Spectroscopic Classification of Evolved Stars

The purpose of this research is to identify which Proto-Planetary Nebulae (PPNe) candidates have the spectral signatures that would indeed confirm them to be PPNe. PPNe are Sun-like stars that have evolved into a red giant and then ejected their outer layers. The temperature of these stars should lie within the spectral class of B (hottest) to K (coolest). Since these stars have expanded in size, the spectra will mimic a supergiant (Ia/Ib) luminosity class as well. The candidate spectra previously had been reduced to wavelength versus intensity. This summer, they were further reduced and then preliminarily set into general spectral class groups. I am further analyzing the individual spectra in these groups and assigning them a spectral subclass and luminosity class. Other features are also searched for in the spectra that could also indicate a PPNe, such as s-process element absorption or molecular carbon bands. These are known from previous publications on PPNe spectra. The results thus far have shown that several of the spectra indeed display the characteristics of PPNe