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J/MNRAS/358/30      Automated classification of ASAS variables     (Eyer+, 2005)
Automated classification of variable stars for All-Sky Automated Survey 1-2
data.
    Eyer L., Blake C.
   <Mon. Not. R. Astron. Soc., 358, 30-38 (2005)>
   =2005MNRAS.358...30E
ADC_Keywords: Stars, variable ; Photometry

Keywords: astronomical data bases: miscellaneous - catalogues - surveys -
          Cepheids - stars: variables: other

Abstract:
    With the advent of surveys generating multi-epoch photometry and the
    discovery of large numbers of variable stars, the classification of
    these stars has to be automatic. We have developed such a
    classification procedure for about 1700 stars from the variable star
    catalogue of the All-Sky Automated Survey 1-2 (ASAS 1-2) by selecting
    the periodic stars and by applying an unsupervised Bayesian classifier
    using parameters obtained through a Fourier decomposition of the light
    curve. For irregular light curves we used the period and moments of
    the magnitude distribution for the classification. In the case of ASAS
    1-2, 83 per cent of variable objects are red giants. A general relation
    between the period and amplitude is found for a large fraction of
    those stars. The selection led to 302 periodic and 1429 semiperiodic
    stars, which are classified in six major groups: eclipsing binaries,
    'sinusoidal curves', Cepheids, small amplitude red variables, SR and
    Mira stars. The type classification error level is estimated to be
    about 7 per cent.

File Summary:

       FileName      Lrecl  Records   Explanations

ReadMe            80        .   This file
table1.dat        67      302   Results of the classification


See also:
       II/264 : ASAS Variable Stars in Southern hemisphere (Pojmanski+, 2002-05)
 J/AcA/48/35  : All Sky Automated Survey variable stars (Pojmamski 1998)
 J/AcA/50/177 : All Sky Automated Survey Catalog (Pojmanski+, 2000)


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

   Bytes Format Units   Label    Explanations

   1- 13  A13   ---     ASAS     ASAS Identification (hhmmss-ddmm.m, J2000)
  15- 20  F6.3  mag     <Imag>   Mean I magnitude
  22- 26  F5.3  mag    e_<Imag>  rms uncertainty on <Imag>
  28- 31  I4    ---    o_<Imag>  Number of measurements for <Imag>
  33- 40  F8.4  d       Per      Period
  42- 46  F5.3  mag     Iamp     Amplitude of the variation
  48- 52  F5.3  ---     R21      Amplitude ratio of harmonic vs fundamental
  54- 58  F5.3  rad     phi21    Phase difference of harmonic vs fundamental (2)
      60  I1    ---     nh       Number of harmonics
      62  I1    ---     Class    [0/8] Classification code with AUTOCLASS
                                       Bayesian classifier (1)
  64- 67  F4.2  ---     PMemb    Class membership probability

Note (1): Classification code as follows:
      0 = eclipsing binaries of EA and EB type (63 stars)
      1 = group composed of difficult cases but of larger amplitude than
          the small amplitude group (Class #2) (58 stars)
      2 = Small amplitude variables (44 stars)
      3 = a large majority are eclipsing binaries, some seem marginal, and
          others clearly have a wrong period. (38 stars)
      4 = EW-type eclipsing binaries includes very few potential pulsating
          stars (such as delta Scuti stars) or Ap stars with very
          sinusoidal curves. (36 stars)
      5 = Cepheids (32 stars)
      6 = Uncertain cases (19 stars)
      7 = Long-period variables (8 stars)
      8 = RR Lyrae stars  (4 stars)
Note (2): phase difference was set in the interval 3π/4 to  3π/4+2π



History:
    From electronic version of the journal
(End)                                      Patricia Vannier [CDS]    28-Dec-2006