometric system. Stars in binary systems (or other multiples) are listed by their ''total'' or ''combined'' brightness if they appear as a single star to the naked eye, or listed separately if they do not. As with all magnitude systems in astronomy, the scale is logarithmic and inverted i.e. lower/more negative numbers are brighter. Most stars on this list appear bright from Earth because they are nearby, not because they are intrinsically luminous. For a list which compensates for the distances, converting the ''apparent'' magnitude to the ''absolute'' magnitude, see the list of most luminous stars. Measurement The Sun is the brightest star as viewed from Earth, at −26.74 mag. The second brightest is Sirius at −1.46 mag. For c ...
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Rigel
Rigel is a blue supergiant star in the constellation of Orion. It has the Bayer designation β Orionis, which is Latinized to Beta Orionis and abbreviated Beta Ori or β Ori. Rigel is the brightest and most massive componentand the eponymof a star system of at least four stars that appear as a single blue-white point of light to the naked eye. This system is located at a distance of approximately from the Sun. A star of spectral type B8Ia, Rigel is calculated to be anywhere from 61,500 to 363,000 times as luminous as the Sun, and 18 to 24 times as massive, depending on the method and assumptions used. Its radius is more than seventy times that of the Sun, and its surface temperature is . Due to its stellar wind, Rigel's mass-loss is estimated to be ten million times that of the Sun. With an estimated age of seven to nine million years, Rigel has exhausted its core hydrogen fuel, expanded, and cooled to become a supergiant. It is expected to end its life a ...
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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 ...
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Journal For The History Of Astronomy
''Journal for the History of Astronomy'' (''JHA'') is a peer-reviewed academic journal that publishes papers in the History of Astronomy from earliest times to the present, and in history in the service of astronomy. The journal's founding editor was Michael Hoskin of Cambridge University and it is currently edited by James Evans of the University of Puget Sound. It has been in publication since 1970 and is currently published by SAGE Publications. From 1979 to 2002, ''Archaeoastronomy'' was published as a supplement to JHA, but was incorporated into ''JHA'' in 2003. Abstracting and indexing ''Journal for the History of Astronomy'' is abstracted and indexed in, among other databases: SCOPUS, and the Social Sciences Citation Index. According to the '' Journal Citation Reports'', its 2012 impact factor The impact factor (IF) or journal impact factor (JIF) of an academic journal is a scientometric index calculated by Clarivate that reflects the yearly mean number of cita ...
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Philipp Von Zesen
Philipp von Zesen, also Filip Cösius or ''Caesius'' (originally Ph. Caesien, Filip Zesen, Filip von Zesen, in Latin Philippus Caesius à Fürstenau, Philippus Caesius à Zesen) (8 October 1619 O.S. – 13 November 1689 O.S.) was a German poet, hymnist and writer. Some of his works are published under his pen name Ritterhold von Blauen. Biography Von Zesen was born in Priorau near Dessau. From 1639 to 1641 he studied rhetorics and poetry at the University of Wittenberg. During the war years from 1642 to 1648 von Zesen lived in the Dutch Republic working as a translator. In 1648 he returned to his hometown of Priorau and was accepted to the Fruitbearing Society in 1649. From 1656 he worked in the Dutch Republic again, being a major contributor to Elsevier publishing company. When he married Maria Becker in 1672 he moved to Hamburg where he spent the rest of his life. Style Although his purist language found many opponents, a number of the neologisms he coined are still i ...
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