74 relations: Absolute magnitude, Alpha Cygni variable, Alpha Herculis, Antares, Antonia Maury, Asymptotic giant branch, B(e) star, Betelgeuse, Blue supergiant star, Bolometric correction, Chemical element, Classical Cepheid variable, CNO cycle, Constellation, Cygnus (constellation), Delta Cephei, Deneb, Dover Publications, Ejnar Hertzsprung, Elliptical galaxy, Forbidden mechanism, Globular cluster, HD 93129, Helium, Hertzsprung–Russell diagram, Hydrogen, Hypergiant, Instability strip, Irregular galaxy, Irregular variable, List of stars with resolved images, Luminosity, Luminous blue variable, Maser, Microturbulence, Mira variable, Mu Cephei, O-type main-sequence star, Open cluster, Orion (constellation), P Cygni, Planetary nebula, PV Telescopii variable, Quasar, R Coronae Borealis variable, Radius, Red supergiant star, Rho Cassiopeiae, Rigel, RV Tauri, ..., RV Tauri variable, S-process, Semiregular variable star, SN 1987A, Solar radius, Spectral line, Spiral galaxy, Star, Stefan–Boltzmann law, Stellar classification, Stellar population, Sun, Supernova, Surface gravity, Universe, VX Sagittarii, W Mensae, W Virginis, W Virginis variable, White dwarf, Wolf–Rayet star, Yellow hypergiant, Yellow supergiant star, 14 Persei. Expand index (24 more) »
Absolute magnitude is a measure of the luminosity of a celestial object, on a logarithmic astronomical magnitude scale.
Alpha Cygni variables are variable stars which exhibit non-radial pulsations, meaning that some portions of the stellar surface are contracting at the same time others parts expand.
Antares, also designated Alpha Scorpii (α Scorpii, abbreviated Alpha Sco, α Sco), is on average the fifteenth-brightest star in the night sky, and the brightest star in the constellation of Scorpius.
Antonia Maury (March 21, 1866 – January 8, 1952) was an American astronomer who published an important early catalog of stellar spectra.
The asymptotic giant branch (AGB) is a region of the Hertzsprung–Russell diagram populated by evolved cool luminous stars.
A B star, frequently called a B-type star, is a B-type star with distinctive forbidden neutral or low ionisation emission lines in its spectrum.
Betelgeuse, also designated Alpha Orionis (α Orionis, abbreviated Alpha Ori, α Ori), is the ninth-brightest star in the night sky and second-brightest in the constellation of Orion.
Blue supergiant stars are hot luminous stars, referred to scientifically as OB supergiants.
In astronomy, the bolometric correction is the correction made to the absolute magnitude of an object in order to convert its visible magnitude to its bolometric magnitude.
A chemical element is a species of atoms having the same number of protons in their atomic nuclei (that is, the same atomic number, or Z).
Classical Cepheids (also known as Population I Cepheids, Type I Cepheids, or Delta Cephei variables) are a type of Cepheid variable star.
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.
A constellation is a group of stars that are considered to form imaginary outlines or meaningful patterns on the celestial sphere, typically representing animals, mythological people or gods, mythological creatures, or manufactured devices.
Cygnus is a northern constellation lying on the plane of the Milky Way, deriving its name from the Latinized Greek word for swan.
Delta Cephei (δ Cep, δ Cephei) is the Bayer designation for a quadruple star system located approximately 887 light-years away in the northern circumpolar constellation of Cepheus, the King.
Deneb, also designated α Cygni (Latinised alpha Cygni, abbreviated Alpha Cyg, α Cyg), is the brightest star in the constellation of Cygnus.
Dover Publications, also known as Dover Books, is an American book publisher founded in 1941 by Hayward Cirker and his wife, Blanche.
Ejnar Hertzsprung (8 October 1873 – 21 October 1967) was a Danish chemist and astronomer born in Copenhagen.
An elliptical galaxy is a type of galaxy having an approximately ellipsoidal shape and a smooth, nearly featureless image.
In spectroscopy, a forbidden mechanism (forbidden transition or forbidden line) is a spectral line associated with absorption or emission of light by atomic nuclei, atoms, or molecules which undergo a transition that is not allowed by a particular selection rule but is allowed if the approximation associated with that rule is not made.
A globular cluster is a spherical collection of stars that orbits a galactic core as a satellite.
HD 93129 is a triple star system in the Carina Nebula, with all three components being hot O class stars amongst the most luminous stars in the Milky Way.
Helium (from lit) is a chemical element with symbol He and atomic number 2.
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.
A hypergiant (luminosity class 0 or Ia+) is among the very rare kinds of stars that typically show tremendous luminosities and very high rates of mass loss by stellar winds.
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.
An irregular galaxy is a galaxy that does not have a distinct regular shape, unlike a spiral or an elliptical galaxy.
An irregular variable is a type of variable star in which variations in brightness show no regular periodicity.
The following is a list of stars whose images have been resolved beyond a point source.
In astronomy, luminosity is the total amount of energy emitted per unit of time by a star, galaxy, or other astronomical object.
Luminous blue variables (LBVs) are massive evolved stars that show unpredictable and sometimes dramatic variations in both their spectra and brightness.
A maser (an acronym for "microwave amplification by stimulated emission of radiation") is a device that produces coherent electromagnetic waves through amplification by stimulated emission.
Microturbulence is a form of turbulence that varies over small distance scales.
Mira variables ("Mira", Latin, adj. - feminine form of adjective "wonderful"), named for the prototype star Mira, are a class of pulsating variable 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.
Mu Cephei (μ Cep, μ Cephei), also known as Herschel's Garnet Star, is a red supergiant star in the constellation Cepheus.
An O-type main-sequence star (O V) is a main-sequence (core hydrogen-burning) star of spectral type O and luminosity class V. These stars have between 15 and 90 times the mass of the Sun and surface temperatures between 30,000 and 50,000 K. They are between 40,000 and 1,000,000 times as luminous as the Sun.
An open cluster is a group of up to a few thousand stars that were formed from the same giant molecular cloud and have roughly the same age.
Orion is a prominent constellation located on the celestial equator and visible throughout the world.
P Cygni (34 Cyg) is a variable star in the constellation Cygnus.
A planetary nebula, abbreviated as PN or plural PNe, is a type of emission nebula consisting of an expanding, glowing shell of ionized gas ejected from red giant stars late in their lives.
PV Telescopii variable is a type of variable star that is established in the General Catalogue of Variable Stars with the acronym PVTEL.
A quasar (also known as a QSO or quasi-stellar object) is an extremely luminous active galactic nucleus (AGN).
An R Coronae Borealis variable (abbreviated RCB, R CrB) is an eruptive variable star that varies in luminosity in two modes, one low amplitude pulsation (a few tenths of a magnitude), and one irregular, unpredictably-sudden fading by 1 to 9 magnitudes.
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.
Red supergiants are stars with a supergiant luminosity class (Yerkes class I) of spectral type K or M. They are the largest stars in the universe in terms of volume, although they are not the most massive or luminous.
Rho Cassiopeiae (ρ Cas, ρ Cassiopeiae) is a yellow hypergiant star in the constellation Cassiopeia.
Rigel, also designated Beta Orionis (β Orionis, abbreviated Beta Ori, β Ori), is generally the seventh-brightest star in the night sky and the brightest star in the constellation of Orion—though periodically it is outshone within the constellation by the variable Betelgeuse.
RV Tauri (RV Tau) is a star in the constellation Taurus.
RV Tauri variables are luminous variable stars that have distinctive light variations with alternating deep and shallow minima.
The slow neutron-capture process or s-process is a series of reactions in nuclear astrophysics that occur in stars, particularly AGB stars.
Semiregular variable stars are giants or supergiants of intermediate and late spectral type showing considerable periodicity in their light changes, accompanied or sometimes interrupted by various irregularities.
SN 1987A was a peculiar type II supernova in the Large Magellanic Cloud, a dwarf galaxy satellite of the Milky Way.
Solar radius is a unit of distance used to express the size of stars in astronomy.
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.
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.
A star is type of astronomical object consisting of a luminous spheroid of plasma held together by its own gravity.
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.
During 1944, Walter Baade categorized groups of stars within the Milky Way into bluer stars associated with the spiral arms and the general position of yellow stars near the central galactic bulge or within globular star clusters.
The Sun is the star at the center of the Solar System.
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.
The surface gravity, g, of an astronomical or other object is the gravitational acceleration experienced at its surface.
The Universe is all of space and time and their contents, including planets, stars, galaxies, and all other forms of matter and energy.
VX Sagittarii is a red supergiant or red hypergiant located more than 1.5 kiloparsec away from the Sun in the constellation of Sagittarius.
W Mensae (W Men) is an unusual yellow supergiant star in the Large Magellanic Cloud in the southern constellation Mensa.
W Virginis is the prototype W Virginis variable, a subclass of the Cepheid variable stars.
W Virginis variables are a subclass of Type II Cepheids which exhibit pulsation periods between 10–20 days,Wallerstein, G.,, Publications of the Astronomical Society of the Pacific, 114 p.689–699 (2002) and are of spectral class F6 – K2.
A white dwarf, also called a degenerate dwarf, is a stellar core remnant composed mostly of electron-degenerate matter.
Wolf–Rayet stars, often abbreviated as WR stars, are a rare heterogeneous set of stars with unusual spectra showing prominent broad emission lines of highly ionised helium and nitrogen or carbon.
A yellow hypergiant is a massive star with an extended atmosphere, a spectral class from A to K, and an initial mass of about 20–60 solar masses but having lost as much as half that mass.
A yellow supergiant star is a star, generally of spectral type F or G, having a supergiant luminosity class (e.g. Ia or Ib).
14 Persei is a star in the constellation Perseus.