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J/A+A/475/1159   Supervised classification of variable stars (Debosscher+, 2007)

Automated supervised classification of variable stars. I. Methodology. Debosscher J., Sarro L.M., Aerts C., Cuypers J., Vandenbussche B., Garrido R., Solano E. <Astron. Astrophys., 475, 1159-1183 (2007)> =2007A&A...475.1159D
ADC_Keywords: Stars, variable Keywords: stars: variables: general - stars: binaries: general - techniques: photometric - methods: statistical - methods: data analysis Abstract: The fast classification of new variable stars is an important step in making them available for further research. Selection of science targets from large databases is much more efficient if they have been classified first. Defining the classes in terms of physical parameters is also important to get an unbiased statistical view on the variability mechanisms and the borders of instability strips. Our goal is twofold: provide an overview of the stellar variability classes that are presently known, in terms of some relevant stellar parameters; use the class descriptions obtained as the basis for an automated `supervised classification' of large databases. Such automated classification will compare and assign new objects to a set of pre-defined variability training classes. For every variability class, a literature search was performed to find as many well-known member stars as possible, or a considerable subset if too many were present. Next, we searched on-line and private databases for their light curves in the visible band and performed period analysis and harmonic fitting. The derived light curve parameters are used to describe the classes and define the training classifiers. We compared the performance of different classifiers in terms of percentage of correct identification, of confusion among classes and of computation time. We describe how well the classes can be separated using the proposed set of parameters and how future improvements can be made, based on new large databases such as the light curves to be assembled by the CoRoT and Kepler space missions. The derived classifiers' performances are so good in terms of success rate and computational speed that we will evaluate them in practice from the application of our methodology to a large subset of variable stars in the OGLE database and from comparison of the results with published OGLE variable star classifications based on human intervention. These results will be published in a subsequent paper. Description: Light curve parameters for 1777 variable stars, belonging to 35 well known stellar variability classes, are presented. These parameters are used to define the classes and to construct the supervised classifiers described in the paper. They serve as a direct input when using the Gaussian mixture classification code, which is provided as well. Instructions on how to run the code are given in the separate file 'gmreadme.txt'. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file list.dat 174 1642 List of stars used defatts.dat 443 1777 Light curve parameters codes.dat 49 35 Classification codes gmreadme.txt 504 183 Readme file for the gmclass code init.dat 24 69 Initialization file for the gmclass code gmclass.f 225 573 gmclass classification code (FORTRAN)
Byte-by-byte Description of file: list.dat
Bytes Format Units Label Explanations
1- 22 A22 --- Name Star name 24- 25 I2 h RAh ? Simbad right ascension (J2000) 27- 28 I2 min RAm ? Simbad right ascension (J2000) 30- 36 F7.4 s RAs ? Simbad right ascension (J2000) 38 A1 --- DE- Simbad Declination sign (J2000) 39- 40 I2 deg DEd ? Simbad Declination (J2000) 42- 43 I2 arcmin DEm ? Simbad Declination (J2000) 45- 50 F6.3 arcsec DEs ? Simbad Declination (J2000) 52- 57 A6 --- var Variability code, in codes.dat file 58- 63 A6 --- var2 Second variability code, in codes.dat file 64- 90 A27 --- FileName Name of the file containing the lightcurve 92-118 A27 --- FileName2 Name of the file containing the lightcurve 120-146 A27 --- FileName3 Name of the file containing the lightcurve 148-174 A27 --- FileName4 Name of the file containing the lightcurve
Byte-by-byte Description of file: defatts.dat
Bytes Format Units Label Explanations
1- 27 A27 --- FileName Name of the file containing the lightcurve (1) 32- 44 F13.8 1/d f1 1th frequency 46- 58 F13.8 1/d f2 2th frequency 60- 72 F13.8 1/d f3 3th frequency 74- 86 F13.8 mag amp11 1th harmonic amplitude of f1 88-100 F13.8 mag amp12 2th harmonic amplitude of f1 102-114 F13.8 mag amp13 3th harmonic amplitude of f1 116-128 F13.8 mag amp14 4th harmonic amplitude of f1 130-142 F13.8 mag amp21 1th harmonic amplitude of f2 144-156 F13.8 mag amp22 2th harmonic amplitude of f2 158-170 F13.8 mag amp23 3th harmonic amplitude of f2 172-184 F13.8 mag amp24 4th harmonic amplitude of f2 186-198 F13.8 mag amp31 1th harmonic amplitude of f3 200-212 F13.8 mag amp32 2th harmonic amplitude of f3 214-226 F13.8 mag amp33 3th harmonic amplitude of f3 228-240 F13.8 mag amp34 4th harmonic amplitude of f3 242-254 F13.8 rad phi12 phase of amp12, if phase of amp11=0 256-268 F13.8 rad phi13 phase of amp13, if phase of amp11=0 270-282 F13.8 rad phi14 phase of amp14, if phase of amp11=0 284-296 F13.8 rad phi21 phase of amp21, if phase of amp11=0 298-310 F13.8 rad phi22 phase of amp22, if phase of amp11=0 312-324 F13.8 rad phi23 phase of amp23, if phase of amp11=0 326-338 F13.8 rad phi24 phase of amp24, if phase of amp11=0 340-352 F13.8 rad phi31 phase of amp31, if phase of amp11=0 354-366 F13.8 rad phi32 phase of amp32, if phase of amp11=0 368-380 F13.8 rad phi33 phase of amp33, if phase of amp11=0 382-394 F13.8 rad phi34 phase of amp34, if phase of amp11=0 396-408 F13.8 mag/d trend Slope of linear trend 410-422 F13.8 --- varrat Variance ratio (2) 424-436 F13.8 --- varred Variance reduction (3) 438-443 A6 --- var Variability code, in codes.dat file
Note (1): The original light curves for these objects will be made available soon, together with an explanation on the identifiers. Note (2): Ratio of the variance after, to the variance before subtraction of a least-squares fit with the dominant frequency 'f1' and its 4 harmonics (values between 0 and 1). Note (3): Final variance reduction due to subtraction of all the periodic signals (values close to 1 if the fit is good, close to 0 if the fit is poor)
Byte-by-byte Description of file: codes.dat
Bytes Format Units Label Explanations
1- 5 A5 --- Code Code 9- 45 A37 --- Class Definition of the class 47- 49 I3 --- Ncl The total number of light curves present in the dataset for the class
Acknowledgements: Jonas Debosscher, jonas(at) Historical notes: * 20-Nov-2007: Initial version * 31-Mar-2008: New version of list.dat (Variability code corrected)
(End) Patricia Vannier [CDS] 19-Nov-2007
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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