/ftp/cats/A+A/538//A76



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J/A+A/538/A76 Stellar spectra automatic spectral classification (Navarro+, 2012)
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Beginning of ReadMe : J/A+A/538/A76 Automatic stellar spectral classification (Navarro+, 2012) ================================================================================ Automatic spectral classification of stellar spectra with low signal-to-noise ratio using artificial neural networks. Navarro S.G., Corradi R.L.M., Mampaso A. <Astron. Astrophys., 538, A76 (2012)> =2012A&A...538A..76N ================================================================================ ADC_Keywords: Planetary nebulae ; MK spectral classification Keywords: methods: data analysis - planetary nebulae: general - astronomical databases: miscellaneous Abstract: As part of a project aimed at deriving extinction-distances for thirty-five planetary nebulae, spectra of a few thousand stars were analyzed to determine their spectral type and luminosity class. We present here the automatic spectral classification process used to classify stellar spectra. This system can be used to classify any other stellar spectra with similar or higher signal-to-noise ratios. Spectral classification was performed using a system of artificial neural networks that were trained with a set of line-strength indices selected among the spectral lines most sensitive to temperature and the best luminosity tracers. The training and validation processes of the neural networks are discussed and the results of additional validation probes, designed to ensure the accuracy of the spectral classification, are presented. Description: More than 2000 stars distributed in the field of view of 35 planetary nebulae, and 31 stars from the spectral catalog of Jacoby et al. (1984, Cat. III/92) were observed with the LDSS2 (Low Dispersion Survey Spectrograph) at the William Herschel Telescope (WHT) on La Palma, Spain.