127 relations: Absolute magnitude, Alpha Coronae Borealis, Alpha Mensae, American Institute of Physics, Annie Jump Cannon, Apparent magnitude, Astronomy, Bengt Strömgren, Beta Cephei variable, Beta Comae Berenices, Beta Pictoris, Binary star, Black body, Black hole, Bristol, Brown dwarf, Cambridge, Carbon, Cepheid variable, Chicago, CNO cycle, Color index, Convection, Convection zone, Curve, Delta Scuti variable, Dwarf star, Earth, Edward Charles Pickering, Effective temperature, Ejnar Hertzsprung, Electron degeneracy pressure, Electron scattering, Erg, Eta Arietis, Exothermic process, Extinction (astronomy), EZ Aquarii, G-type main-sequence star, Gamma Virginis, Gram, Gravitational collapse, Harvard College Observatory, HD 32450, Heinrich Vogt (astronomer), Helium, Henry Norris Russell, Hertzsprung–Russell diagram, Hydrogen, Hydrostatic equilibrium, ..., Initial mass function, Instability strip, Institute of Physics, Interstellar medium, Jeans instability, Jupiter, K-type main-sequence star, Kelvin, Luminosity, MACS J1149 Lensed Star 1, Mass, Mass–luminosity relation, Metallicity, Mnemonic, Molecular cloud, Monthly Notices of the Royal Astronomical Society, Nature (journal), New York (state), New York City, Nitrogen, Nuclear fusion, Opacity (optics), Order of approximation, Order of magnitude, Oxygen, Parallax, Phi Orionis, Philip Childs Keenan, Photosphere, Pi Andromedae, Plasma (physics), Potsdam, Power law, Pre-main-sequence star, Princeton University, Princeton University Press, Proton–proton chain reaction, Protostar, Quantum mechanics, Radiation, Radiation zone, Radius, Red dwarf, Red giant, Sirius, Solar luminosity, Solar mass, Space.com, Spectral line, Star, Star cluster, Stefan–Boltzmann constant, Stefan–Boltzmann law, Stellar classification, Stellar evolution, Stellar magnetic field, Stellar rotation, Subdwarf, Sun, Supergiant star, Supernova, Thermal energy, Theta1 Orionis C, Triple-alpha process, Turnoff point, Type Ib and Ic supernovae, Type II supernova, University of Cambridge, University of Chicago, University of Oxford, Variable star, VB 10, Vogt–Russell theorem, White dwarf, William Wilson Morgan, 61 Cygni, 70 Ophiuchi. Expand index (77 more) » « Shrink index
Absolute magnitude is a measure of the luminosity of a celestial object, on a logarithmic astronomical magnitude scale.
Alpha Coronae Borealis (α Coronae Borealis, abbreviated Alpha CrB, α CrB), also named Alphecca, is a binary star in the constellation of Corona Borealis.
α Mensae (Latinised as Alpha Mensae, abbreviated to α Men or Alpha Men) is the brightest star in the constellation Mensa.
The American Institute of Physics (AIP) promotes science, the profession of physics, publishes physics journals, and produces publications for scientific and engineering societies.
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.
The apparent magnitude of a celestial object is a number that is a measure of its brightness as seen by an observer on Earth.
Astronomy (from ἀστρονομία) is a natural science that studies celestial objects and phenomena.
Bengt Georg Daniel Strömgren (21 January 1908 – 4 July 1987) was a Danish astronomer and astrophysicist.
Beta Cephei variables, also known as Beta Canis Majoris stars, are variable stars that exhibit small rapid variations in their brightness due to pulsations of the stars' surfaces, thought due to the unusual properties of iron at temperatures of 200,000 K in their interiors.
Beta Comae Berenices (β Comae Berenices, β Com) is a main sequence dwarf star in the northern constellation of Coma Berenices.
Beta Pictoris (β Pic, β Pictoris) is the second brightest star in the constellation Pictor.
A binary star is a star system consisting of two stars orbiting around their common barycenter.
A black body is an idealized physical body that absorbs all incident electromagnetic radiation, regardless of frequency or angle of incidence.
A black hole is a region of spacetime exhibiting such strong gravitational effects that nothing—not even particles and electromagnetic radiation such as light—can escape from inside it.
Bristol is a city and county in South West England with a population of 456,000.
Brown dwarfs are substellar objects that occupy the mass range between the heaviest gas giant planets and the lightest stars, having masses between approximately 13 to 75–80 times that of Jupiter, or approximately to about.
Cambridge is a university city and the county town of Cambridgeshire, England, on the River Cam approximately north of London.
Carbon (from carbo "coal") is a chemical element with symbol C and atomic number 6.
A Cepheid variable is a type of star that pulsates radially, varying in both diameter and temperature and producing changes in brightness with a well-defined stable period and amplitude.
Chicago, officially the City of Chicago, is the third most populous city in the United States, after New York City and Los Angeles.
The CNO cycle (for carbon–nitrogen–oxygen) 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.
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.
Convection is the heat transfer due to bulk movement of molecules within fluids such as gases and liquids, including molten rock (rheid).
A convection zone, convective zone or convective region of a star is a layer which is unstable to convection.
In mathematics, a curve (also called a curved line in older texts) is, generally speaking, an object similar to a line but that need not be straight.
A Delta Scuti variable (sometimes termed dwarf cepheid) is a variable star which exhibits variations in its luminosity due to both radial and non-radial pulsations of the star's surface.
A dwarf star is a star of relatively small size and low luminosity.
Earth is the third planet from the Sun and the only astronomical object known to harbor life.
Prof Edward Charles Pickering FRS(For) HFRSE (July 19, 1846 – February 3, 1919) was an American astronomer and physicist and the older brother to William Henry Pickering.
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.
Ejnar Hertzsprung (8 October 1873 – 21 October 1967) was a Danish chemist and astronomer born in Copenhagen.
Electron degeneracy pressure is a particular manifestation of the more general phenomenon of quantum degeneracy pressure.
Electron scattering occurs when electrons are deviated from their original trajectory.
The erg is a unit of energy and work equal to 10−7 joules.
Eta Arietis (η Ari, η Arietis) is the Bayer designation for a star in the northern constellation of Aries.
In thermodynamics, the term exothermic process (exo-: "outside") describes a process or reaction that releases energy from the system to its surroundings, usually in the form of heat, but also in a form of light (e.g. a spark, flame, or flash), electricity (e.g. a battery), or sound (e.g. explosion heard when burning hydrogen).
In astronomy, extinction is the absorption and scattering of electromagnetic radiation by dust and gas between an emitting astronomical object and the observer.
EZ Aquarii is a triple star system approximately from the Sun in the constellation Aquarius.
A G-type main-sequence star (Spectral type: G-V), often (and imprecisely) called a yellow dwarf, or G dwarf star, is a main-sequence star (luminosity class V) of spectral type G. Such a star has about 0.84 to 1.15 solar masses and surface temperature of between 5,300 and 6,000 K., G. M. H. J. Habets and J. R. W. Heintze, Astronomy and Astrophysics Supplement 46 (November 1981), pp.
Gamma Virginis (γ Virginis, abbreviated Gamma Vir, γ Vir), also named Porrima, is a binary star system in the constellation of Virgo.
The gram (alternative spelling: gramme; SI unit symbol: g) (Latin gramma, from Greek γράμμα, grámma) is a metric system unit of mass.
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.
The Harvard College Observatory (HCO) is an institution managing a complex of buildings and multiple instruments used for astronomical research by the Harvard University Department of Astronomy.
HD 32450, also known as Gliese 185 is a binary star in the constellation Lepus.
Heinrich Vogt (October 5, 1890 – January 23, 1968) was a German astronomer.
Helium (from lit) is a chemical element with symbol He and atomic number 2.
Prof Henry Norris Russell FRS(For) HFRSE FRAS (October 25, 1877 – February 18, 1957) was an American astronomer who, along with Ejnar Hertzsprung, developed the Hertzsprung–Russell diagram (1910).
The Hertzsprung–Russell diagram, abbreviated H–R diagram, HR diagram or HRD, is a scatter plot of stars showing the relationship between the stars' absolute magnitudes or luminosities versus their stellar classifications or effective temperatures.
Hydrogen is a chemical element with symbol H and atomic number 1.
In fluid mechanics, a fluid is said to be in hydrostatic equilibrium or hydrostatic balance when it is at rest, or when the flow velocity at each point is constant over time.
In astronomy, the initial mass function (IMF) is an empirical function that describes the initial distribution of masses for a population of stars.
The unqualified term instability strip usually refers to a region of the Hertzsprung–Russell diagram largely occupied by several related classes of pulsating variable stars: Delta Scuti variables, SX Phoenicis variables, and rapidly oscillating Ap stars (roAps) near the main sequence; RR Lyrae variables where it intersects the horizontal branch; and the Cepheid variables where it crosses the supergiants.
The Institute of Physics (IOP) is a scientific charity that works to advance physics education, research and application.
In astronomy, the interstellar medium (ISM) is the matter and radiation that exists in the space between the star systems in a galaxy.
In stellar physics, the Jeans instability causes the collapse of interstellar gas clouds and subsequent star formation.
Jupiter is the fifth planet from the Sun and the largest in the Solar System.
A K-type main-sequence star (K V), also referred to as an orange dwarf or K dwarf, is a main-sequence (hydrogen-burning) star of spectral type K and luminosity class V. These stars are intermediate in size between red M-type main-sequence stars ("red dwarfs") and yellow G-type main-sequence stars.
The Kelvin scale is an absolute thermodynamic temperature scale using as its null point absolute zero, the temperature at which all thermal motion ceases in the classical description of thermodynamics.
In astronomy, luminosity is the total amount of energy emitted per unit of time by a star, galaxy, or other astronomical object.
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 observed through a gravitational lens.
Mass is both a property of a physical body and a measure of its resistance to acceleration (a change in its state of motion) when a net force is applied.
In astrophysics, the mass–luminosity relation is an equation giving the relationship between a star's mass and its luminosity, first noted by Jakob Karl Ernst Halm.
In astronomy, metallicity is used to describe the abundance of elements present in an object that are heavier than hydrogen or helium.
A mnemonic (the first "m" is silent) device, or memory device, is any learning technique that aids information retention or retrieval (remembering) in the human memory.
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 the formation of molecules, most commonly molecular hydrogen (H2).
Monthly Notices of the Royal Astronomical Society (MNRAS) is a peer-reviewed scientific journal covering research in astronomy and astrophysics.
Nature is a British multidisciplinary scientific journal, first published on 4 November 1869.
New York is a state in the northeastern United States.
The City of New York, often called New York City (NYC) or simply New York, is the most populous city in the United States.
Nitrogen is a chemical element with symbol N and atomic number 7.
In nuclear physics, nuclear fusion is a reaction in which two or more atomic nuclei come close enough to form one or more different atomic nuclei and subatomic particles (neutrons or protons).
Opacity is the measure of impenetrability to electromagnetic or other kinds of radiation, especially visible light.
In science, engineering, and other quantitative disciplines, orders of approximation refer to formal or informal terms for how precise an approximation is, and to indicate progressively more refined approximations: in increasing order of precision, a zeroth-order approximation, a first-order approximation, a second-order approximation, and so forth.
An order of magnitude is an approximate measure of the number of digits that a number has in the commonly-used base-ten number system.
Oxygen is a chemical element with symbol O and atomic number 8.
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 semi-angle of inclination between those two lines.
The Bayer designation Phi Orionis (φ Ori, φ Orionis) is shared by two star systems in the constellation Orion.
Philip Childs Keenan (March 31, 1908 – April 20, 2000) was an American astronomer.
The photosphere is a star's outer shell from which light is radiated.
Pi Andromedae (Pi And, π Andromedae, π And) is the Bayer designation for a binary star system in the northern constellation of Andromeda.
Plasma (Henry George Liddell, Robert Scott, A Greek English Lexicon, on Perseus) is one of the four fundamental states of matter, and was first described by chemist Irving Langmuir in the 1920s.
Potsdam is the capital and largest city of the German federal state of Brandenburg.
In statistics, a power law is a functional relationship between two quantities, where a relative change in one quantity results in a proportional relative change in the other quantity, independent of the initial size of those quantities: one quantity varies as a power of another.
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.
Princeton University is a private Ivy League research university in Princeton, New Jersey.
Princeton University Press is an independent publisher with close connections to Princeton University.
The proton–proton chain reaction is one of the two (known) sets of fusion reactions by which stars convert hydrogen to helium.
A protostar is a very young star that is still gathering mass from its parent molecular cloud.
Quantum mechanics (QM; also known as quantum physics, quantum theory, the wave mechanical model, or matrix mechanics), including quantum field theory, is a fundamental theory in physics which describes nature at the smallest scales of energy levels of atoms and subatomic particles.
In physics, radiation is the emission or transmission of energy in the form of waves or particles through space or through a material medium.
A radiation zone, radiative 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.
In classical geometry, a radius 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.
A red dwarf (or M dwarf) is a small and relatively cool star on the main sequence, of M spectral type.
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.
Sirius (a romanization of Greek Σείριος, Seirios,."glowing" or "scorching") is a star system and the brightest star in the Earth's night sky.
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.
The solar mass is a standard unit of mass in astronomy, equal to approximately.
Space.com is a space and astronomy news website.
A spectral line is a dark or bright line in an otherwise uniform and continuous spectrum, resulting from emission or absorption of light in a narrow frequency range, compared with the nearby frequencies.
A star is type of astronomical object consisting of a luminous spheroid of plasma held together by its own gravity.
Star clusters are groups of stars.
The Stefan–Boltzmann constant (also Stefan's constant), a physical constant denoted by the Greek letter ''σ'' (sigma), is the constant of proportionality in the Stefan–Boltzmann law: "the total intensity radiated over all wavelengths increases as the temperature increases", of a black body which is proportional to the fourth power of the thermodynamic temperature.
The Stefan–Boltzmann law describes the power radiated from a black body in terms of its temperature.
In astronomy, stellar classification is the classification of stars based on their spectral characteristics.
Stellar evolution is the process by which a star changes over the course of time.
A stellar magnetic field is a magnetic field generated by the motion of conductive plasma inside a star.
Stellar rotation is the angular motion of a star about its axis.
A subdwarf, sometimes denoted by "sd", is a star with luminosity class VI under the Yerkes spectral classification system.
The Sun is the star at the center of the Solar System.
Supergiants are among the most massive and most luminous stars.
A supernova (plural: supernovae or supernovas, abbreviations: SN and SNe) is a transient astronomical event that occurs during the last stellar evolutionary stages of a star's life, either a massive star or a white dwarf, whose destruction is marked by one final, titanic explosion.
Thermal energy is a term used loosely as a synonym for more rigorously-defined thermodynamic quantities such as the internal energy of a system; heat or sensible heat, which are defined as types of transfer of energy (as is work); or for the characteristic energy of a degree of freedom in a thermal system kT, where T is temperature and k is the Boltzmann constant.
Theta1 Orionis C (θ1 Orionis C) is a member of the Trapezium open cluster that lies within the Orion Nebula.
The triple-alpha process is a set of nuclear fusion reactions by which three helium-4 nuclei (alpha particles) are transformed into carbon.
The turnoff point for a star refers to the point on the Hertzsprung-Russell diagram where it leaves the main sequence after the exhaustion of its main fuel.
Type Ib and Type Ic supernovae are categories of supernovae that are caused by the core collapse of massive stars.
A Type II supernova (plural: supernovae or supernovas) results from the rapid collapse and violent explosion of a massive star.
The University of Cambridge (informally Cambridge University)The corporate title of the university is The Chancellor, Masters, and Scholars of the University of Cambridge.
The University of Chicago (UChicago, U of C, or Chicago) is a private, non-profit research university in Chicago, Illinois.
The University of Oxford (formally The Chancellor Masters and Scholars of the University of Oxford) is a collegiate research university located in Oxford, England.
A variable star is a star whose brightness as seen from Earth (its apparent magnitude) fluctuates.
VB 10 or Van Biesbroeck's star is a very small and very dim red dwarf located in the constellation Aquila.
The Vogt–Russell theorem states that the structure of a star, in hydrostatic and thermal equilibrium with all energy derived from nuclear reactions, is uniquely determined by its mass and the distribution of chemical elements throughout its interior.
A white dwarf, also called a degenerate dwarf, is a stellar core remnant composed mostly of electron-degenerate matter.
William Wilson Morgan (January 3, 1906 – June 21, 1994) was an American astronomer and astrophysicist.
61 Cygni Not to be confused with 16 Cygni, a more distant system containing two G-type stars harboring the gas giant planet 16 Cygni Bb.
70 Ophiuchi is a binary star system located 16.6 light years away from the Earth.
Dwarf (star), Evolutionary track, Main Sequence, Main Sequence Star, Main line star, Main sequence star, Main sequence stars, Main-line star, Main-sequence, Main-sequence star, Main-sequence stars, ZAMS, Zero age main sequence, Zero-age main sequence.