2025MNRAS.539..223G

We present a new value-added catalogue of late-type stars (LTS), M giants, M dwarfs as well as new C (carbon) stars of N and CH-types from the analysis of the Digitized First Byurakan Survey (DFBS) spectral data base. A total of 243 M giants, 834 M dwarfs and 14 C stars, namely 1091 objects have been confirmed. When analysing the DFBS plates, we selected all these objects as LTS candidates. For spectral type confirmation, we have used the Gaia DR3 low-resolution BP/RP spectroscopic data base. To clarify the nature of newly confirmed objects, Gaia DR3 photometric data and Transiting Exoplanet Survey Satellite (TESS) Input Catalog (TIC) data (masses, radii, effective temperatures, colours, distances, etc.) have been used. Using distances derived from the parallaxes in Gaia DR3, we constructed BP-RP colour versus G-band absolute magnitude diagram (colour-absolute magnitude diagram - CaMD). These confirmations of a large number of completely new objects represent a very significant extension in the census of M giants, faint N-type asymptotic giant branch C stars, CH-type giants at high Galactic latitudes. Some objects are located more than 8 kpc from the Galactic plane. Part of the newly confirmed DFBS M dwarfs present binary systems, mainly pairs of M dwarfs such as M dwarf plus M dwarf, and also M dwarf plus White Dwarf (WD). Most probably, some of the newly confirmed early-type CH-giants at high Galactic latitudes also present binary systems. The ZTF and TESS phased light curves are presented for more interesting objects among the samples of the DFBS LTS confirmed.