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68 Cygni
68 Cygni is a star in the constellation Cygnus. Located approximately distant, the star is a hot blue giant of spectral type O7.5IIIn((f)), a massive star that is likely currently expanding to become a supergiant. The star is surrounded by a ring-shaped nebula (likely a Strömgren sphere) named Sharpless 2-119 (''Clamshell nebula''). 68 Cygni is currently classified as a rotating ellipsoidal variable, varying between apparent magnitudes 4.98 and 5.09, although the classification as a rotating ellipsoidal variable is subject to controversy. Barely visible to the naked eye, the star is likely to have a mass of around 26 solar masses and a temperature of approximately 34,000 kelvins, although many of the star's physical parameters are subject to uncertainties due to the unclear nature of the system. Naming Being visible to the naked eye, 68 Cygni would have been observable since ancient times, but the first known cataloging and designation of the star was by Johann Bay ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Flamsteed Designation
A Flamsteed designation is a combination of a number and constellation name that uniquely identifies most naked eye stars in the 88 modern constellations, modern constellations visible from southern England. They are named after John Flamsteed, author of the ''Historia Coelestis Britannica'', the first major star catalogue compiled with the aid of a telescope. Flamsteed’s own catalogue did not include what are now known as Flamsteed numbers, but its listing of stars in each constellation provided the basis for later astronomers to add them. Description Flamsteed designations for stars are similar to Bayer designations, except that they use numbers instead of Greek and Roman letters. Each star is assigned a number and the Latin genitive of the constellation it lies in (see 88 modern constellations for a list of constellations and the genitive forms of their names). Flamsteed designations were assigned to 2554 stars. The numbers were originally assigned in order of increasing righ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Strömgren Sphere
In theoretical astrophysics, there can be a sphere of ionized hydrogen (H II) around a young star of the spectral classes O or B. The theory was derived by Bengt Strömgren in 1937 and later named Strömgren sphere after him. The Rosette Nebula is the most prominent example of this type of emission nebula from the H II-regions. The physics Very hot stars of the spectral class O or B emit very energetic radiation, especially ultraviolet radiation, which is able to ionize the neutral hydrogen (H I) of the surrounding interstellar medium, so that hydrogen atoms lose their single electrons. This state of hydrogen is called H II. After a while, free electrons recombine with those hydrogen ions. Energy is re-emitted, not as a single photon, but rather as a series of photons of lesser energy. The photons lose energy as they travel outward from the star's surface, and are not energetic enough to again contribute to ionization. Otherwise, the entire interstellar medium would be ioni ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Variable Star Designation
In astronomy, a variable-star designation is a unique identifier given to variable stars. It extends the Bayer designation format, with an identifying label (as described below) preceding the Latin genitive of the name of the constellation in which the star lies. The identifying label can be one or two Latin letters or a ''V'' plus a number (e.g. V399). Examples are R Coronae Borealis, YZ Ceti, V603 Aquilae. (''See'' List of constellations ''for a list of constellations and the genitive forms of their names''.) Naming The current naming system is: * Stars with existing Greek letter Bayer designations are not given new designations. * Otherwise, start with the letter R and go through Z. * Continue with RR–RZ, then use SS–SZ, TT–TZ and so on until ZZ. * After ZZ return to the beginning of the Latin alphabet and use AA–AZ, BB–BZ, CC–CZ, and so on, until reaching QZ, but omitting the letter J in either first or second position. * Abandon the Latin letters after all ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Joseph Jérôme De Lalande
Joseph is a common male name, derived from the Hebrew (). "Joseph" is used, along with " Josef", mostly in English, French and partially German languages. This spelling is also found as a variant in the languages of the modern-day Nordic countries. In Portuguese and Spanish, the name is "José". In Arabic, including in the Quran, the name is spelled , . In Kurdish (''Kurdî''), the name is , Persian, the name is , and in Turkish it is . In Pashto the name is spelled ''Esaf'' (ايسپ) and in Malayalam it is spelled ''Ousep'' (ഔസേപ്പ്). In Tamil, it is spelled as ''Yosepu'' (யோசேப்பு). The name has enjoyed significant popularity in its many forms in numerous countries, and ''Joseph'' was one of the two names, along with ''Robert'', to have remained in the top 10 boys' names list in the US from 1925 to 1972. It is especially common in contemporary Israel, as either "Yossi" or "Yossef", and in Italy, where the name "Giuseppe" was the most common m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
John Flamsteed
John Flamsteed (19 August 1646 – 31 December 1719) was an English astronomer and the first Astronomer Royal. His main achievements were the preparation of a 3,000-star catalogue, ''Catalogus Britannicus'', and a star atlas called '' Atlas Coelestis'', both published posthumously. He also made the first recorded observations of Uranus, although he mistakenly catalogued it as a star, and he laid the foundation stone for the Royal Greenwich Observatory. Life Flamsteed was born in Denby, Derbyshire, England, the only son of Stephen Flamsteed and his first wife, Mary Spadman. He was educated at the free school of Derby and at Derby School, in St Peter's Churchyard, Derby, near where his father carried on a malting business. At that time, most masters of the school were Puritans. Flamsteed had a solid knowledge of Latin, essential for reading the scientific literature of the day, and a love of history, leaving the school in May 1662.Birks, John L. (1999) ''John Flamsteed, t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Latin Alphabet
The Latin alphabet, also known as the Roman alphabet, is the collection of letters originally used by the Ancient Rome, ancient Romans to write the Latin language. Largely unaltered except several letters splitting—i.e. from , and from —additions such as , and extensions such as letters with diacritics, it forms the Latin script that is used to write most languages of modern Languages of Europe, Europe, languages of Africa, Africa, languages of the Americas, the Americas, and Languages of Oceania, Oceania. Its basic modern inventory is standardized as the ISO basic Latin alphabet. Etymology The term ''Latin alphabet'' may refer to either the alphabet used to write Latin (as described in this article) or other alphabets based on the Latin script, which is the basic set of letters common to the various alphabets descended from the classical Latin alphabet, such as the English alphabet. These Latin-script alphabets may discard letters, like the Rotokas alphabet, or add new ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Right Ascension
Right ascension (abbreviated RA; symbol ) is the angular distance of a particular point measured eastward along the celestial equator from the Sun at the equinox (celestial coordinates), March equinox to the (hour circle of the) point in question above the Earth. When paired with declination, these celestial coordinate system, astronomical coordinates specify the location of a point on the celestial sphere in the equatorial coordinate system. An old term, ''right ascension'' (), "''Ascensio recta'' Solis, stellæ, aut alterius cujusdam signi, est gradus æquatorus cum quo simul exoritur in sphæra recta"; roughly translated, "''Right ascension'' of the Sun, stars, or any other sign, is the degree of the equator that rises together in a right sphere" refers to the ''ascension'', or the point on the celestial equator that rises with any celestial object as seen from Earth's equator, where the celestial equator perpendicular, intersects the horizon at a right angle. It contrasts wi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Greek Alphabet
The Greek alphabet has been used to write the Greek language since the late 9th or early 8th century BC. It was derived from the earlier Phoenician alphabet, and is the earliest known alphabetic script to systematically write vowels as well as consonants. In Archaic Greece, Archaic and early Classical Greece, Classical times, the Greek alphabet existed in Archaic Greek alphabets, many local variants, but, by the end of the 4th century BC, the Ionia, Ionic-based Euclidean alphabet, with 24 letters, ordered from alpha to omega, had become standard throughout the Greek-speaking world and is the version that is still used for Greek writing today. The letter case, uppercase and lowercase forms of the 24 letters are: : , , , , , , , , , , , , , , , , , , , , , , , The Greek alphabet is the ancestor of several scripts, such as the Latin script, Latin, Gothic alphabet, Gothic, Coptic script, Coptic, and Cyrillic scripts. Throughout antiquity, Greek had only a single uppercas ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Astrophysical Journal
''The Astrophysical Journal'' (''ApJ'') is a peer-reviewed scientific journal of astrophysics and astronomy, established in 1895 by American astronomers George Ellery Hale and James Edward Keeler. The journal discontinued its print edition and became an electronic-only journal in 2015. Since 1953, ''The Astrophysical Journal Supplement Series'' (''ApJS'') has been published in conjunction with ''The Astrophysical Journal'', with generally longer articles to supplement the material in the journal. It publishes six volumes per year, with two 280-page issues per volume. ''The Astrophysical Journal Letters'' (''ApJL''), established in 1967 by Subrahmanyan Chandrasekhar as Part 2 of ''The Astrophysical Journal'', is now a separate journal focusing on the rapid publication of high-impact astronomical research. The three journals were published by the University of Chicago Press for the American Astronomical Society until, in January 2009, publication was transferred to IOP Publis ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Johann Bayer
Johann Bayer (; 1572 – 7 March 1625) was a German lawyer and uranographer (celestial cartographer). He was born in Rain in 1572. In 1592, aged 20, he began his study of philosophy and law at the University of Ingolstadt, after which he moved to Augsburg to begin work as a lawyer, becoming legal adviser to the city council in 1612. Bayer had several interests outside his work, including archaeology and mathematics. However, he is primarily known for his work in astronomy; particularly for his work on determining the positions of objects on the celestial sphere. He remained unmarried and died in 1625. Bayer's star atlas '' Uranometria Omnium Asterismorum'' (" Uranometry of all the asterisms") was first published in 1603 in Augsburg and dedicated to two prominent local citizens. This was the first atlas to cover the entire celestial sphere. It was based upon the work of Tycho Brahe and may have borrowed from Alessandro Piccolomini's 1540 star atlas, ''De le stelle fiss ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kelvin
The kelvin (symbol: K) is the base unit for temperature in the International System of Units (SI). The Kelvin scale is an absolute temperature scale that starts at the lowest possible temperature (absolute zero), taken to be 0 K. By definition, the Celsius scale (symbol °C) and the Kelvin scale have the exact same magnitude; that is, a rise of 1 K is equal to a rise of 1 °C and vice versa, and any temperature in degrees Celsius can be converted to kelvin by adding 273.15. The 19th century British scientist Lord Kelvin first developed and proposed the scale. It was often called the "absolute Celsius" scale in the early 20th century. The kelvin was formally added to the International System of Units in 1954, defining 273.16 K to be the triple point of water. The Celsius, Fahrenheit, and Rankine scales were redefined in terms of the Kelvin scale using this definition. The 2019 revision of the SI now defines the kelvin in terms of energy by setting the Bo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
