Table of Contents
410 relations: Abd al-Rahman al-Sufi, Absolute magnitude, Achernar, Age of the universe, Akkadian language, Al-Andalus, Al-Biruni, Albert A. Michelson, Algol, Algol paradox, Ali ibn Ridwan, Alnilam, Alpha particle, Altair, Ancient Greece, Ancient Greek astronomy, Ancient Greek philosophy, Ancient Greek religion, Andromeda Galaxy, Angelo Secchi, Angular diameter, Angular momentum, Annie Jump Cannon, Apparent magnitude, Arabic, Aristyllus, Asterisk, Asterism (astronomy), Asteroid, Astrology, Astrometry, Astronomer, Astronomical constant, Astronomical spectroscopy, Astronomical unit, Astronomy in the medieval Islamic world, Asymptotic giant branch, Atomic nucleus, Avempace, Babylon, Babylonian astronomy, Babylonian star catalogues, Bayer designation, Beryllium, Beta particle, Betelgeuse, Binary star, Binding energy, Black dwarf, Black hole, ... Expand index (360 more) »
- Stars
Abd al-Rahman al-Sufi
ʿAbd al-Raḥmān al-Ṣūfī (عبدالرحمن الصوفی; 7 December 90325 May 986) was a Persian Muslim astronomer.
See Star and Abd al-Rahman al-Sufi
Absolute magnitude
In astronomy, absolute magnitude is a measure of the luminosity of a celestial object on an inverse logarithmic astronomical magnitude scale.
See Star and Absolute magnitude
Achernar
Achernar is the brightest star in the constellation of Eridanus and the ninth-brightest in the night sky.
Age of the universe
In physical cosmology, the age of the universe is the time elapsed since the Big Bang. Star and age of the universe are concepts in astronomy.
See Star and Age of the universe
Akkadian language
Akkadian (translit)John Huehnergard & Christopher Woods, "Akkadian and Eblaite", The Cambridge Encyclopedia of the World's Ancient Languages.
See Star and Akkadian language
Al-Andalus
Al-Andalus was the Muslim-ruled area of the Iberian Peninsula.
Al-Biruni
Abu Rayhan Muhammad ibn Ahmad al-Biruni (ابوریحان بیرونی; أبو الريحان البيروني; 973after 1050), known as al-Biruni, was a Khwarazmian Iranian scholar and polymath during the Islamic Golden Age.
Albert A. Michelson
Albert Abraham Michelson FFRS FRSE (surname pronunciation anglicized as "Michael-son", December 19, 1852 – May 9, 1931) was a Prussian-born American physicist of Jewish descent, known for his work on measuring the speed of light and especially for the Michelson–Morley experiment.
See Star and Albert A. Michelson
Algol
Algol, designated Beta Persei (β Persei, abbreviated Beta Per, β Per), known colloquially as the Demon Star, is a bright multiple star in the constellation of Perseus and one of the first non-nova variable stars to be discovered.
See Star and Algol
Algol paradox
In stellar astronomy, the Algol paradox is a paradoxical situation when elements of a binary star seem to evolve in discord with the established theories of stellar evolution. Star and Algol paradox are stellar astronomy.
Ali ibn Ridwan
Abu'l Hassan Ali ibn Radwan Al-Misri (c. 988 - c. 1061) was an Arab of Egyptian origin who was a physician, astrologer and astronomer, born in Giza. He was a commentator on ancient Greek medicine, and in particular on Galen; his commentary on Galen's Ars Parva was translated by Gerardo Cremonese.
Alnilam
Alnilam is the central star of Orion's Belt in the equatorial constellation of Orion.
See Star and Alnilam
Alpha particle
Alpha particles, also called alpha rays or alpha radiation, consist of two protons and two neutrons bound together into a particle identical to a helium-4 nucleus.
Altair
Altair is the brightest star in the constellation of Aquila and the twelfth-brightest star in the night sky.
See Star and Altair
Ancient Greece
Ancient Greece (Hellás) was a northeastern Mediterranean civilization, existing from the Greek Dark Ages of the 12th–9th centuries BC to the end of classical antiquity, that comprised a loose collection of culturally and linguistically related city-states and other territories.
Ancient Greek astronomy
Ancient Greek astronomy is the astronomy written in the Greek language during classical antiquity.
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Ancient Greek philosophy
Ancient Greek philosophy arose in the 6th century BC.
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Ancient Greek religion
Religious practices in ancient Greece encompassed a collection of beliefs, rituals, and mythology, in the form of both popular public religion and cult practices.
See Star and Ancient Greek religion
Andromeda Galaxy
The Andromeda Galaxy is a barred spiral galaxy and is the nearest major galaxy to the Milky Way.
Angelo Secchi
Angelo Secchi (28 June 1818 – 26 February 1878) was an Italian Catholic priest and astronomer from the Italian region of Emilia.
Angular diameter
The angular diameter, angular size, apparent diameter, or apparent size is an angular distance describing how large a sphere or circle appears from a given point of view.
Angular momentum
Angular momentum (sometimes called moment of momentum or rotational momentum) is the rotational analog of linear momentum.
Annie Jump Cannon
Annie Jump Cannon (December 11, 1863 – April 13, 1941) was an American astronomer whose cataloging work was instrumental in the development of contemporary stellar classification.
See Star and Annie Jump Cannon
Apparent magnitude
Apparent magnitude is a measure of the brightness of a star or other astronomical object.
See Star and Apparent magnitude
Arabic
Arabic (اَلْعَرَبِيَّةُ, or عَرَبِيّ, or) is a Central Semitic language of the Afroasiatic language family spoken primarily in the Arab world.
See Star and Arabic
Aristyllus
Aristyllus (Ἀρίστυλλος; fl. c. 261 BC) was a Greek astronomer, presumably of the school of Timocharis (c. 300 BC).
Asterisk
The asterisk, from Late Latin asteriscus, from Ancient Greek ἀστερίσκος,, "little star", is a typographical symbol.
Asterism (astronomy)
An asterism is an observed pattern or group of stars in the sky.
See Star and Asterism (astronomy)
Asteroid
An asteroid is a minor planet—an object that is neither a true planet nor an identified comet— that orbits within the inner Solar System.
Astrology
Astrology is a range of divinatory practices, recognized as pseudoscientific since the 18th century, that propose that information about human affairs and terrestrial events may be discerned by studying the apparent positions of celestial objects.
Astrometry
Astrometry is a branch of astronomy that involves precise measurements of the positions and movements of stars and other celestial bodies.
Astronomer
An astronomer is a scientist in the field of astronomy who focuses their studies on a specific question or field outside the scope of Earth.
Astronomical constant
An astronomical constant is any of several physical constants used in astronomy.
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Astronomical spectroscopy
Astronomical spectroscopy is the study of astronomy using the techniques of spectroscopy to measure the spectrum of electromagnetic radiation, including visible light, ultraviolet, X-ray, infrared and radio waves that radiate from stars and other celestial objects.
See Star and Astronomical spectroscopy
Astronomical unit
The astronomical unit (symbol: au, or AU) is a unit of length defined to be exactly equal to.
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Astronomy in the medieval Islamic world
Medieval Islamic astronomy comprises the astronomical developments made in the Islamic world, particularly during the Islamic Golden Age (9th–13th centuries), and mostly written in the Arabic language.
See Star and Astronomy in the medieval Islamic world
Asymptotic giant branch
The asymptotic giant branch (AGB) is a region of the Hertzsprung–Russell diagram populated by evolved cool luminous stars.
See Star and Asymptotic giant branch
Atomic nucleus
The atomic nucleus is the small, dense region consisting of protons and neutrons at the center of an atom, discovered in 1911 by Ernest Rutherford based on the 1909 Geiger–Marsden gold foil experiment.
Avempace
Abū Bakr Muḥammad ibn Yaḥyà ibn aṣ-Ṣā’igh at-Tūjībī ibn Bājja (أبو بكر محمد بن يحيى بن الصائغ التجيبي بن باجة), best known by his Latinised name Avempace (– 1138), was an Andalusi polymath, whose writings include works regarding astronomy, physics, and music, as well as philosophy, medicine, botany, and poetry.
Babylon
Babylon was an ancient city located on the lower Euphrates river in southern Mesopotamia, within modern-day Hillah, Iraq, about 85 kilometers (55 miles) south of modern day Baghdad.
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Babylonian astronomy
Babylonian astronomy was the study or recording of celestial objects during the early history of Mesopotamia.
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Babylonian star catalogues
Babylonian astronomy collated earlier observations and divinations into sets of Babylonian star catalogues, during and after the Kassite rule over Babylonia.
See Star and Babylonian star catalogues
Bayer designation
A Bayer designation is a stellar designation in which a specific star is identified by a Greek or Latin letter followed by the genitive form of its parent constellation's Latin name.
See Star and Bayer designation
Beryllium
Beryllium is a chemical element; it has symbol Be and atomic number 4.
Beta particle
A beta particle, also called beta ray or beta radiation (symbol β), is a high-energy, high-speed electron or positron emitted by the radioactive decay of an atomic nucleus during the process of beta decay.
Betelgeuse
Betelgeuse is a red supergiant star in the constellation of Orion.
Binary star
A binary star or binary star system is a system of two stars that are gravitationally bound to and in orbit around each other.
Binding energy
In physics and chemistry, binding energy is the smallest amount of energy required to remove a particle from a system of particles or to disassemble a system of particles into individual parts.
Black dwarf
A black dwarf is a theoretical stellar remnant, specifically a white dwarf that has cooled sufficiently to no longer emit significant heat or light.
Black hole
A black hole is a region of spacetime where gravity is so strong that nothing, not even light and other electromagnetic waves, is capable of possessing enough energy to escape it. Star and black hole are concepts in astronomy.
Blue dwarf (red-dwarf stage)
A blue dwarf is a predicted class of star that develops from a red dwarf after it has exhausted much of its hydrogen fuel supply.
See Star and Blue dwarf (red-dwarf stage)
Blue straggler
A blue straggler is a type of star that is more luminous and bluer than expected.
Blue supergiant
A blue supergiant (BSG) is a hot, luminous star, often referred to as an OB supergiant.
Bok globule
In astronomy, Bok globules are isolated and relatively small dark nebulae containing dense cosmic dust and gas from which star formation may take place.
Brightness
Brightness is an attribute of visual perception in which a source appears to be radiating or reflecting light.
British Library
The British Library is a research library in London that is the national library of the United Kingdom.
Brocchi's Cluster
Brocchi's Cluster (also known as Collinder 399, Cr 399 or Al Sufi's Cluster) is a asterism of 10 stars.
See Star and Brocchi's Cluster
Brown dwarf
Brown dwarfs are substellar objects that have more mass than the biggest gas giant planets, but less than the least massive main-sequence stars.
Business
Business is the practice of making one's living or making money by producing or buying and selling products (such as goods and services).
Cambridge University Press
Cambridge University Press is the university press of the University of Cambridge.
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Canopus
Canopus is the brightest star in the southern constellation of Carina and the second-brightest star in the night sky.
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Carbon
Carbon is a chemical element; it has symbol C and atomic number 6.
See Star and Carbon
Carbon-12
Carbon-12 (12C) is the most abundant of the two stable isotopes of carbon (carbon-13 being the other), amounting to 98.93% of element carbon on Earth; its abundance is due to the triple-alpha process by which it is created in stars.
Carbon-burning process
The carbon-burning process or carbon fusion is a set of nuclear fusion reactions that take place in the cores of massive stars (at least 8 \beginsmallmatrixM_\odot\endsmallmatrix at birth) that combines carbon into other elements.
See Star and Carbon-burning process
Cataclysmic variable star
In astronomy, cataclysmic variable stars (CVs) are stars which irregularly increase in brightness by a large factor, then drop back down to a quiescent state.
See Star and Cataclysmic variable star
Catalysis
Catalysis is the increase in rate of a chemical reaction due to an added substance known as a catalyst.
Cecilia Payne-Gaposchkin
Cecilia Payne-Gaposchkin (born Cecilia Helena Payne; –) was a British-born American astronomer and astrophysicist.
See Star and Cecilia Payne-Gaposchkin
Celestial navigation
Celestial navigation, also known as astronavigation, is the practice of position fixing using stars and other celestial bodies that enables a navigator to accurately determine their actual current physical position in space or on the surface of the Earth without relying solely on estimated positional calculations, commonly known as dead reckoning.
See Star and Celestial navigation
Celestial sphere
In astronomy and navigation, the celestial sphere is an abstract sphere that has an arbitrarily large radius and is concentric to Earth.
Celestial spheres
The celestial spheres, or celestial orbs, were the fundamental entities of the cosmological models developed by Plato, Eudoxus, Aristotle, Ptolemy, Copernicus, and others.
See Star and Celestial spheres
Centaurus (journal)
Centaurus.
See Star and Centaurus (journal)
Centre de données astronomiques de Strasbourg
The Centre de Données astronomiques de Strasbourg (CDS; English translation: Strasbourg Astronomical Data Centre) is a data centre which collects and distributes astronomical information.
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Centre for Astrophysics and Supercomputing
The Centre for Astrophysics and Supercomputing (CAS) is a research centre located at the Swinburne University in Melbourne, Australia.
See Star and Centre for Astrophysics and Supercomputing
Cepheid variable
A Cepheid variable is a type of variable star that pulsates radially, varying in both diameter and temperature.
Chemical element
A chemical element is a chemical substance that cannot be broken down into other substances by chemical reactions.
Chemically peculiar star
In astrophysics, chemically peculiar stars (CP stars) are stars with distinctly unusual metal abundances, at least in their surface layers.
See Star and Chemically peculiar star
Chinese astronomy
Astronomy in China has a long history stretching from the Shang dynasty, being refined over a period of more than 3,000 years.
See Star and Chinese astronomy
Chromium
Chromium is a chemical element; it has symbol Cr and atomic number 24.
Chromosphere
A chromosphere ("sphere of color") is the second layer of a star's atmosphere, located above the photosphere and below the solar transition region and corona.
Civilization
A civilization (civilisation) is any complex society characterized by the development of the state, social stratification, urbanization, and symbolic systems of communication beyond signed or spoken languages (namely, writing systems and graphic arts).
CNO cycle
The CNO cycle (for carbon–nitrogen–oxygen; sometimes called Bethe–Weizsäcker cycle after Hans Albrecht Bethe and Carl Friedrich von Weizsäcker) is one of the two known sets of fusion reactions by which stars convert hydrogen to helium, the other being the proton–proton chain reaction (p–p cycle), which is more efficient at the Sun's core temperature.
Color index
In astronomy, the color index is a simple numerical expression that determines the color of an object, which in the case of a star gives its temperature.
Common envelope
In astronomy, a common envelope (CE) is gas that contains a binary star system. Star and common envelope are stellar astronomy.
Compact object
In astronomy, the term compact object (or compact star) refers collectively to white dwarfs, neutron stars, and black holes. Star and compact object are concepts in astronomy.
Concentration
In chemistry, concentration is the abundance of a constituent divided by the total volume of a mixture.
Conjunction (astronomy)
In astronomy, a conjunction occurs when two astronomical objects or spacecraft appear to be close to each other in the sky.
See Star and Conjunction (astronomy)
Constellation
A constellation is an area on the celestial sphere in which a group of visible stars forms a perceived pattern or outline, typically representing an animal, mythological subject, or inanimate object. Star and constellation are concepts in astronomy.
Contact binary
In astronomy, a contact binary is a binary star system whose component stars are so close that they touch each other or have merged to share their gaseous envelopes.
Convection
Convection is single or multiphase fluid flow that occurs spontaneously due to the combined effects of material property heterogeneity and body forces on a fluid, most commonly density and gravity (see buoyancy).
Convection zone
A convection zone, convective zone or convective region of a star is a layer which is unstable due to convection.
Coronal loop
In solar physics, a coronal loop is a well-defined arch-like structure in the Sun's atmosphere made up of relatively dense plasma confined and isolated from the surrounding medium by magnetic flux tubes.
Cosmic distance ladder
The cosmic distance ladder (also known as the extragalactic distance scale) is the succession of methods by which astronomers determine the distances to celestial objects. Star and cosmic distance ladder are concepts in astronomy.
See Star and Cosmic distance ladder
Cosmic dust
Cosmic dustalso called extraterrestrial dust, space dust, or star dustis dust that occurs in outer space or has fallen onto Earth.
Cosmology in the Muslim world
Islamic cosmology is the cosmology of Islamic societies.
See Star and Cosmology in the Muslim world
Cosmos Redshift 7
Cosmos Redshift 7 (also known as COSMOS Redshift 7, Galaxy Cosmos Redshift 7, Galaxy CR7 or CR7) is a high-redshift Lyman-alpha emitter galaxy.
See Star and Cosmos Redshift 7
Crab Nebula
The Crab Nebula (catalogue designations M1, NGC 1952, Taurus A) is a supernova remnant and pulsar wind nebula in the constellation of Taurus.
Degenerate matter
Degenerate matter occurs when the Pauli exclusion principle significantly alters a state of matter at low temperature.
See Star and Degenerate matter
Democritus
Democritus (Δημόκριτος, Dēmókritos, meaning "chosen of the people"; –) was an Ancient Greek pre-Socratic philosopher from Abdera, primarily remembered today for his formulation of an atomic theory of the universe.
Density
Density (volumetric mass density or specific mass) is a substance's mass per unit of volume.
See Star and Density
Deuterium
Deuterium (hydrogen-2, symbol H or D, also known as heavy hydrogen) is one of two stable isotopes of hydrogen (the other is protium, or hydrogen-1).
Divination
Divination is the attempt to gain insight into a question or situation by way of an occultic ritual or practice.
Doppler effect
The Doppler effect (also Doppler shift) is the change in the frequency of a wave in relation to an observer who is moving relative to the source of the wave.
Dredge-up
A dredge-up is any one of several stages in the evolution of some stars.
Dynamo theory
In physics, the dynamo theory proposes a mechanism by which a celestial body such as Earth or a star generates a magnetic field.
Ecliptic
The ecliptic or ecliptic plane is the orbital plane of Earth around the Sun.
Edmond Halley
Edmond (or Edmund) Halley (–) was an English astronomer, mathematician and physicist.
Edward Charles Pickering
Edward Charles Pickering (July 19, 1846 – February 3, 1919) was an American astronomer and physicist and the older brother of William Henry Pickering.
See Star and Edward Charles Pickering
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. Star and effective temperature are concepts in astronomy and stellar astronomy.
See Star and Effective temperature
Egyptian astronomy
Egyptian astronomy began in prehistoric times, in the Predynastic Period.
See Star and Egyptian astronomy
Electromagnetic radiation
In physics, electromagnetic radiation (EMR) consists of waves of the electromagnetic (EM) field, which propagate through space and carry momentum and electromagnetic radiant energy.
See Star and Electromagnetic radiation
Electromagnetic spectrum
The electromagnetic spectrum is the full range of electromagnetic radiation, organized by frequency or wavelength.
See Star and Electromagnetic spectrum
Electron capture
Electron capture (K-electron capture, also K-capture, or L-electron capture, L-capture) is a process in which the proton-rich nucleus of an electrically neutral atom absorbs an inner atomic electron, usually from the K or L electron shells.
Electronvolt
In physics, an electronvolt (symbol eV), also written electron-volt and electron volt, is the measure of an amount of kinetic energy gained by a single electron accelerating through an electric potential difference of one volt in vacuum.
Energy flux
Energy flux is the rate of transfer of energy through a surface.
Epicurus
Epicurus (Ἐπίκουρος; 341–270 BC) was an ancient Greek philosopher and sage who founded Epicureanism, a highly influential school of philosophy.
Epsilon Indi
Epsilon Indi, Latinized from ε Indi, is a star system located at a distance of approximately 12 light-years from Earth in the southern constellation of Indus.
Equatorial bulge
An equatorial bulge is a difference between the equatorial and polar diameters of a planet, due to the centrifugal force exerted by the rotation about the body's axis.
Esther
Esther, originally Hadassah, is the eponymous heroine of the Book of Esther in the Hebrew Bible.
See Star and Esther
Eta Carinae
Eta Carinae (η Carinae, abbreviated to η Car), formerly known as Eta Argus, is a stellar system containing at least two stars with a combined luminosity greater than five million times that of the Sun, located around distant in the constellation Carina.
European Space Agency
The European Space Agency (ESA) is a 22-member intergovernmental body devoted to space exploration.
See Star and European Space Agency
Exoplanet
An exoplanet or extrasolar planet is a planet outside the Solar System. Star and exoplanet are concepts in astronomy.
Extinction (astronomy)
In astronomy, extinction is the absorption and scattering of electromagnetic radiation by dust and gas between an emitting astronomical object and the observer. Star and extinction (astronomy) are concepts in astronomy.
See Star and Extinction (astronomy)
Fairfield University
Fairfield University is a private Jesuit university in Fairfield, Connecticut.
See Star and Fairfield University
Fakhr al-Din al-Razi
Fakhr al-Dīn al-Rāzī (فخر الدين الرازي) or Fakhruddin Razi (فخر الدين رازی) (1149 or 1150 – 1209), often known by the sobriquet Sultan of the Theologians, was an influential Iranian and Muslim polymath, scientist and one of the pioneers of inductive logic.
See Star and Fakhr al-Din al-Razi
First-magnitude star
First-magnitude stars are the brightest stars in the night sky, with apparent magnitudes lower (i.e. brighter) than +1.50. Star and First-magnitude star are stellar astronomy.
See Star and First-magnitude star
Fixed stars
In astronomy, the fixed stars (stellae fixae) are the luminary points, mainly stars, that appear not to move relative to one another against the darkness of the night sky in the background. Star and fixed stars are stellar astronomy.
Flamsteed designation
A Flamsteed designation is a combination of a number and constellation name that uniquely identifies most naked eye stars in the modern constellations visible from southern England.
See Star and Flamsteed designation
Flare star
A flare star is a variable star that can undergo unpredictable dramatic increases in brightness for a few minutes.
Frequency
Frequency (symbol f), most often measured in hertz (symbol: Hz), is the number of occurrences of a repeating event per unit of time.
Friedrich Georg Wilhelm von Struve
Friedrich Georg Wilhelm von Struve (Василий Яковлевич Струве, trans. Vasily Yakovlevich Struve; 15 April 1793 –) was a Baltic German astronomer and geodesist.
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Friedrich Wilhelm Bessel
Friedrich Wilhelm Bessel (22 July 1784 – 17 March 1846) was a German astronomer, mathematician, physicist, and geodesist.
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Fusor (astronomy)
Fusor is a proposed term for an astronomical object which is capable of core fusion.
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G-type main-sequence star
A G-type main-sequence star (spectral type: G-V), also often, and imprecisely, called a yellow dwarf, or G star, is a main-sequence star (luminosity class V) of spectral type G. Such a star has about 0.9 to 1.1 solar masses and an effective temperature between about.
See Star and G-type main-sequence star
Galactic Center
The Galactic Center is the barycenter of the Milky Way and a corresponding point on the rotational axis of the galaxy.
Galactic disc
A galactic disc (or galactic disk) is a component of disc galaxies, such as spiral galaxies like the Milky Way and lenticular galaxies.
Galaxy
A galaxy is a system of stars, stellar remnants, interstellar gas, dust, and dark matter bound together by gravity. Star and galaxy are concepts in astronomy.
See Star and Galaxy
Galaxy cluster
A galaxy cluster, or a cluster of galaxies, is a structure that consists of anywhere from hundreds to thousands of galaxies that are bound together by gravity, with typical masses ranging from 1014 to 1015 solar masses.
Gamma ray
A gamma ray, also known as gamma radiation (symbol), is a penetrating form of electromagnetic radiation arising from the radioactive decay of atomic nuclei.
Gas giant
A gas giant is a giant planet composed mainly of hydrogen and helium.
Gaussian units
Gaussian units constitute a metric system of physical units.
Geminiano Montanari
Geminiano Montanari (1 June 1633 – 13 October 1687) was an Italian astronomer, lens-maker, and proponent of the experimental approach to science.
See Star and Geminiano Montanari
Giant star
A giant star has a substantially larger radius and luminosity than a main-sequence (or dwarf) star of the same surface temperature.
Giordano Bruno
Giordano Bruno (Iordanus Brunus Nolanus; born Filippo Bruno, January or February 1548 – 17 February 1600) was an Italian philosopher, poet, alchemist, astronomer, cosmological theorist, and esotericist.
Gliese 65
Gliese 65, also known as Luyten 726-8, is a binary star system that is one of Earth's nearest neighbors, at from Earth in the constellation Cetus.
Globular cluster
A globular cluster is a spheroidal conglomeration of stars that is bound together by gravity, with a higher concentration of stars towards its center.
Glossary of astronomy
This glossary of astronomy is a list of definitions of terms and concepts relevant to astronomy and cosmology, their sub-disciplines, and related fields.
See Star and Glossary of astronomy
Gradient
In vector calculus, the gradient of a scalar-valued differentiable function f of several variables is the vector field (or vector-valued function) \nabla f whose value at a point p gives the direction and the rate of fastest increase.
Gravitational collapse
Gravitational collapse is the contraction of an astronomical object due to the influence of its own gravity, which tends to draw matter inward toward the center of gravity.
See Star and Gravitational collapse
Gravitational constant
The gravitational constant is an empirical physical constant involved in the calculation of gravitational effects in Sir Isaac Newton's law of universal gravitation and in Albert Einstein's theory of general relativity.
See Star and Gravitational constant
Gravitational lens
A gravitational lens is matter, such as a cluster of galaxies or a point particle, that bends light from a distant source as it travels toward an observer. Star and gravitational lens are concepts in astronomy.
See Star and Gravitational lens
Gravitational microlensing
Gravitational microlensing is an astronomical phenomenon caused by the gravitational lens effect.
See Star and Gravitational microlensing
Greek language
Greek (Elliniká,; Hellēnikḗ) is an independent branch of the Indo-European family of languages, native to Greece, Cyprus, Italy (in Calabria and Salento), southern Albania, and other regions of the Balkans, the Black Sea coast, Asia Minor, and the Eastern Mediterranean.
Greek mythology
Greek mythology is the body of myths originally told by the ancient Greeks, and a genre of ancient Greek folklore, today absorbed alongside Roman mythology into the broader designation of classical mythology.
Gregorian calendar
The Gregorian calendar is the calendar used in most parts of the world.
See Star and Gregorian calendar
H II region
An H II region or HII region is a region of interstellar atomic hydrogen that is ionized.
Hayashi track
The Hayashi track is a luminosity–temperature relationship obeyed by infant stars of less than in the pre-main-sequence phase (PMS phase) of stellar evolution.
HD 140283
HD 140283 (also known as the Methuselah star) is a metal-poor subgiant star about 200 light years away from the Earth in the constellation Libra, near the boundary with Ophiuchus in the Milky Way Galaxy.
Heliosphere
The heliosphere is the magnetosphere, astrosphere, and outermost atmospheric layer of the Sun.
Helium
Helium (from lit) is a chemical element; it has symbol He and atomic number 2.
See Star and Helium
Helium flash
A helium flash is a very brief thermal runaway nuclear fusion of large quantities of helium into carbon through the triple-alpha process in the core of low-mass stars (between 0.8 solar masses and 2.0) during their red giant phase.
Helium-3
Helium-3 (3He see also helion) is a light, stable isotope of helium with two protons and one neutron.
Helium-4
Helium-4 is a stable isotope of the element helium.
Henyey track
The Henyey track is a path taken by pre-main-sequence stars with masses greater than 0.5 solar masses in the Hertzsprung–Russell diagram after the end of the Hayashi track.
Herbig Ae/Be star
A Herbig Ae/Be star (HAeBe) is a pre-main-sequence star – a young (.
See Star and Herbig Ae/Be star
Herbig–Haro object
Herbig–Haro (HH) objects are bright patches of nebulosity associated with newborn stars.
See Star and Herbig–Haro object
Hertzsprung–Russell diagram
The Hertzsprung–Russell diagram (abbreviated as H–R diagram, HR diagram or HRD) is a scatter plot of stars showing the relationship between the stars' absolute magnitudes or luminosities and their stellar classifications or effective temperatures. Star and Hertzsprung–Russell diagram are concepts in astronomy.
See Star and Hertzsprung–Russell diagram
Hipparchus
Hipparchus (Ἵππαρχος, Hipparkhos; BC) was a Greek astronomer, geographer, and mathematician.
Horizontal branch
The horizontal branch (HB) is a stage of stellar evolution that immediately follows the red-giant branch in stars whose masses are similar to the Sun's.
See Star and Horizontal branch
Human eye
The human eye is an organ of the sensory nervous system that reacts to visible light and allows the use of visual information for various purposes including seeing things, keeping balance, and maintaining circadian rhythm.
Hydrogen
Hydrogen is a chemical element; it has symbol H and atomic number 1.
Hydrogen line
The hydrogen line, 21 centimeter line, or H I line is a spectral line that is created by a change in the energy state of solitary, electrically neutral hydrogen atoms.
Hydrostatic equilibrium
In fluid mechanics, hydrostatic equilibrium (hydrostatic balance, hydrostasy) is the condition of a fluid or plastic solid at rest, which occurs when external forces, such as gravity, are balanced by a pressure-gradient force. Star and hydrostatic equilibrium are concepts in astronomy.
See Star and Hydrostatic equilibrium
Hypergiant
A hypergiant (luminosity class 0 or Ia+) is a very rare type of star that has an extremely high luminosity, mass, size and mass loss because of its extreme stellar winds.
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.
See Star and IAU Working Group on Star Names
Inanna
Inanna is the ancient Mesopotamian goddess of love, war, and fertility.
See Star and Inanna
Infrared
Infrared (IR; sometimes called infrared light) is electromagnetic radiation (EMR) with wavelengths longer than that of visible light but shorter than microwaves.
Interacting galaxy
Interacting galaxies (colliding galaxies) are galaxies whose gravitational fields result in a disturbance of one another.
See Star and Interacting galaxy
Interferometry
Interferometry is a technique which uses the interference of superimposed waves to extract information.
International Astronomical Union
The International Astronomical Union (IAU; Union astronomique internationale, UAI) is an international non-governmental organization (INGO) with the objective of advancing astronomy in all aspects, including promoting astronomical research, outreach, education, and development through global cooperation.
See Star and International Astronomical Union
International System of Units
The International System of Units, internationally known by the abbreviation SI (from French Système international d'unités), is the modern form of the metric system and the world's most widely used system of measurement.
See Star and International System of Units
Interstellar medium
The interstellar medium (ISM) is the matter and radiation that exists in the space between the star systems in a galaxy. Star and interstellar medium are concepts in astronomy.
See Star and Interstellar medium
Inverse beta decay
In nuclear and particle physics, inverse beta decay, commonly abbreviated to IBD, is a nuclear reaction involving an electron antineutrino scattering off a proton, creating a positron and a neutron.
See Star and Inverse beta decay
Ion
An ion is an atom or molecule with a net electrical charge.
See Star and Ion
Isaac Newton
Sir Isaac Newton (25 December 1642 – 20 March 1726/27) was an English polymath active as a mathematician, physicist, astronomer, alchemist, theologian, and author who was described in his time as a natural philosopher.
Isis (journal)
Isis is a quarterly peer-reviewed academic journal published by the University of Chicago Press.
Islamic calendar
The Hijri calendar (translit), or Arabic calendar also known in English as the Muslim calendar and Islamic calendar, is a lunar calendar consisting of 12 lunar months in a year of 354 or 355 days.
Isotopes of beryllium
Beryllium (4Be) has 11 known isotopes and 3 known isomers, but only one of these isotopes is stable and a primordial nuclide.
See Star and Isotopes of beryllium
Isotopes of hydrogen
Hydrogen (1H) has three naturally occurring isotopes, sometimes denoted,, and.
See Star and Isotopes of hydrogen
Jeans instability
The Jeans instability is a concept in astrophysics that describes an instability that leads to the gravitational collapse of a cloud of gas or dust.
See Star and Jeans instability
Johann Bayer
Johann Bayer (1572 – 7 March 1625) was a German lawyer and uranographer (celestial cartographer).
John Flamsteed
John Flamsteed (19 August 1646 – 31 December 1719) was an English astronomer and the first Astronomer Royal.
John Herschel
Sir John Frederick William Herschel, 1st Baronet (7 March 1792 – 11 May 1871) was an English polymath active as a mathematician, astronomer, chemist, inventor and experimental photographer who invented the blueprint and did botanical work.
Joseph von Fraunhofer
Joseph Ritter von Fraunhofer (6 March 1787 – 7 June 1826) was a German physicist and optical lens manufacturer.
See Star and Joseph von Fraunhofer
Jupiter
Jupiter is the fifth planet from the Sun and the largest in the Solar System.
See Star and Jupiter
Karl Schwarzschild
Karl Schwarzschild (9 October 1873 – 11 May 1916) was a German physicist and astronomer.
See Star and Karl Schwarzschild
Kassites
The Kassites were people of the ancient Near East, who controlled Babylonia after the fall of the Old Babylonian Empire and until (short chronology).
Kelvin
The kelvin, symbol K, is the base unit of measurement for temperature in the International System of Units (SI).
See Star and Kelvin
Large Magellanic Cloud
The Large Magellanic Cloud (LMC) is a dwarf galaxy and satellite galaxy of the Milky Way.
See Star and Large Magellanic Cloud
Latin
Latin (lingua Latina,, or Latinum) is a classical language belonging to the Italic branch of the Indo-European languages.
See Star and Latin
Latitude
In geography, latitude is a coordinate that specifies the north–south position of a point on the surface of the Earth or another celestial body.
Library of Congress
The Library of Congress (LOC) is a research library in Washington, D.C. that serves as the library and research service of the U.S. Congress and the de facto national library of the United States.
See Star and Library of Congress
Light-year
A light-year, alternatively spelled light year (ly or lyr), is a unit of length used to express astronomical distances and is equal to exactly 9,460,730,472,580.8 km (Scientific notation: 9.4607304725808 × 1012 km), which is approximately 5.88 trillion mi. Star and light-year are concepts in astronomy.
Limb darkening
Limb darkening is an optical effect seen in stars (including the Sun) and planets, where the central part of the disk appears brighter than the edge, or limb.
List of Arabic star names
This is a list of Arabic star names.
See Star and List of Arabic star names
List of most luminous stars
This is a list of stars arranged by their absolute magnitude – their intrinsic stellar luminosity.
See Star and List of most luminous stars
List of most massive stars
This is a list of the most massive stars that have been discovered, in solar mass units.
See Star and List of most massive stars
List of nearest stars
This list covers all known stars, white dwarfs, brown dwarfs, and sub-brown dwarfs within of the Sun.
See Star and List of nearest stars
List of proper names of stars
These names of stars that have either been approved by the International Astronomical Union or which have been in somewhat recent use.
See Star and List of proper names of stars
Lithium
Lithium is a chemical element; it has symbol Li and atomic number 3.
See Star and Lithium
Local Group
The Local Group is the galaxy group that includes the Milky Way, where Earth is located.
Logarithmic scale
A logarithmic scale (or log scale) is a method used to display numerical data that spans a broad range of values, especially when there are significant differences between the magnitudes of the numbers involved.
See Star and Logarithmic scale
Luminosity
Luminosity is an absolute measure of radiated electromagnetic energy (light) per unit time, and is synonymous with the radiant power emitted by a light-emitting object.
Luminous blue variable
Luminous blue variables (LBVs) are massive evolved stars that show unpredictable and sometimes dramatic variations in their spectra and brightness.
See Star and Luminous blue variable
Lunar eclipse
A lunar eclipse is an astronomical event that occurs when the Moon moves into the Earth's shadow, causing the Moon to be darkened.
MACS J1149 Lensed Star 1
MACS J1149 Lensed Star 1, also known as Icarus,Other names include LS1, MACS J1149 LS1, MACS J1149 Lensed Star 1 (LS1) and MACS J1149+2223 Lensed Star 1 is a blue supergiant star observed through a gravitational lens.
See Star and MACS J1149 Lensed Star 1
Magnetic field
A magnetic field (sometimes called B-field) is a physical field that describes the magnetic influence on moving electric charges, electric currents, and magnetic materials.
Main sequence
In astronomy, the main sequence is a classification of stars which appear on plots of stellar color versus brightness as a continuous and distinctive band. Star and main sequence are concepts in astronomy.
Main sequence turnoff
The turnoff point for a star refers to the point on the Hertzsprung–Russell diagram where it leaves the main sequence after its main fuel is exhaustedthe main sequence turnoff.
See Star and Main sequence turnoff
Mars
Mars is the fourth planet from the Sun.
See Star and Mars
Mass
Mass is an intrinsic property of a body.
See Star and Mass
Mass–energy equivalence
In physics, mass–energy equivalence is the relationship between mass and energy in a system's rest frame, where the two quantities differ only by a multiplicative constant and the units of measurement.
See Star and Mass–energy equivalence
Maunder Minimum
The Maunder Minimum, also known as the "prolonged sunspot minimum", was a period around 1645 to 1715 during which sunspots became exceedingly rare.
Mercury (planet)
Mercury is the first planet from the Sun and the smallest in the Solar System.
Mesopotamia
Mesopotamia is a historical region of West Asia situated within the Tigris–Euphrates river system, in the northern part of the Fertile Crescent.
Messier 100
Messier 100 (also known as NGC 4321 or the Mirror Galaxy) is a grand design intermediate spiral galaxy in the southern part of the mildly northern Coma Berenices.
Messier 87
Messier 87 (also known as Virgo A or NGC 4486, generally abbreviated to M87) is a supergiant elliptical galaxy in the constellation Virgo that contains several trillion stars.
Metallicity
In astronomy, metallicity is the abundance of elements present in an object that are heavier than hydrogen and helium. Star and metallicity are concepts in astronomy and stellar astronomy.
Milky Way
The Milky Way is the galaxy that includes the Solar System, with the name describing the galaxy's appearance from Earth: a hazy band of light seen in the night sky formed from stars that cannot be individually distinguished by the naked eye.
Minute and second of arc
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.
See Star and Minute and second of arc
Mira variable
Mira variables (named for the prototype star Mira) are a class of pulsating stars characterized by very red colours, pulsation periods longer than 100 days, and amplitudes greater than one magnitude in infrared and 2.5 magnitude at visual wavelengths.
Mizar
Mizar is a second-magnitude star in the handle of the Big Dipper asterism in the constellation of Ursa Major.
See Star and Mizar
Molecular cloud
A molecular cloud, sometimes called a stellar nursery (if star formation is occurring within), is a type of interstellar cloud, the density and size of which permit absorption nebulae, the formation of molecules (most commonly molecular hydrogen, H2), and the formation of H II regions. Star and molecular cloud are concepts in astronomy.
Monthly Notices of the Royal Astronomical Society
Monthly Notices of the Royal Astronomical Society (MNRAS) is a peer-reviewed scientific journal in astronomy, astrophysics and related fields.
See Star and Monthly Notices of the Royal Astronomical Society
Moon
The Moon is Earth's only natural satellite.
See Star and Moon
Mount Wilson Observatory
The Mount Wilson Observatory (MWO) is an astronomical observatory in Los Angeles County, California, United States.
See Star and Mount Wilson Observatory
Mu Leonis
Mu Leonis (μ Leonis, abbreviated Mu Leo, μ Leo), also named Rasalas, is a star in the constellation of Leo.
Myth
Myth is a genre of folklore consisting primarily of narratives that play a fundamental role in a society.
See Star and Myth
National and Kapodistrian University of Athens
The National and Kapodistrian University of Athens (NKUA; Εθνικό και Καποδιστριακό Πανεπιστήμιο Αθηνών, Ethnikó kai Kapodistriakó Panepistímio Athinón), usually referred to simply as the University of Athens (UoA), is a public university in Zografou, a suburban town in the Athens agglomeration, Greece.
See Star and National and Kapodistrian University of Athens
Nature (journal)
Nature is a British weekly scientific journal founded and based in London, England.
Nebula
A nebula (cloud, fog;: nebulae, nebulæ, or nebulas) is a distinct luminescent part of interstellar medium, which can consist of ionized, neutral, or molecular hydrogen and also cosmic dust. Star and nebula are concepts in astronomy.
See Star and Nebula
Neon
Neon is a chemical element; it has symbol Ne and atomic number 10.
See Star and Neon
Neon-burning process
The neon-burning process is a set of nuclear fusion reactions that take place in evolved massive stars with at least 8 Solar masses.
See Star and Neon-burning process
Neptune
Neptune is the eighth and farthest known planet from the Sun.
See Star and Neptune
Neutron star
A neutron star is the collapsed core of a massive supergiant star.
New York City Department of Consumer and Worker Protection
The New York City Department of Consumer and Worker Protection (DCWP), formerly the Department of Consumer Affairs (DCA), is a department of the government of New York City.
See Star and New York City Department of Consumer and Worker Protection
NGC 6397
NGC 6397 (also known as Caldwell 86) is a globular cluster in the constellation Ara that was discovered by French astronomer Nicolas-Louis de Lacaille in 1752.
Night sky
The night sky is the nighttime appearance of celestial objects like stars, planets, and the Moon, which are visible in a clear sky between sunset and sunrise, when the Sun is below the horizon.
Nocturnal (instrument)
A nocturnal is an instrument used to determine the local time based on the position of a star in the night sky relative to the pole star.
See Star and Nocturnal (instrument)
Nova
A nova (novae or novas) is a transient astronomical event that causes the sudden appearance of a bright, apparently "new" star (hence the name "nova", Latin for "new") that slowly fades over weeks or months.
See Star and Nova
Nth root
In mathematics, an th root of a number is a number (the root) which, when raised to the power of the positive integer, yields: r^n.
Nuclear fusion
Nuclear fusion is a reaction in which two or more atomic nuclei, usually deuterium and tritium (hydrogen isotopes), combine to form one or more different atomic nuclei and subatomic particles (neutrons or protons).
O-type star
An O-type star is a hot, blue-white star of spectral type O in the Yerkes classification system employed by astronomers.
Observable universe
The observable universe is a ball-shaped region of the universe consisting of all matter that can be observed from Earth or its space-based telescopes and exploratory probes at the present time; the electromagnetic radiation from these objects has had time to reach the Solar System and Earth since the beginning of the cosmological expansion. Star and observable universe are concepts in astronomy.
See Star and Observable universe
Observatory
An observatory is a location used for observing terrestrial, marine, or celestial events.
Occultation
An occultation is an event that occurs when one object is hidden from the observer by another object that passes between them.
Omicron Velorum
Omicron Velorum (ο Vel, ο Velorum) is a star in the constellation Vela.
Opacity
Opacity is the measure of impenetrability to electromagnetic or other kinds of radiation, especially visible light.
See Star and Opacity
Orbital elements
Orbital elements are the parameters required to uniquely identify a specific orbit.
Orion (constellation)
Orion is a prominent set of stars visible during winter in the northern celestial hemisphere.
See Star and Orion (constellation)
Orion Nebula
The Orion Nebula (also known as Messier 42, M42, or NGC 1976) is a diffuse nebula situated in the Milky Way, being south of Orion's Belt in the constellation of Orion, and is known as the middle "star" in the "sword" of Orion.
Orion's Belt
Orion's Belt is an asterism in the constellation of Orion.
Outer space
Outer space (or simply space) is the expanse that exists beyond Earth's atmosphere and between celestial bodies.
Outline of astronomy
The following outline is provided as an overview of and topical guide to astronomy: Astronomy – studies the universe beyond Earth, including its formation and development, and the evolution, physics, chemistry, meteorology, and motion of celestial objects (such as galaxies, planets, etc.) and phenomena that originate outside the atmosphere of Earth (such as the cosmic background radiation).
See Star and Outline of astronomy
Oxygen
Oxygen is a chemical element; it has symbol O and atomic number 8.
See Star and Oxygen
Oxygen-burning process
The oxygen-burning process is a set of nuclear fusion reactions that take place in massive stars that have used up the lighter elements in their cores.
See Star and Oxygen-burning process
Parallax
Parallax is a displacement or difference in the apparent position of an object viewed along two different lines of sight and is measured by the angle or half-angle of inclination between those two lines.
Particle radiation
Particle radiation is the radiation of energy by means of fast-moving subatomic particles.
See Star and Particle radiation
Perseus molecular cloud
The Perseus molecular cloud (Per MCld) is a nearby (~1000 ly) giant molecular cloud in the constellation of Perseus and contains over 10,000 solar masses of gas and dust covering an area of 6 by 2 degrees.
See Star and Perseus molecular cloud
Persians
The Persians--> are an Iranian ethnic group who comprise over half of the population of Iran.
Photoelectric effect
The photoelectric effect is the emission of electrons from a material caused by electromagnetic radiation such as ultraviolet light.
See Star and Photoelectric effect
Photographic magnitude
Photographic magnitude is a measure of the relative brightness of a star or other astronomical object as imaged on a photographic film emulsion with a camera attached to a telescope.
See Star and Photographic magnitude
Photometer
A photometer is an instrument that measures the strength of electromagnetic radiation in the range from ultraviolet to infrared and including the visible spectrum.
Photon
A photon is an elementary particle that is a quantum of the electromagnetic field, including electromagnetic radiation such as light and radio waves, and the force carrier for the electromagnetic force.
See Star and Photon
Photosphere
The photosphere is a star's outer shell from which light is radiated. Star and photosphere are light sources and stellar astronomy.
Planck (spacecraft)
Planck was a space observatory operated by the European Space Agency (ESA) from 2009 to 2013.
See Star and Planck (spacecraft)
Planet
A planet is a large, rounded astronomical body that is generally required to be in orbit around a star, stellar remnant, or brown dwarf, and is not one itself. Star and planet are concepts in astronomy.
See Star and Planet
Planetary nebula
A planetary nebula is a type of emission nebula consisting of an expanding, glowing shell of ionized gas ejected from red giant stars late in their lives.
Planetary system
A planetary system is a set of gravitationally bound non-stellar objects in or out of orbit around a star or star system. Star and planetary system are concepts in astronomy.
Plasma (physics)
Plasma is one of four fundamental states of matter (the other three being solid, liquid, and gas) characterized by the presence of a significant portion of charged particles in any combination of ions or electrons.
Polymath
A polymath (lit; lit) or polyhistor (lit) is an individual whose knowledge spans many different subjects, known to draw on complex bodies of knowledge to solve specific problems.
Positron
The positron or antielectron is the particle with an electric charge of +1e, a spin of 1/2 (the same as the electron), and the same mass as an electron.
Power (physics)
Power is the amount of energy transferred or converted per unit time.
Pre-main-sequence star
A pre-main-sequence star (also known as a PMS star and PMS object) is a star in the stage when it has not yet reached the main sequence.
See Star and Pre-main-sequence star
Pressure gradient
In hydrodynamics and hydrostatics, the pressure gradient (typically of air but more generally of any fluid) is a physical quantity that describes in which direction and at what rate the pressure increases the most rapidly around a particular location.
See Star and Pressure gradient
Procyon
Procyon is the brightest star in the constellation of Canis Minor and usually the eighth-brightest star in the night sky, with an apparent visual magnitude of 0.34.
See Star and Procyon
Proper motion
Proper motion is the astrometric measure of the observed changes in the apparent places of stars or other celestial objects in the sky, as seen from the center of mass of the Solar System, compared to the abstract background of the more distant stars. Star and Proper motion are concepts in astronomy and stellar astronomy.
Proper noun
A proper noun is a noun that identifies a single entity and is used to refer to that entity (Africa; Jupiter; Sarah; Walmart) as distinguished from a common noun, which is a noun that refers to a class of entities (continent, planet, person, corporation) and may be used when referring to instances of a specific class (a continent, another planet, these persons, our corporation).
Proto-Indo-European language
Proto-Indo-European (PIE) is the reconstructed common ancestor of the Indo-European language family.
See Star and Proto-Indo-European language
Proton
A proton is a stable subatomic particle, symbol, H+, or 1H+ with a positive electric charge of +1 e (elementary charge).
See Star and Proton
Proton–proton chain
The proton–proton chain, also commonly referred to as the chain, is one of two known sets of nuclear fusion reactions by which stars convert hydrogen to helium.
See Star and Proton–proton chain
Protoplanetary disk
A protoplanetary disk is a rotating circumstellar disc of dense gas and dust surrounding a young newly formed star, a T Tauri star, or Herbig Ae/Be star.
See Star and Protoplanetary disk
Protostar
A protostar is a very young star that is still gathering mass from its parent molecular cloud.
Proxima Centauri
Proxima Centauri is a small, low-mass star located away from the Sun in the southern constellation of Centaurus.
Ptolemy
Claudius Ptolemy (Πτολεμαῖος,; Claudius Ptolemaeus; AD) was an Alexandrian mathematician, astronomer, astrologer, geographer, and music theorist who wrote about a dozen scientific treatises, three of which were important to later Byzantine, Islamic, and Western European science.
See Star and Ptolemy
Pulsar
A pulsar (from pulsating radio source) is a highly magnetized rotating neutron star that emits beams of electromagnetic radiation out of its magnetic poles.
See Star and Pulsar
QCD matter
Quark matter or QCD matter (quantum chromodynamic) refers to any of a number of hypothetical phases of matter whose degrees of freedom include quarks and gluons, of which the prominent example is quark-gluon plasma.
Quantum mechanics
Quantum mechanics is a fundamental theory that describes the behavior of nature at and below the scale of atoms.
See Star and Quantum mechanics
R Doradus
R Doradus (HD 29712 or P Doradus) is a red giant variable star in the far-southern constellation Dorado, close to the border with Reticulum.
R136
R136 (formerly known as RMC 136 from the Radcliffe Observatory Magellanic Clouds catalogue) is the central concentration of stars in the NGC 2070 star cluster, which lies at the centre of the Tarantula Nebula in the Large Magellanic Cloud.
See Star and R136
Radial velocity
The radial velocity or line-of-sight velocity of a target with respect to an observer is the rate of change of the vector displacement between the two points. Star and radial velocity are concepts in astronomy.
Radiant energy
In physics, and in particular as measured by radiometry, radiant energy is the energy of electromagnetic and gravitational radiation.
Radiation
In physics, radiation is the emission or transmission of energy in the form of waves or particles through space or a material medium.
Radiation pressure
Radiation pressure (also known as light pressure) is mechanical pressure exerted upon a surface due to the exchange of momentum between the object and the electromagnetic field.
See Star and Radiation pressure
Radiation zone
A radiation zone, or radiative region is a layer of a star's interior where energy is primarily transported toward the exterior by means of radiative diffusion and thermal conduction, rather than by convection.
Radio frequency
Radio frequency (RF) is the oscillation rate of an alternating electric current or voltage or of a magnetic, electric or electromagnetic field or mechanical system in the frequency range from around to around.
Radius
In classical geometry, a radius (radii or radiuses) of a circle or sphere is any of the line segments from its center to its perimeter, and in more modern usage, it is also their length.
See Star and Radius
Rare-earth element
The rare-earth elements (REE), also called the rare-earth metals or rare earths or, in context, rare-earth oxides, and sometimes the lanthanides (although scandium and yttrium, which do not belong to this series, are usually included as rare earths), are a set of 17 nearly indistinguishable lustrous silvery-white soft heavy metals.
See Star and Rare-earth element
Red clump
The red clump is a clustering of red giants in the Hertzsprung–Russell diagram at around 5,000 K and absolute magnitude (MV) +0.5, slightly hotter than most red-giant-branch stars of the same luminosity.
Red dwarf
A red dwarf is the smallest kind of star on the main sequence.
Red giant
A red giant is a luminous giant star of low or intermediate mass (roughly 0.3–8 solar masses) in a late phase of stellar evolution.
Red supergiant
Red supergiants (RSGs) are stars with a supergiant luminosity class (Yerkes class I) and a stellar classification K or M. They are the largest stars in the universe in terms of volume, although they are not the most massive or luminous.
Red-giant branch
The red-giant branch (RGB), sometimes called the first giant branch, is the portion of the giant branch before helium ignition occurs in the course of stellar evolution.
Refraction
In physics, refraction is the redirection of a wave as it passes from one medium to another.
Regulation
Regulation is the management of complex systems according to a set of rules and trends.
Richard Bentley
Richard Bentley FRS (27 January 1662 – 14 July 1742) was an English classical scholar, critic, and theologian.
Rigel
Rigel is a blue supergiant star in the constellation of Orion.
See Star and Rigel
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 March equinox to the (hour circle of the) point in question above the Earth.
Roche lobe
In astronomy, the Roche lobe is the region around a star in a binary system within which orbiting material is gravitationally bound to that star.
Roman mythology
Roman mythology is the body of myths of ancient Rome as represented in the literature and visual arts of the Romans, and is a form of Roman folklore.
Rotation
Rotation or rotational motion is the circular movement of an object around a central line, known as axis of rotation.
Sand
Sand is a granular material composed of finely divided mineral particles.
See Star and Sand
Saturn
Saturn is the sixth planet from the Sun and the second-largest in the Solar System, after Jupiter.
See Star and Saturn
Second
The second (symbol: s) is the unit of time in the International System of Units (SI), historically defined as of a day – this factor derived from the division of the day first into 24 hours, then to 60 minutes and finally to 60 seconds each (24 × 60 × 60.
See Star and Second
Self-gravitation
Self-gravity is gravitational force exerted by a system, particularly a celestial body or system of bodies, onto itself.
Semi-major and semi-minor axes
In geometry, the major axis of an ellipse is its longest diameter: a line segment that runs through the center and both foci, with ends at the two most widely separated points of the perimeter.
See Star and Semi-major and semi-minor axes
Sherburne Wesley Burnham
Sherburne Wesley Burnham (December 12, 1838 – March 11, 1921) was an American astronomer.
See Star and Sherburne Wesley Burnham
Shock wave
In physics, a shock wave (also spelled shockwave), or shock, is a type of propagating disturbance that moves faster than the local speed of sound in the medium.
Sidereal time
Sidereal time ("sidereal" pronounced) is a system of timekeeping used especially by astronomers.
Silicon
Silicon is a chemical element; it has symbol Si and atomic number 14.
See Star and Silicon
Silicon-burning process
In astrophysics, silicon burning is a very brief sequence of nuclear fusion reactions that occur in massive stars with a minimum of about 8–11 solar masses.
See Star and Silicon-burning process
Sirius
Sirius is the brightest star in the night sky.
See Star and Sirius
SN 1006
SN 1006 was a supernova that is likely the brightest observed stellar event in recorded history, reaching an estimated −7.5 visual magnitude, and exceeding roughly sixteen times the brightness of Venus.
See Star and SN 1006
SN 1054
SN 1054 was a supernova that was first observed on, and remained visible until.
See Star and SN 1054
SN 185
SN 185 was a transient astronomical event observed in 185 AD, likely a supernova.
See Star and SN 185
Solar calendar
A solar calendar is a calendar whose dates indicate the season or almost equivalently the apparent position of the Sun relative to the stars.
Solar eclipse
A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby obscuring the view of the Sun from a small part of Earth, totally or partially.
Solar flare
A solar flare is a relatively intense, localized emission of electromagnetic radiation in the Sun's atmosphere.
Solar luminosity
The solar luminosity is a unit of radiant flux (power emitted in the form of photons) conventionally used by astronomers to measure the luminosity of stars, galaxies and other celestial objects in terms of the output of the Sun. Star and solar luminosity are stellar astronomy.
Solar mass
The solar mass is a standard unit of mass in astronomy, equal to approximately.
Solar radius
Solar radius is a unit of distance used to express the size of stars in astronomy relative to the Sun. Star and Solar radius are stellar astronomy.
Solar spicule
In solar physics, a spicule, also known as a fibril or mottle, is a dynamic jet of plasma in the Sun's chromosphere about 300 km in diameter.
Solar wind
The solar wind is a stream of charged particles released from the Sun's outermost atmospheric layer, the corona.
Space
Space is a three-dimensional continuum containing positions and directions.
See Star and Space
Space Shuttle
The Space Shuttle is a retired, partially reusable low Earth orbital spacecraft system operated from 1981 to 2011 by the U.S. National Aeronautics and Space Administration (NASA) as part of the Space Shuttle program.
Space.com
Space.com is an online publication focused on space exploration, astronomy, skywatching and entertainment, with editorial teams based in the United States and United Kingdom.
Spectral line
A spectral line is a weaker or stronger region in an otherwise uniform and continuous spectrum.
Spectroscopy
Spectroscopy is the field of study that measures and interprets electromagnetic spectra. Star and Spectroscopy are concepts in astronomy.
Spheroid
A spheroid, also known as an ellipsoid of revolution or rotational ellipsoid, is a quadric surface obtained by rotating an ellipse about one of its principal axes; in other words, an ellipsoid with two equal semi-diameters.
Spiral galaxy
Spiral galaxies form a class of galaxy originally described by Edwin Hubble in his 1936 work The Realm of the Nebulae (pp. 124–151) and, as such, form part of the Hubble sequence.
Stanford Encyclopedia of Philosophy
The Stanford Encyclopedia of Philosophy (SEP) is a freely available online philosophy resource published and maintained by Stanford University, encompassing both an online encyclopedia of philosophy and peer-reviewed original publication.
See Star and Stanford Encyclopedia of Philosophy
Star catalogue
A star catalogue is an astronomical catalogue that lists stars. Star and star catalogue are stellar astronomy.
Star chart
A star chart is a celestial map of the night sky with astronomical objects laid out on a grid system.
Star cluster
Star clusters are large groups of stars held together by self-gravitation.
Star count
Star counts are bookkeeping surveys of stars and the statistical and geometrical methods used to correct the survey data for bias. Star and star count are stellar astronomy.
Star formation
Star formation is the process by which dense regions within molecular clouds in interstellar space, sometimes referred to as "stellar nurseries" or "star-forming regions", collapse and form stars. Star and star formation are concepts in astronomy and stellar astronomy.
Star system
A star system or stellar system is a small number of stars that orbit each other, bound by gravitational attraction.
Starburst galaxy
A starburst galaxy is one undergoing an exceptionally high rate of star formation, as compared to the long-term average rate of star formation in the galaxy, or the star formation rate observed in most other galaxies.
Stars in fiction
Stars outside of the Solar System have been featured as settings in works of fiction since at least the 1600s, though this did not become commonplace until the pulp era of science fiction.
Starspot
Starspots are stellar phenomena, so-named by analogy with sunspots.
Stellar association
A stellar association is a very loose star cluster, looser than both open clusters and globular clusters.
See Star and Stellar association
Stellar atmosphere
The stellar atmosphere is the outer region of the volume of a star, lying above the stellar core, radiation zone and convection zone. Star and stellar atmosphere are stellar astronomy.
See Star and Stellar atmosphere
Stellar classification
In astronomy, stellar classification is the classification of stars based on their spectral characteristics. Star and stellar classification are concepts in astronomy and stellar astronomy.
See Star and Stellar classification
Stellar corona
A corona (coronas or coronae) is the outermost layer of a star's atmosphere. Star and Stellar corona are light sources.
Stellar designations and names
In astronomy, stars have a variety of different stellar designations and names, including catalogue designations, current and historical proper names, and foreign language names. Star and stellar designations and names are stars and stellar astronomy.
See Star and Stellar designations and names
Stellar dynamics
Stellar dynamics is the branch of astrophysics which describes in a statistical way the collective motions of stars subject to their mutual gravity. Star and Stellar dynamics are stars and stellar astronomy.
Stellar evolution
Stellar evolution is the process by which a star changes over the course of its lifetime and how it can lead to the creation of a new star. Star and Stellar evolution are concepts in astronomy and stellar astronomy.
See Star and Stellar evolution
Stellar kinematics
In astronomy, stellar kinematics is the observational study or measurement of the kinematics or motions of stars through space. Star and stellar kinematics are stellar astronomy.
See Star and Stellar kinematics
Stellar mass
Stellar mass is a phrase that is used by astronomers to describe the mass of a star. Star and Stellar mass are stellar astronomy.
Stellar mass loss
Stellar mass loss is a phenomenon observed in stars by which stars lose some mass over their lives. Mass loss can be caused by triggering events that cause the sudden ejection of a large portion of the star's mass.
See Star and Stellar mass loss
Stellar nucleosynthesis
In astrophysics, stellar nucleosynthesis is the creation of chemical elements by nuclear fusion reactions within stars. Star and stellar nucleosynthesis are concepts in astronomy and stellar astronomy.
See Star and Stellar nucleosynthesis
Stellar population
In 1944, Walter Baade categorized groups of stars within the Milky Way into stellar populations. Star and stellar population are stellar astronomy.
See Star and Stellar population
Stellar wind
A stellar wind is a flow of gas ejected from the upper atmosphere of a star. Star and stellar wind are stellar astronomy.
Students for the Exploration and Development of Space
Students for the Exploration and Development of Space (SEDS) is a non-profit international student organization whose purpose is to drive space advocacy of space exploration and development through educational and engineering projects.
See Star and Students for the Exploration and Development of Space
Sun
The Sun is the star at the center of the Solar System. Star and Sun are light sources.
See Star and Sun
Sunspot
Sunspots are temporary spots on the Sun's surface that are darker than the surrounding area.
See Star and Sunspot
Supergiant
Supergiants are among the most massive and most luminous stars.
Supernova
A supernova (supernovae or supernovas) is a powerful and luminous explosion of a star. Star and supernova are concepts in astronomy and light sources.
Supernova impostor
Supernova impostors are stellar explosions that appear at first to be a supernova but do not destroy their progenitor stars.
See Star and Supernova impostor
Supernova remnant
A supernova remnant (SNR) is the structure resulting from the explosion of a star in a supernova.
See Star and Supernova remnant
Surface gravity
The surface gravity, g, of an astronomical object is the gravitational acceleration experienced at its surface at the equator, including the effects of rotation.
T Tauri star
T Tauri stars (TTS) are a class of variable stars that are less than about ten million years old.
The 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.
See Star and The Astrophysical Journal
The Book of Fixed Stars
The Book of Fixed Stars (italic, literally The Book of the Shapes of Stars) is an astronomical text written by Abd al-Rahman al-Sufi (Azophi) around 964.
See Star and The Book of Fixed Stars
The New York Times
The New York Times (NYT) is an American daily newspaper based in New York City.
See Star and The New York Times
Thermal equilibrium
Two physical systems are in thermal equilibrium if there is no net flow of thermal energy between them when they are connected by a path permeable to heat.
See Star and Thermal equilibrium
Timocharis
Timocharis of Alexandria (Τιμόχαρις or Τιμοχάρης, gen. Τιμοχάρους; c. 320–260 BC) was a Greek astronomer and philosopher.
Triple-alpha process
The triple-alpha process is a set of nuclear fusion reactions by which three helium-4 nuclei (alpha particles) are transformed into carbon.
See Star and Triple-alpha process
Twinkling
Twinkling, also called scintillation, is a generic term for variations in apparent brightness, colour, or position of a distant luminous object viewed through a medium.
Tycho Brahe
Tycho Brahe (born Tyge Ottesen Brahe,; 14 December 154624 October 1601), generally called Tycho for short, was a Danish astronomer of the Renaissance, known for his comprehensive and unprecedentedly accurate astronomical observations.
Type Ia supernova
A Type Ia supernova (read: "type one-A") is a type of supernova that occurs in binary systems (two stars orbiting one another) in which one of the stars is a white dwarf.
See Star and Type Ia supernova
Ultraviolet
Ultraviolet (UV) light is electromagnetic radiation of wavelengths of 10–400 nanometers, shorter than that of visible light, but longer than X-rays.
University of California
The University of California (UC) is a public land-grant research university system in the U.S. state of California.
See Star and University of California
Uranus
Uranus is the seventh planet from the Sun.
See Star and Uranus
Vacuum chamber
A vacuum chamber is a rigid enclosure from which air and other gases are removed by a vacuum pump.
Variable star
A variable star is a star whose brightness as seen from Earth (its apparent magnitude) changes with time. Star and variable star are concepts in astronomy.
Vega
Vega is the brightest star in the northern constellation of Lyra.
See Star and Vega
Venus
Venus is the second planet from the Sun.
See Star and Venus
Virgo Cluster
The Virgo Cluster is a large cluster of galaxies whose center is 53.8 ± 0.3 Mly (16.5 ± 0.1 Mpc) away in the constellation Virgo.
Wavelength
In physics and mathematics, wavelength or spatial period of a wave or periodic function is the distance over which the wave's shape repeats.
Westerhout 40
Westerhout 40 or W40 (also designated Sharpless 64, Sh2-64, or RCW 174) is a star-forming region in the Milky Way located in the constellation Serpens.
White dwarf
A white dwarf is a stellar core remnant composed mostly of electron-degenerate matter.
William Herschel
Frederick William Herschel (Friedrich Wilhelm Herschel; 15 November 1738 – 25 August 1822) was a German-British astronomer and composer.
Wolf–Rayet star
Wolf–Rayet stars, often abbreviated as WR stars, are a rare heterogeneous set of stars with unusual spectra showing prominent broad emission lines of ionised helium and highly ionised nitrogen or carbon.
X-ray
X-rays (or rarely, X-radiation) are a form of high-energy electromagnetic radiation.
See Star and X-ray
X-ray burster
X-ray bursters are one class of X-ray binary stars exhibiting X-ray bursts, periodic and rapid increases in luminosity (typically a factor of 10 or greater) that peak in the X-ray region of the electromagnetic spectrum.
Zeta Ophiuchi
Zeta Ophiuchi (ζ Oph, ζ Ophiuchi) is a single star located in the constellation of Ophiuchus.
Zij
A zij (zīj) is an Islamic astronomical book that tabulates parameters used for astronomical calculations of the positions of the sun, moon, stars, and planets.
See Star and Zij
14 Herculis
14 Herculis or 14 Her is a K-type main-sequence star away in the constellation Hercules.
2MASS J0523−1403
2MASS J0523−1403 is a very-low-mass red dwarf or high-mass brown dwarf about 40 light-years from Earth in the southern constellation of Lepus, with a very faint visual magnitude of 21.05 and a low effective temperature of 2074 K. It is visible primarily in large telescopes sensitive to infrared light.
61 Cygni
61 Cygni is a binary star system in the constellation Cygnus, consisting of a pair of K-type dwarf stars that orbit each other in a period of about 659 years.
See also
Stars
- Calibrator star
- HD 30856
- Habitability of F-type main-sequence star systems
- Habitability of yellow dwarf systems
- Hypothetical stars
- Lists of stars
- NGC 308
- Star
- Star clusters
- Star lore
- Star systems
- Star types
- Stellar designations and names
- Stellar dynamics
- Substellar object
References
Also known as Intermediate Stars, Intermediate mass star, Intermediate mass stars, Intermediate star, Intermediate-mass star, Massive star, Star (astronomy), Star fission, Stars, Stellar diameter, Stellar radius, Stellum.
, Blue dwarf (red-dwarf stage), Blue straggler, Blue supergiant, Bok globule, Brightness, British Library, Brocchi's Cluster, Brown dwarf, Business, Cambridge University Press, Canopus, Carbon, Carbon-12, Carbon-burning process, Cataclysmic variable star, Catalysis, Cecilia Payne-Gaposchkin, Celestial navigation, Celestial sphere, Celestial spheres, Centaurus (journal), Centre de données astronomiques de Strasbourg, Centre for Astrophysics and Supercomputing, Cepheid variable, Chemical element, Chemically peculiar star, Chinese astronomy, Chromium, Chromosphere, Civilization, CNO cycle, Color index, Common envelope, Compact object, Concentration, Conjunction (astronomy), Constellation, Contact binary, Convection, Convection zone, Coronal loop, Cosmic distance ladder, Cosmic dust, Cosmology in the Muslim world, Cosmos Redshift 7, Crab Nebula, Degenerate matter, Democritus, Density, Deuterium, Divination, Doppler effect, Dredge-up, Dynamo theory, Ecliptic, Edmond Halley, Edward Charles Pickering, Effective temperature, Egyptian astronomy, Electromagnetic radiation, Electromagnetic spectrum, Electron capture, Electronvolt, Energy flux, Epicurus, Epsilon Indi, Equatorial bulge, Esther, Eta Carinae, European Space Agency, Exoplanet, Extinction (astronomy), Fairfield University, Fakhr al-Din al-Razi, First-magnitude star, Fixed stars, Flamsteed designation, Flare star, Frequency, Friedrich Georg Wilhelm von Struve, Friedrich Wilhelm Bessel, Fusor (astronomy), G-type main-sequence star, Galactic Center, Galactic disc, Galaxy, Galaxy cluster, Gamma ray, Gas giant, Gaussian units, Geminiano Montanari, Giant star, Giordano Bruno, Gliese 65, Globular cluster, Glossary of astronomy, Gradient, Gravitational collapse, Gravitational constant, Gravitational lens, Gravitational microlensing, Greek language, Greek mythology, Gregorian calendar, H II region, Hayashi track, HD 140283, Heliosphere, Helium, Helium flash, Helium-3, Helium-4, Henyey track, Herbig Ae/Be star, Herbig–Haro object, Hertzsprung–Russell diagram, Hipparchus, Horizontal branch, Human eye, Hydrogen, Hydrogen line, Hydrostatic equilibrium, Hypergiant, IAU Working Group on Star Names, Inanna, Infrared, Interacting galaxy, Interferometry, International Astronomical Union, International System of Units, Interstellar medium, Inverse beta decay, Ion, Isaac Newton, Isis (journal), Islamic calendar, Isotopes of beryllium, Isotopes of hydrogen, Jeans instability, Johann Bayer, John Flamsteed, John Herschel, Joseph von Fraunhofer, Jupiter, Karl Schwarzschild, Kassites, Kelvin, Large Magellanic Cloud, Latin, Latitude, Library of Congress, Light-year, Limb darkening, List of Arabic star names, List of most luminous stars, List of most massive stars, List of nearest stars, List of proper names of stars, Lithium, Local Group, Logarithmic scale, Luminosity, Luminous blue variable, Lunar eclipse, MACS J1149 Lensed Star 1, Magnetic field, Main sequence, Main sequence turnoff, Mars, Mass, Mass–energy equivalence, Maunder Minimum, Mercury (planet), Mesopotamia, Messier 100, Messier 87, Metallicity, Milky Way, Minute and second of arc, Mira variable, Mizar, Molecular cloud, Monthly Notices of the Royal Astronomical Society, Moon, Mount Wilson Observatory, Mu Leonis, Myth, National and Kapodistrian University of Athens, Nature (journal), Nebula, Neon, Neon-burning process, Neptune, Neutron star, New York City Department of Consumer and Worker Protection, NGC 6397, Night sky, Nocturnal (instrument), Nova, Nth root, Nuclear fusion, O-type star, Observable universe, Observatory, Occultation, Omicron Velorum, Opacity, Orbital elements, Orion (constellation), Orion Nebula, Orion's Belt, Outer space, Outline of astronomy, Oxygen, Oxygen-burning process, Parallax, Particle radiation, Perseus molecular cloud, Persians, Photoelectric effect, Photographic magnitude, Photometer, Photon, Photosphere, Planck (spacecraft), Planet, Planetary nebula, Planetary system, Plasma (physics), Polymath, Positron, Power (physics), Pre-main-sequence star, Pressure gradient, Procyon, Proper motion, Proper noun, Proto-Indo-European language, Proton, Proton–proton chain, Protoplanetary disk, Protostar, Proxima Centauri, Ptolemy, Pulsar, QCD matter, Quantum mechanics, R Doradus, R136, Radial velocity, Radiant energy, Radiation, Radiation pressure, Radiation zone, Radio frequency, Radius, Rare-earth element, Red clump, Red dwarf, Red giant, Red supergiant, Red-giant branch, Refraction, Regulation, Richard Bentley, Rigel, Right ascension, Roche lobe, Roman mythology, Rotation, Sand, Saturn, Second, Self-gravitation, Semi-major and semi-minor axes, Sherburne Wesley Burnham, Shock wave, Sidereal time, Silicon, Silicon-burning process, Sirius, SN 1006, SN 1054, SN 185, Solar calendar, Solar eclipse, Solar flare, Solar luminosity, Solar mass, Solar radius, Solar spicule, Solar wind, Space, Space Shuttle, Space.com, Spectral line, Spectroscopy, Spheroid, Spiral galaxy, Stanford Encyclopedia of Philosophy, Star catalogue, Star chart, Star cluster, Star count, Star formation, Star system, Starburst galaxy, Stars in fiction, Starspot, Stellar association, Stellar atmosphere, Stellar classification, Stellar corona, Stellar designations and names, Stellar dynamics, Stellar evolution, Stellar kinematics, Stellar mass, Stellar mass loss, Stellar nucleosynthesis, Stellar population, Stellar wind, Students for the Exploration and Development of Space, Sun, Sunspot, Supergiant, Supernova, Supernova impostor, Supernova remnant, Surface gravity, T Tauri star, The Astrophysical Journal, The Book of Fixed Stars, The New York Times, Thermal equilibrium, Timocharis, Triple-alpha process, Twinkling, Tycho Brahe, Type Ia supernova, Ultraviolet, University of California, Uranus, Vacuum chamber, Variable star, Vega, Venus, Virgo Cluster, Wavelength, Westerhout 40, White dwarf, William Herschel, Wolf–Rayet star, X-ray, X-ray burster, Zeta Ophiuchi, Zij, 14 Herculis, 2MASS J0523−1403, 61 Cygni.