Poster - Splinter EScience

Friday, 17 September 2021, 14:00   (virtual ESc)

New Classification criteria in the red spectral region from 4200 to 9000Å for CP star

Prapti Mondal , Ernst Paunzen
Dept. of Theor. Phys. & Astrophysics , Masaryk University

we know that all for CP star the classical classification criteria are based on the blue wavelength region, i.e., from 3800 to 4600Å. The new generations of spectroscopic instruments and detectors are much more sensitive in the red region, i.e., redder than 4200Å. Therefore, it is necessary to establish new classification criteria in this wavelength region using already well-known CP stars and their spectra, as an example from the LAMOST survey. we also have already a homogenous set of spectra for CP stars so in future we will use these data for our purpose. Morgan(1933) had already identified five groups of peculiar A type stars i.e. Mn II, λ4200, Eu II, Cr II and Sr II stars. Later Si II lines was identified at λ4200 Å which is called Si II group. Hydrogen lines can easily defines the MK spectral types of mild Ap star. Ap stars contain groups with chemical peculiarities of different elements. The spectrum of normal A stars (not easy to find) is controlled by hydrogen lines which are temperature as well as luminosity sensitive. The lines Ca II K, Ca I λ4226, Fe I lines at λλ 4045,4271 and 4383 are very good temperature and hence spectral type indicators.