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Gamma Andromedae
Gamma Andromedae, Latinized from γ Andromedae, is the third-brightest point of light in the northern constellation of Andromeda. It is a multiple star system approximately 350 light-years from Earth. The system is drifting closer to the Sun with a radial velocity in the range of −12 to −14 km/s. Observation In 1778, German physicist Johann Tobias Mayer discovered that γ Andromedae is a double star. When examined in a small telescope, it appears to be a bright, golden-yellow star next to a dimmer, indigo-blue star, separated by approximately 10 arcseconds. The pair is often considered by stargazers to be a beautiful double star with a striking contrast of color. The brighter member, γ1 Andromedae, is the primary of the system, and is thus designated component γ Andromedae A. It has the official proper name Almach , which was used as the traditional name of the naked eye star, and thus the system as a whole. The fainter secondary is γ2 And ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
J2000
In astronomy, an epoch or reference epoch is a instant, moment in time used as a reference point for some time-varying astronomical quantity. It is useful for the celestial coordinates or orbital elements of a Astronomical object, celestial body, as they are subject to Perturbation (astronomy), perturbations and vary with time. These time-varying astronomical quantities might include, for example, the mean longitude or mean anomaly of a body, the node of its orbit relative to a reference plane, the direction of the apogee or Perihelion and aphelion, aphelion of its orbit, or the size of the major axis of its orbit. The main use of astronomical quantities specified in this way is to calculate other relevant parameters of motion, in order to predict future positions and velocities. The applied tools of the disciplines of celestial mechanics or its subfield orbital mechanics (for predicting orbital paths and positions for bodies in motion under the gravitational effects of other bodi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arcseconds
A minute of arc, arcminute (arcmin), arc minute, or minute arc, denoted by the symbol , is a unit of angular measurement equal to of one degree. Since one degree is of a turn (or complete rotation), one minute of arc is of a turn. The nautical mile (nmi) was originally defined as the arc length of a minute of latitude on a spherical Earth, so the actual Earth circumference is very near . A minute of arc is of a radian. A second of arc, arcsecond (arcsec), or arc second, denoted by the symbol , is of an arcminute, of a degree, of a turn, and (about ) of a radian. These units originated in Babylonian astronomy as sexagesimal subdivisions of the degree; they are used in fields that involve very small angles, such as astronomy, optometry, ophthalmology, optics, navigation, land surveying, and marksmanship. To express even smaller angles, standard SI prefixes can be employed; the milliarcsecond (mas) and microarcsecond (μas), for instance, are commonly used in astron ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
τ Cet
Tau Ceti, Latinized from τ Ceti, is a single star in the constellation Cetus that is spectrally similar to the Sun, although it has only about 78% of the Sun's mass. At a distance of just under from the Solar System, it is a relatively nearby star and the closest solitary G-class star. The star appears stable, with little stellar variation, and is metal-deficient relative to the Sun. It can be seen with the unaided eye with an apparent magnitude of 3.5. As seen from Tau Ceti, the Sun would be in the northern hemisphere constellation Boötes with an apparent magnitude of about 2.6.From Tau Ceti the Sun would appear on the diametrically opposite side of the sky at the coordinates RA = , Dec = , which is located near Tau Boötis. The absolute magnitude of the Sun is 4.8, so, at a distance of , the Sun would have an apparent magnitude m = M_v + 5 \cdot (\log_ 3.64 - 1) = 2.6. Observations have detected more than ten times as much dust surrounding T ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Theta Ceti
Theta Ceti, Latinized from θ Ceti, is a solitary, orange-hued star in the equatorial constellation of Cetus. It is visible to the naked eye with an apparent visual magnitude of 3.60. Based upon an annual parallax shift of 28.66 mas as seen from Earth, it is located about 114 light years from the Sun. At that distance, the visual magnitude is diminished by an extinction factor of 0.10 due to interstellar dust. With an age of about 2.2 billion years, this is an evolved, K-type giant star with a stellar classification of K0 III. It is a red clump star on the horizontal branch, which means it is generating energy through helium fusion at its core. The star has an estimated 1.8 times the mass of the Sun and has expanded to 10 times the Sun's radius. It is radiating 53 times the solar luminosity from its photosphere at an effective temperature of 4,660 K. Name In the catalogue of stars in the ''Calendarium of Al Achsasi Al Mouakket'', this star was d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eta Ceti
Eta Ceti (η Cet, η Ceti) is a star in the equatorial constellation of Cetus. It has the traditional name Deneb Algenubi or Algenudi. The apparent visual magnitude of this star is +3.4, making it the fourth-brightest star in this otherwise relatively faint constellation. The distance to this star can be measured directly using the parallax technique, yielding a value of . This is a giant star that has been chosen a standard for the stellar classification of K2−IIIb. It has exhausted the hydrogen at its core and evolved away from the main sequence of stars like the Sun. (The classification is sometimes listed as K1.5 IIICN1Fe0.5, indicating a strong CN star with higher than normal abundance of cyanogen and iron relative to other stars of its class.) It is a red clump star that is generating energy through the nuclear fusion of helium at its core. Eta Ceti may have slightly more mass than the Sun and its outer envelope has expanded to 15 times the Sun's radiu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Latin
Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the Roman Republic it became the dominant language in the Italian region and subsequently throughout the Roman Empire. Even after the fall of Western Rome, Latin remained the common language of international communication, science, scholarship and academia in Europe until well into the 18th century, when other regional vernaculars (including its own descendants, the Romance languages) supplanted it in common academic and political usage, and it eventually became a dead language in the modern linguistic definition. Latin is a highly inflected language, with three distinct genders (masculine, feminine, and neuter), six or seven noun cases (nominative, accusative, genitive, dative, ablative, and vocative), five declensions, four verb conjuga ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Al Achsasi Al Mouakket
Muḥammad al-Akhṣāṣī al-Muwaqqit ( ar, محمد الاخصاصي الموقت) was an Egyptian astronomer whose and catalogue of stars, ('Pearls of brilliance upon the solar operations'), was written at Cairo about 1650. Al-Akhsasi was a shaykh, a learned elder, of the Grand Mosque of the university of Cairo, where his name ''al- Muwaqqit'' reflected his position regulating the times and hours at the mosque. His name Akhsasi connects him in origin to a village in the Faiyum, southwest of Cairo. No copies of his book were known to Western astronomers or historians of science The history of science covers the development of science from ancient times to the present. It encompasses all three major branches of science: natural, social, and formal. Science's earliest roots can be traced to Ancient Egypt and Mesop ... until 1895;Knobel 1895. thus he did not appear in the standard French and English bibliographies and library catalogues of the 19th century. Notes ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Caracal
The caracal (''Caracal caracal'') () is a medium-sized wild cat native to Africa, the Middle East, Central Asia, and arid areas of Pakistan and northwestern India. It is characterised by a robust build, long legs, a short face, long tufted ears, and long canine teeth. Its coat is uniformly reddish tan or sandy, while the ventral parts are lighter with small reddish markings. It reaches at the shoulder and weighs . It was first scientifically described by German naturalist Johann Christian Daniel von Schreber in 1776. Three subspecies are recognised. Typically nocturnal, the caracal is highly secretive and difficult to observe. It is territorial, and lives mainly alone or in pairs. The caracal is a carnivore that typically preys upon small mammals, birds, and rodents. It can leap higher than and catch birds in midair. It stalks its prey until it is within of it, after which it runs it down and kills its prey with a bite to the throat or to the back of the neck. Both sexes b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arabic
Arabic (, ' ; , ' or ) is a Semitic languages, Semitic language spoken primarily across the Arab world.Semitic languages: an international handbook / edited by Stefan Weninger; in collaboration with Geoffrey Khan, Michael P. Streck, Janet C. E.Watson; Walter de Gruyter GmbH & Co. KG, Berlin/Boston, 2011. Having emerged in the 1st century, it is named after the Arabs, Arab people; the term "Arab" was initially used to describe those living in the Arabian Peninsula, as perceived by geographers from ancient Greece. Since the 7th century, Arabic has been characterized by diglossia, with an opposition between a standard Prestige (sociolinguistics), prestige language—i.e., Literary Arabic: Modern Standard Arabic (MSA) or Classical Arabic—and diverse vernacular varieties, which serve as First language, mother tongues. Colloquial dialects vary significantly from MSA, impeding mutual intelligibility. MSA is only acquired through formal education and is not spoken natively. It is ... [...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] |
International Astronomical Union
The International Astronomical Union (IAU; french: link=yes, Union astronomique internationale, UAI) is a nongovernmental organisation with the objective of advancing astronomy in all aspects, including promoting astronomical research, outreach, education, and development through global cooperation. It was founded in 1919 and is based in Paris, France. The IAU is composed of individual members, who include both professional astronomers and junior scientists, and national members, such as professional associations, national societies, or academic institutions. Individual members are organised into divisions, committees, and working groups centered on particular subdisciplines, subjects, or initiatives. As of 2018, the Union had over 13,700 individual members, spanning 90 countries, and 82 national members. Among the key activities of the IAU is serving as a forum for scientific conferences. It sponsors nine annual symposia and holds a triannual General Assembly that sets policy ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Star System
A star system or stellar system is a small number of stars that orbit each other, bound by gravitational attraction. A large group of stars bound by gravitation is generally called a '' star cluster'' or '' galaxy'', although, broadly speaking, they are also star systems. Star systems are not to be confused with planetary systems, which include planets and similar bodies (such as comets). A star system of two stars is known as a '' binary star'', ''binary star system'' or ''physical double star''. If there are no tidal effects, no perturbation from other forces, and no transfer of mass from one star to the other, such a system is stable, and both stars will trace out an elliptical orbit around the barycenter of the system indefinitely. ''(See Two-body problem)''. Examples of binary systems are Sirius, Procyon and Cygnus X-1, the last of which probably consists of a star and a black hole. Multiple star systems A multiple star system consists of three or more stars that ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
