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J/PAZh/32/48        UBV photometry of HD 331319              (Arkhipova+, 2006)
Study of the IR-Excess Supergiant HD 331319.
    Arkhipova V.P., Ikonnikova N.P., Komissarova G.V., Esipov V.F.
   <Pis'ma Astron. Zh. 32, 48 (2006)>
   =2006PAZh...32...48A
   =2006AstL...32...45A
ADC_Keywords: Stars, supergiant - Photometry, UBV

Keywords: post-AGB supergiants - photometric and spectroscopic observations -
          photometric variability

Abstract:
    We report the discovery of brightness variability in the IR-excess
    early F supergiant HD 331319, a candidate post-AGB star. Over three
    years of systematic UBV observations, the star showed low-amplitude
    (up to 0.17m in V) quasi-periodic brightness variations on a
    time scale of 45 days. A preliminary analysis of our photometry
    indicates that HD 331319 and other typical post-AGBF supergiants have
    a similar pattern of variability. A study of the extinction toward HD
    331319 leads us to conclude that the fraction of the circumstellar
    extinction is small for this star. We present low-resolution
    spectroscopy for HD 331319 and discuss the spectral classification of
    post-AGB F supergiants using HD 331319, HD 161796, HD 187885, and
    HD 56126 as examples.

Description:
    We began our UBV observations of HD 331319 in 2002. From June 2002
    through April 2005, we obtained 104 magnitude estimates for the star
    with a photoelectric photometer attached to a 60cm Zeiss-600 telescope
    at the Crimean Station of the Strenberg Astronomical Institute.
Objects:
    -------------------------------------------------------------------
       RA   (2000)   DE      Designation(s)
    -------------------------------------------------------------------
    19 49 29.5   +31 27 16   HD 331319 = IRAS 19475+3119 = PN PM 2-42
    -------------------------------------------------------------------

File Summary:

       FileName      Lrecl  Records   Explanations

ReadMe            80        .   This file
table1.dat        40      132   UBV observations of HD 331319


Byte-by-byte Description of file: table1.dat

   Bytes Format Units   Label     Explanations

   1-  7  I7    d       JD        Julian date
   9- 13  F5.3  mag     Umag      U magnitude
  15- 20  F6.3  mag     Bmag      B magnitude
  22- 27  F6.3  mag     Vmag      V magnitude
  29- 33  F5.3  mag     U-B       U-B color index
  35- 39  F5.3  mag     B-V       B-V color index

(End)                       Veta Avedisova [INASAN]                  13-Apr-2006