North polar sequence

The North polar sequence is a group of 96 stars that was used to define stellar magnitudes and colors. The cluster of stars lies within two degrees of the Northern Celestial pole, which makes them visible to everyone on the northern hemisphere.

Originally proposed by Edward Charles Pickering, the system was used between 1900 and 1950. Today it has been replaced by the UBV photometric system.

External links

Data at Google books
Schematic images

Star

Evolution	Formation Pre-main-sequence star Main sequence Red giant branch Horizontal branch Asymptotic giant branch Dredge-up Instability strip Red clump PG1159 star Mira variable Planetary nebula Protoplanetary nebula Luminous red nova Luminous blue variable Wolf–Rayet star Stellar population Supernova Supernova impostor Hypernova Hertzsprung–Russell diagram Color–color diagram

Protostars	Molecular cloud H II region Bok globule Young stellar object Herbig–Haro object Hayashi track Henyey track Orion T Tauri FU Orionis Herbig Ae/Be

Luminosity class	Subdwarf Dwarf Blue Red White Yellow Black Brown Subgiant Giant Blue Red Bright giant Supergiant Blue Red Yellow Hypergiant Yellow Blue straggler Variable star

Spectral classification	O B A F G K M Be OB Subdwarf O Subdwarf B Late-type Chemically peculiar Am Ap/Bp Oscillating Barium Carbon CH CN Extreme helium Lambda Boötis Lead Mercury-manganese S Shell Technetium

Remnants	White dwarf Black dwarf Helium planet Neutron star Pulsar Binary X-ray X-ray binary X-ray burster Magnetar Stellar black hole Compact star Quark Strange Preon Planck Exotic Stellar core: EF Eridani B

Theoretical stars	Dark-matter star Dark-energy star Black star Gravastar Frozen star Q star Quasi-star Thorne–Żytkow object Iron star Blitzar

Nucleosynthesis	Deuterium burning Lithium burning Proton–proton chain CNO cycle Helium flash Triple-alpha process Carbon burning Neon burning Oxygen burning Alpha process Silicon burning S-process R-process Fusor Nova Remnants

Structure	Core Convection zone Microturbulence Oscillations Radiation zone Atmosphere Photosphere Starspot Chromosphere Corona Stellar wind Bubble Asteroseismology Eddington luminosity Kelvin–Helmholtz mechanism

Properties	Designation Dynamics Effective temperature Kinematics Magnetic field Magnitude Absolute Mass Metallicity Rotation UBV color Variability

Star systems	Binary Contact Common envelope Multiple Accretion disk Star cluster Open cluster Globular cluster Super star cluster Planetary system Earth's Solar System

Earth-centric observation of	Pole star Circumpolar star Magnitude Apparent Extinction Photographic Color Radial velocity Proper motion Parallax Photometric-standard star

Lists	Star names Arabic Chinese Extremes Most massive Highest temperature Largest volume Smallest volume Brightest Historical Most luminous Nearest Nearest bright Stars with exoplanets Brown dwarfs White dwarfs Milky Way novae Notable supernovae Supernova candidates Supernova remnants Planetary nebulae Timeline of stellar astronomy

Related articles	Substellar object Brown dwarf Sub-brown dwarf Planet Galactic year Galaxy Supercluster Helioseismology Guest star Constellation Asterism Gravity Intergalactic star Infrared dark cloud Starfield

Category:Stars · Star portal

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North polar sequence

See also

External links