Spectral Properties and Variability of BIS objects

TL;DR

This study clarifies the nature and variability of IRAS point sources classified as late type stars, providing revised spectral classifications, distance estimates, and insights into their galactic population membership.

Contribution

The paper offers new spectral classifications and variability analyses of BIS objects, enhancing understanding of their nature and galactic distribution.

Findings

Revised spectral types for 47 stars and new classifications for 31 sources.

Distances estimated for various stars, indicating halo population membership.

Identification of different types of late-type stars, including G, K, M, and carbon stars.

Abstract

Through the analysis and interpretation of newly obtained and of literature data we have clarified the nature of poorly investigated IRAS point sources classified as late type stars, belonging to the Byurakan IRAS ~Stars catalog. From medium resolution spectroscopyof 95 stars we have strongly revised 47 spectral types and newly classified 31 sources. Nine stars are of G or K types, four are N carbon stars in the Asymptotic Giant Branch, the others being M type stars. From literature and new photometric observations we have studied their variability behaviour. For the regular variables we determined distances, absolute magnitudes and mass loss rates. For the other stars we estimated the distances, ranging between 1.3 and 10~kpc with a median of 2.8~kpc from the galactic plane, indicating that BIS stars mostly belong to the halo population.