Low resolution spectroscopy of hot post-AGB candidates II. LS, LSS, LSE stars and additional IRAS sources

TL;DR

This study identifies new hot post-AGB star candidates using low resolution spectroscopy from specific catalogues, expanding the known sample and aiding understanding of post-AGB evolution toward planetary nebulae formation.

Contribution

It introduces a new selection method for hot post-AGB candidates based on spectral and positional criteria, leading to the discovery of several new candidates.

Findings

Identified 13 new hot post-AGB star candidates.

Used low resolution optical spectra for spectral classification.

Expanded the catalog of potential post-AGB stars.

Abstract

Hot (OB) post-AGB stars are immediate progenitors of planetary nebulae (PNe). Very few hot post-AGB stars are known. Detecting new hot post-AGB candidates and follow-up multiwavelength studies will enable us to further understand the processes during the post-AGB evolution that lead to the formation of PNe. Case-Hamburg OB star surveys and their extension (LS, LSS, and LSE catalogues) and IRAS (point source) catalogues are good sources for detecting new hot post-AGB candidates from low resolution spectroscopy. Spectral types are determined from low resolution optical spectra of 44 stars selected from the LS, LSS, and LSE catalogues. Unlike the stars in the first paper, the stars in this paper were selected using criteria other than positional coincidence with an IRAS source with far IR (IRAS) colours similar to post-AGB supergiants and planetary nebulae. These included high galactic latitude, spectral types of O, B, A supergiants, emission lines in the spectrum and known spectral peculiarity. From the present study we find that LSS 1179, LSS 1222, LSS 1256, LSS 1276, LSS 1341, LSS 1394, LSS 2241, LSS 2429, LSS 4560, LSE 16, LSE 31, LSE 42, and LSE 67 to be new hot post-AGB candidates. Further study of these candidates is needed.