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Variable Stars Common Observation
Mission in Particular Areas of the Sky



1347 stars discovered as of Nov 15, 2015
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Classification of Variable Stars

See also: What are Variable Stars?    Why Observe Variable Stars?    Variable Stars Easy to Observe

At a fundamental level a variable star is identified by its brightness (or other physical property such as radius or spectral type) changes over time due to intrinsic or extrinsic reasons. For intrinsic variables, variation happens due to physical changes (like pulsating) within the star or stellar system. In a case of extrinsic reasons, the stars variability is due to the eclipse of one star by another or the effect of stellar rotation.

In the section howewer we focus on a classification for stars with a measurable change in brightness, since astronomers have to classify them according to observable properties. Many years ago, several classes of variable stars were described in terms of a prototype star; and astronomers would define new classes to encompass minor observational differences from known variables. Modern variable star taxonomy is more generic. Variability types are grouped according to the major astrophysical reasons for variability. The following well-known major categories are now recognised:

  • Pulsating - radial or non-radial pulsation eg: Miras and semiregular variables, Cepheids, RV Tau stars.
  • Eruptive - variation caused by flares or shell ejection; eg: flare stars, T Tau variables, RCBs, S Doradus stars.
  • Cataclysmic - variation caused by explosions of the star or an accretion disc. Includes dwarf novae, classic novae & supernovae.
  • Rotating - variation caused by starspots, magnetism, or changing shape. eg: pulsars, elliptical stars and magnetic variables.
  • Eclipsing - binaries where one component passes in front of the other, as seen by the observer.
There are numerous subcategories within each of these. Below you can find the table containing most common classification of variable stars.

Most Common Variable Stars Types / Summary (clickable)

IntrinsicExtrinsic
Pulsating Stars Eruptive / Cataclysmic Eclipsing Binaries Rotating Variables

  • Cepheids (DCEP)

  • δ Cephei (DCEP)

  • RR Lyrae (RR)

  • δ Scuti (DSCT)

  • SX Phoenicis (SXPHE)

  • W Virginis (CW)

       - W Vir, P > 8d (CWA)

       - BL Her, P < 8d (CWB)

  • RV Tauri (RV)

  • β Cephei (BCEP)

  • α Cygni (ACYG)

  • ZZ Ceti (ZZ)
       Pulsating white dwarf type

  • Long-period Variables

  • Mira (M)

  • Semiregular (SR)

  • Slow irregular (L)

  • PV Telescopii (PVTEL)


  • Supernovae (SN)

  • Novae (N)

  • Recurrent Novae (NR)

  • Dwarf Novae

  • U Geminorum (UG)

  • Z Camelopardalis (UGZ)

  • SU Ursae Majoris (UGSU)

  • SS Cygni (UGSS)

  • Irregular

  • γ Cassiopeiae (GCAS)

  • Symbiotic Stars

  • Z Andromedae (ZAND)

  • R Coronae Borealis (RCB)

  • FU Orionis (FU)

  • RS Canum Venaticorum (RS)

  • S Doradus (SDOR)

  • UV Ceti (UV)

  • Wolf-Rayet (WR)


  • β Persei (EA)

  • β Lyrae (EB)

  • W Ursae Majoris (EW)

  • EW/DW subtype
  • EW/KW subtype

  • AR Lacertae (AR)


  • α² Canum Venaticorum (ACV)

  • BY Draconis (BY)

  • T Tauri (TTS)

  • FK Comae Berenices (FKCOM)

  • Pulsars (PSR)

  • SX Arietis (SXARI)




  • Below you can find charts for a quick variability type determination, based on different properties (for the most common types only).

    Variable Star Type Definitive Charts
    By Period By Mag Amplitude By Spectral Class


    References:

    Statistics Overview

    Variables by Constellation
    Variables by Type
    Variables by Magnitude
    Variables by Period

    Build Own Criteria
    Variable Stars Observer Bulletin

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