Term Index (B)
- B: photometric filter for blue light
- B field:
- B(e) star:
- Be star: early star with Balmer emission lines
- B-band:
- B-class:
- B-type star (B): type of star with about 10 times the mass of the Sun
- B-E statistics:
- B-mode:
- B-type star (B): type of star with about 10 times the mass of the Sun
- B-V:
- color index: a number that characterizes the color of an object
- B/SN:
- B1875.0:
- B1900.0:
- epoch B1950.0: midnight 1/1/1950 GMT as used as a time reference
- terrestrial time (TT): current measure of time for astronomical observations on Earth
- B1900.0 epoch:
- epoch: time on which to base celestial coordinates
- B1925.0:
- B1950.0:
- epoch B1950.0: midnight 1/1/1950 GMT as used as a time reference
- terrestrial time (TT): current measure of time for astronomical observations on Earth
- B1950.0 epoch:
- epoch: time on which to base celestial coordinates
- B1950.0 equinox:
- J2000.0 equinox: equinox as of the J2000.0 epoch used as a positional reference
- B1957+20:
- Black Widow Pulsar (B1957+20, PSR J1959+2048, PSR B1957+20): binary system consisting of a pulsar and small companion
- B2:
- B3:
- Baade Telescope:
- Baade's Window: region of sky allowing observation into the galactic center
- BAC:
- back end:
- back end instrument: instruments of a telescope that process or combine signals
- background:
- Background Imaging of Cosmic Extragalactic Polarization:
- BICEP2: survey to measure the polarization of the CMB
- backward Fourier transform:
- Fourier transform: systematic method of breaking down functions into periodic components
- backward model:
- forward model: model producing potential observable values from parameters
- Badgerys Creek 101MHz Interferometer:
- Badgerys Creek Interferometer 101MHz Survey (Mills): early 1950s survey of southern-hemisphere radio sources
- baffle:
- Lyot stop: optical element to block unwanted light within instruments
- stray light: unintended light reaching a telescope's sensors
- Balbus-Hawley Instability:
- Balloon-borne Large Aperture Submillimeter Telescope:
- BLAST: balloon-borne 1.8m submillimeter telescope
- Balmer:
- Balmer series: hydrogen lines for electrons settling from n > 2 to n = 2
- Balmer discontinuity:
- Balmer jump: abrupt change in stellar spectrum at end of Balmer series
- Balmer jump: abrupt change in stellar spectrum at end of Balmer series
- Balmer limit:
- Balmer series: hydrogen lines for electrons settling from n > 2 to n = 2
- Balmer jump: abrupt change in stellar spectrum at end of Balmer series
- Balmer-break galaxy (BBG): a galaxy emitting very little shorter than 3646 angstroms
- Be star: early star with Balmer emission lines
- H-alpha (Ha,Hα, H-α): hydrogen line for electrons settling from n = 3 to n = 2
- Balmer's constant:
- Balmer series: hydrogen lines for electrons settling from n > 2 to n = 2
- Balmer-break galaxy (BBG): a galaxy emitting very little shorter than 3646 angstroms
- band:
- B: photometric filter for blue light
- extreme ultraviolet (EUV,XUV): electromagnetic radiation in the range of 10nm-124nm
- extremely low frequency (ELF): electromagnetic radiation, frequency 3Hz to 30Hz
- far infrared (FIR): infrared radiation with wavelengths in the 30-450um range
- G band: band of visible light around 5100 angstroms
- gamma rays: electromagnetic radiation, wavelength 10 picometers and less
- I band: photometric filter for near infrared light
- infrared (IR): electromagnetic radiation, wavelength .74-300 micrometers
- K band: atmospheric window centered around 2.2 microns, or 136 THz
- microwave: electromagnetic radiation, frequency 300MHz to 300GHz
- mid infrared (MIR): infrared radiation with wavelengths in the 7.5um-25um range
- near infrared (NIR,near-IR): electromagnetic radiation in the range of 800-2500 nm
- OIR: a spectral "band name" for both visible light and infrared
- passband: range of electromagnetic wavelengths that a filter allows
- R band: band of visible light around 6500 angstroms
- radio: electromagnetic radiation, frequency 3kHz to 300GHz
- spectral band: set of related, closely-packed spectral lines
- subradio: electromagnetic radiation, frequency below 3kHz
- super low frequency (SLF): electromagnetic radiation, frequency 30Hz to 300Hz
- tremendously low frequency (TLF): electromagnetic radiation, frequency below 3Hz
- U: photometric filter for ultraviolet light
- ultra low frequency (ULF): electromagnetic radiation, frequency 300Hz to 3kHz
- ultra-high-energy gamma rays (UHEGR): energetic gamma rays with more than 100 TeV photon energy
- ultraviolet (UV): electromagnetic radiation, wavelength 10-400 nm
- UVOIR: a spectral "band name" covering UV, visible light, and IR
- V: photometric filter for visible light
- very low frequency (VLF): electromagnetic radiation, frequency 3kHz to 30kHz
- very-high-energy gamma rays (VHEGR): energetic gamma rays with 100 GeV to 100 TeV photon energy
- visible light: electromagnetic radiation, wavelength 390-750 nm
- X-ray: electromagnetic radiation, wavelength .01 to 10 nanometers
- XEUV: electromagnetic radiation in the range of .15nm-400nm
- zone: apparent "horizontal" band in an atmosphere
- band absorption:
- band shifting: effect of redshift on photometry
- bandpass filter:
- filter: optical device to filter out part of the EMR spectrum
- bandwidth: number of hertz between minimum and maximum frequencies
- BAO:
- BAO standard ruler:
- bar: central feature of some spiral galaxies
- barium:
- Am star: A-type star with metallic lines
- barium star:
- Barnard:
- Barnard Catalog (Barnard,B): 1919 catalog of dark nebulae
- Barnard object:
- Barnard's Star: nearby red dwarf
- baroclinic atmosphere:
- baroclinicity: measure of misalignment of fluid density and pressure
- baroclinic instability:
- baroclinicity: measure of misalignment of fluid density and pressure
- baroclinicity: measure of misalignment of fluid density and pressure
- barotropic atmosphere:
- baroclinicity: measure of misalignment of fluid density and pressure
- barred:
- bar: central feature of some spiral galaxies
- spiral galaxy: flat galaxy with spiraling arms
- barred galaxy:
- barred spiral galaxy:
- bar: central feature of some spiral galaxies
- barrier:
- barrier penetration:
- barriers:
- barycenter: center of mass of two orbiting bodies
- barycentric:
- barycentric coordinate time:
- time standard: method of designating points in time and quantifying time periods
- barycentric coordinates:
- barycentric dynamical time:
- time standard: method of designating points in time and quantifying time periods
- barycentric Julian day BJD:
- Julian date (JD): time in days since noon UT November 24 4714 BC Gregorian
- baryogenesis:
- antimatter: similar to normal matter but with opposite electrical charge
- baryon: protons, neutrons, and other three-quark particles
- baryon acoustic oscillations (BAO): density fluctuations stemming from acoustic waves in the early universe
- baryon density:
- Lambda-CDM model (ΛCDM,LCDM): Big-Bang cosmological model with a cosmological constant and cold dark matter
- Baryon Oscillation Spectroscopic Survey (BOSS): survey of spatial distribution of luminous red galaxies and quasars
- baryonic gas fraction:
- gas fraction: fraction of a galaxy or cluster consisting of gas
- baryonic mass density:
- baryonic matter:
- baryon: protons, neutrons, and other three-quark particles
- baryonic Tully-Fisher relation:
- Bas:
- basalt: an igneous rock type that shows rapid cooling
- Basel:
- Basel Astronomical Institute:
- Basel Open Cluster Catalog (Basel): list of open clusters
- baseline: distance between dishes of an interferometer
- parallax: angle due to different lines of sight
- basicity:
- acidity (pH): measure of the activity of hydrogen ions in a solution
- basis function: one of a set of functions used to approximate a function of interest
- BAT:
- Swift: satellite for studying gamma-ray bursts
- bathymetry: study and measurement of sea depths
- BATSE:
- Bayer designation: star designation system dating from 1600s
- Bayes' law:
- Bayes' rule:
- Bayes' theorem:
- Bayesian probabilities:
- Bayesian statistics: statistics method assigning probability to your belief
- BB:
- BBFS:
- HEAO-2: 1978 X-ray observatory space mission
- BBG:
- BBH:
- BBN:
- BCG:
- Bcool: project studying stellar magnetism
- BCS:
- Yohkoh: 1990s Japanese solar observatory spacecraft
- BD:
- BD+36 2147:
- BDF: field used in search for distant galaxies
- BDS:
- Be:
- Be star: early star with Balmer emission lines
- Beagle 2:
- BearCLAW:
- Becker, White, and Edwards Catalog (BWE): 1990s radio catalog from a 91m Green Bank Telescope survey
- BEFS:
- bell curve:
- Bellatrix:
- Orion: well-known constellation in the northern hemisphere
- belt:
- superrotating wind: wind traveling in the same direction as the planet is rotating
- zone: apparent "horizontal" band in an atmosphere
- Bennu:
- 101955 Bennu: near-Earth asteroid that is the target of a planned sample-return mission
- benzene:
- hydrocarbon (HC): any compound of just carbon and hydrogen
- BepiColombo: mission to Mercury
- Mercury: inner-most and smallest planet in the solar system
- Berkeley:
- Berkeley Extreme and Far-UV Spectrometer (BEFS): 1990s UV spectrometer used on two shuttle missions
- Berkeley Open Cluster Catalogue (Be): list of open clusters
- Bernard Catalogue of 349 Dark Objects in the Sky:
- Bernard Lyot Telescope:
- Bernstein polynomial: polynomial form capable of producing arbitrary shapes
- beryllium:
- Besselian date:
- epoch: time on which to base celestial coordinates
- Besselian epoch:
- Besselian year:
- beta (β): ratio of plasma pressure to magnetic pressure
- Beta Centauri: second brightest star in Centaurus
- beta decay: radioactivity such that an electron or positron is emitted
- beta drift: tendency for a cyclone to drift poleward and westward
- Beta Orionis:
- Rigel: brightest star in constellation Orion
- beta particle:
- alpha particle: essentially a helium nucleus stemming from radioactivity
- beta decay: radioactivity such that an electron or positron is emitted
- particle spectrometer: device to determine the characteristics of incoming particles
- Beta Per:
- Algol (Beta Per,β Per): multiple star system demonstrating affects of mass transfer
- Beta Persei:
- Algol (Beta Per,β Per): multiple star system demonstrating affects of mass transfer
- Beta Pictoris:
- Beta Pictoris b (β Pic b): super Jupiter discovered in 2008
- beta plane:
- beta ray:
- beta-decay stable isobars:
- Betelgeuse: second brightest star in constellation Orion
- Orion: well-known constellation in the northern hemisphere
- bethe:
- foe: unit of energy on the order of a supernova's output
- BG4:
- BlackGEM: telescope array in development to follow up gravitational wave signals
- BH:
- BH merger:
- BH model:
- BHAR:
- BHB:
- bias:
- bicarbonate:
- acidity (pH): measure of the activity of hydrogen ions in a solution
- carbonate system: system governing water and CO2 in the presence of each other
- BICEP:
- BICEP2: survey to measure the polarization of the CMB
- BICEP2: survey to measure the polarization of the CMB
- BICEP3:
- BICEP2: survey to measure the polarization of the CMB
- Big Bang: theoretical event when the universe expanded from a point
- Big Bang nucleosynthesis (BBN): creation of atomic nuclei in the very early universe
- Big Bang theory:
- Big Bang: theoretical event when the universe expanded from a point
- Big Ear:
- BigBOSS: BOSS survey follow-on
- BigBOSS Spectrograph:
- binary:
- binary asteroid:
- binary black hole:
- binary burning:
- binary minor planet (BMP): minor planet with another body orbiting it
- binary neutron star (BNS,NSB): two neutron stars co-orbiting
- binary population synthesis:
- binary SMBH (BSMBH,SMBBH,SMBHB): co-orbiting supermassive black holes
- binary star: system of two stars co-orbiting
- Achernar: ninth-brightest star in the sky
- Algol (Beta Per,β Per): multiple star system demonstrating affects of mass transfer
- Alpha Centauri: nearest star system
- Beta Centauri: second brightest star in Centaurus
- Black Widow Pulsar (B1957+20, PSR J1959+2048, PSR B1957+20): binary system consisting of a pulsar and small companion
- DQ Tau: young binary star system
- Epsilon Indi (ε Indi,ε Ind): nearby star system including two brown dwarf companions
- G239-25: nearby red dwarf with brown dwarf companion
- GG Tau: much-studied quadruple star system
- GRO J1655-40: microquasar
- HD 133131: binary star system with exoplanets
- Hulse-Taylor Binary (PSR B1913+16,PSR J1915+1606, PSR 1913+16): binary system consisting of a pulsar and neutron star
- J1713-0747: binary system with millisecond pulsar and white dwarf
- Luhman 16: nearby binary brown dwarf
- Luyten 726-8: nearby binary star system
- Procyon: brightest star in Canis Minor
- Rigel: brightest star in constellation Orion
- Scholz's Star: nearby binary star with red dwarf and brown dwarf
- Sirius: brightest star in the sky
- T Tauri: variable star taken as example of young star
- binary star type:
- binary stars:
- binary supermassive black hole:
- binary SMBH (BSMBH,SMBBH,SMBHB): co-orbiting supermassive black holes
- binary system:
- binary TNO:
- binary trans-Neptune object:
- binary X-ray pulsar:
- pulsar (PSR): astronomical body whose electromagnetic radiation displays a cycle
- binary X-ray system:
- binary YORP:
- binding energy: energy needed to separate two objects
- binomial coefficients:
- biofluorescence: common fluorescence in organisms to dissipate harmful UV radiation
- fluorescence: mechanism by which molecules emit a longer wavelength than they absorb
- biology:
- biomarker:
- biosignature: sign of life
- bipolar outflow: streams of matter from the poles of a protostar
- Birkhoff's theorem: shows GR qualities of a spherically-symmetric mass
- bispectrum:
- BL Lac object:
- BL Lacertae:
- blazar: very compact variable quasar
- black body (BB): idealized object that reflects no light
- black body radiation:
- spectral index (α): power by which an object's flux depends on frequency
- black body temperature:
- black dwarf:
- white dwarf: stellar remnant of mostly electron-degenerate matter
- Black Eye Galaxy:
- black hole (BH): region of such high mass that light cannot escape
- black hole accretion rate (BHAR): measure, especially used for AGNs
- black hole binary (BHB,BBH): two black holes co-orbiting
- black hole merger: two black holes meeting and forming one
- black hole model: description of a BH using math or computation
- black holes:
- Black Widow Pulsar (B1957+20, PSR J1959+2048, PSR B1957+20): binary system consisting of a pulsar and small companion
- black-body radiation: continuous spectrum characteristic of the temperature of a body
- black-body spectrum:
- black body (BB): idealized object that reflects no light
- black-body radiation: continuous spectrum characteristic of the temperature of a body
- power law: relationship with one quantity a power of another
- blackbody:
- black body (BB): idealized object that reflects no light
- BlackGEM: telescope array in development to follow up gravitational wave signals
- Blanco 4m:
- Blandford-Payne mechanism (BP process): means of extracting BH rotational energy by magnetized accretion disk
- Blandford-Payne process:
- Blandford-Znajek mechanism (BZ process): means of extracting BH rotational energy by magnetized accretion disk
- Blandford-Znajek process:
- blanketing effect:
- line blanketing: so many bunched spectral lines that they cannot be distinguished
- BLAST: balloon-borne 1.8m submillimeter telescope
- BLAST-TNG:
- BLAST: balloon-borne 1.8m submillimeter telescope
- BLASTPol:
- BLAST: balloon-borne 1.8m submillimeter telescope
- blazar: very compact variable quasar
- blaze angle:
- blazed grating:
- blend analysis:
- blended spectra: an observed spectrum comprising light from multiple objects
- Blendanal:
- blended spectra: an observed spectrum comprising light from multiple objects
- blended spectra: an observed spectrum comprising light from multiple objects
- Blender:
- blended spectra: an observed spectrum comprising light from multiple objects
- blind survey: survey conducted independently of prior information
- blow off:
- blowoff:
- blue:
- B: photometric filter for blue light
- blue compact dwarf galaxy:
- blue dropout galaxy:
- dropout: means of identifying distant galaxies
- blue galaxy:
- blue noise:
- red noise: noise tending toward lower frequencies
- blue shift:
- data cube: "table" of numerical data covering three dimensions
- line broadening: processes causing a spectral line to have width
- redshift (z): change to longer wavelengths due to Doppler affects
- blue straggler:
- open cluster: group of stars within a galaxy apparently formed by a single cloud
- turn-off point (TO): point in H-R diagram of a cluster where stars turn red
- BMBF:
- BMP:
- BNS:
- Bode designation:
- Bode's law:
- Titius-Bode law: relationship between the distances between solar system planets
- Bohr model: has electrons circling nucleus in quantized orbits
- Bohr model of the atom:
- Bohr model: has electrons circling nucleus in quantized orbits
- Bohr radius:
- Bohr model: has electrons circling nucleus in quantized orbits
- boil off:
- Jeans escape: ongoing escape of gas particles from atmosphere
- boiling point:
- Bok globule: dense molecular cloud
- Bol'shoi Teleskop Azimultal'nyi:
- Bologna Sky Survey:
- Bologna Survey:
- Bologna Survey of Radio Sources: 1970s-1980s radio survey
- bolometer: instrument measuring heat produced by radiation
- GISMO: 2 mm bolometer camera on IRAM 30m telescope
- MUSTANG: bolometer array on the Green Bank Telescope
- SCUBA: submillimeter instrument on James Clark Maxwell Telescope
- bolometric:
- bolometer: instrument measuring heat produced by radiation
- bolometric correction: difference between an object's bolometric and visible magnitudes
- bolometric luminosity (LBol): total luminosity of an object at all wavelengths
- bolometric magnitude (Mbol,Mbol): absolute magnitude of all wavelengths
- Bolshoi simulation: cosmological simulation
- Boltzmann constant (k,kB): relates particle energy and temperature
- Boltzmann distribution:
- Boltzmann equation: equation relating atomic excitation to temperature
- Boltzmann factor:
- Boltzmann relation:
- bond:
- hydrocarbon (HC): any compound of just carbon and hydrogen
- Bondi accretion:
- Bondi radius: radius in which a body moving through a medium will draw it in
- Bondi radius: radius in which a body moving through a medium will draw it in
- bone:
- filament: linear volume of high molecular gas density within a galaxy
- Bonner Durchmusterung Catalog (BD): well-known astrometric catalog from late 1800s
- born-again star:
- Bose-Einstein distribution:
- Bose-Einstein statistics: possible distribution of particles not bound by Pauli exclusion
- boson:
- BOSS:
- BOSS Spectrograph:
- bottom quark:
- bouncing barrier:
- bound GMC:
- bound-bound:
- bound-free:
- boundary condition:
- bow shock: shock wave of a magnetosphere through the surrounding medium
- Boyajian's Star:
- Boyle's law:
- BP process:
- Bp star:
- BP/RP:
- Gaia: survey satellite at 400-1000 nanometers
- BPM:
- BPS:
- bracket notation:
- Brackett:
- Brackett series: hydrogen lines for electrons settling from n > 4 to n = 4
- break-up velocity:
- breaking a degeneracy:
- degeneracy: general word meaning a violation of normal rules
- breaking atmospheric wave:
- breaking radiation:
- bremsstrahlung: photon emission when a charged particle is decelerated
- Breakthrough Starshot:
- Starshot: plan for mission to fly by Alpha Centauri
- bremsstrahlung: photon emission when a charged particle is decelerated
- bright giant:
- bright nebula:
- cloud: higher-density region of space
- bright star:
- Achernar: ninth-brightest star in the sky
- Alpha Centauri: nearest star system
- Arcturus: fourth brightest star in the sky
- Beta Centauri: second brightest star in Centaurus
- Betelgeuse: second brightest star in constellation Orion
- Canopus: second brightest star in the sky
- Epsilon Eridani: third nearest visible star system in sky
- Procyon: brightest star in Canis Minor
- Rigel: brightest star in constellation Orion
- Sirius: brightest star in the sky
- Vega: brightest star in constellation Lyra
- Bright Star Catalog (HR,BS,YBS): early 20th century catalog of 9000 stars
- bright supergiant:
- brightest cluster galaxy (BCG): a cluster's most luminous galaxy
- brightest star:
- brightness:
- British Columbia:
- broad band photometry:
- photometry: studying starlight through bandpass filters
- broadband:
- bandwidth: number of hertz between minimum and maximum frequencies
- broadening:
- brown dwarf (BD): star-like object with less mass than a star
- brown dwarfs:
- Brown noise:
- red noise: noise tending toward lower frequencies
- Brownian motion:
- red noise: noise tending toward lower frequencies
- Brownian noise:
- red noise: noise tending toward lower frequencies
- Bruce Proper Motion Survey (BPM): 1941 southern-hemisphere survey catalog of Luyten's
- Brunt-Väisälä frequency: natural frequency of buoyancy waves
- brute force:
- BS:
- BSE:
- BSMBH:
- binary SMBH (BSMBH,SMBBH,SMBHB): co-orbiting supermassive black holes
- BT-Settl: model atmosphere of small stars and brown dwarfs
- BTA-6:
- BTFR:
- BU:
- buckminsterfullerene:
- bucky ball:
- bulge: denser group of stars within a larger group
- bulk atmosphere:
- bulk density: total mass divided by total volume
- bulk metallicity:
- bulk modulus:
- sound speed: speed at which compression waves traverse a gas
- bulk planetary atmosphere:
- bulk silicate earth (BSE): the early overall composition of the silicate part of Earth
- Bullet Cluster: example of two galaxy clusters in collision
- buoyancy frequency:
- Burnham:
- Burnham Double Star Catalogue (BDS,BU): 1906 catalog with multiple star systems and non-orbiting double stars
- burning:
- fusion: formation of an atomic nucleus nuclei from multiple smaller nuclei
- burst:
- burst gravitational wave:
- BWE:
- BY Draconis star:
- BY Draconis variable:
- BYORP:
- Byurakan Observatory:
- BZ:
- BZ process:
index