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502Re: [vsx-dis] Re: [AAVSO-DIS] Question About the Variable Types in the Variable StarIndex

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  • Sebasti├ín Otero
    Sep 5, 2010
      > IAUS 272 on Actives OB stars
      > http://www.shelyak.com/dossier.php?id_dossier=50&lang=2

      The SPB and BCEP descriptions in that webpage are interchanged. The longer
      period stars are the SPB ones.

      You can also add DPV's
      Binary Be stars showing the orbital variability (EA, EB or ELL) superposed
      to a longer term variation (30-40 times longer than the orbital period)
      caused by the periodic formation and dissipation of a disk.

      A couple of YSO (Young Stellar Objects) classes are (and can be defined as):

      EX= EXors or Subfuors, subspecies of the FU class. They are named after EX
      Lupi. They are eruptive T Tauri stars that show brightening episodes of
      several magnitudes in time scales of several months or a few years. They
      possibly represent an intermediate state between normal T Tauri stars and FU
      Ori stars. (Examples: EX Lup, V1118 Ori, V1143 Ori)

      UX= UXors (UX Ori stars). Herbig Ae/Be stars that show irregular variations
      with a wide range of amplitudes from barely detectable to more than 4 mag in
      V. Large-amplitude variability is confined to stars with spectral types
      later than B8. There are two principal components: (1) irregular variations
      on timescales of days around a mean brightness level that changes on a much
      longer timescale (typically years), sometimes in a quasi-cyclic fashion, and
      (2) occasional episodes of deep minima, occurring at irregular intervals but
      more frequently near the low points of the brightness cycles (extracted from
      ref. 0081) (Examples: UX Ori, CQ Tau, BF Ori)

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