The Peculiar Stars and Spectral Classification

Abstract

The spectral classification experiments with the 70-cm meniscus telescope and 8° objective prism of Abastumani Observatory (dispersion 166 Å mm⁻¹) have shown that if we apply the Kodak IIa-O plates at the 0.4 mm widening of spectra and the 20 minutes exposure time, we can successfully classify with relatively high accuracy in two dimensional MK system the stars down to the 11th magnitude, with simultaneous discrimination of peculiars.

We have undertaken such determinations first of all in Kapteyn Selected Areas aiming to fill the gaps in existing data for these standard areas.

Finally we could mention the high quality of the meniscus telescope optics together with good seeing in Abastumani as favourable factors making the Abastumani spectra of 10–11th magn. stars comparable with the slit spectra of the same dispersion.

The Abastumani spectra allow to apply the Morgan and Kitt-Peak criteria of MK classification only with a slight modification.

We have two-dimensionally classified in MK system about ten thousand stars down to the 11th magnitude in KA Nos. 2–43 ($4_ \cdot ^\circ 5 \times 4^\circ 5$ each). Among them 137 peculiar stars have been revealed. They are mainly Ap, Am and Ball (7 stars) and the stars with composed spectra (5). 97 stars have been first identified as peculiars.