Study of Faint Galactic Carbon Stars from the First Byurakan Spectral Sky Survey. IV. GAIA DR2 Data

• Published in: Astrophysics 2020-02, Vol.63 (1), p.75-84
• Main Author: Kostandyan, G. R.
• Format: Article
• Language: English
• Subjects: Analysis; Artificial satellites in surveying; Astronomy; Astrophysics; Astrophysics and Astroparticles; Astrophysics and Cosmology; Asymptotic giant branch stars; Carbon stars; Galactic halos; Hertzsprung-Russell diagram; Identification and classification; Luminosity; Methods; N stars; Observations; Observations and Techniques; Physics; Physics and Astronomy; Properties; Sky surveys; Sky surveys (astronomy); Space Exploration and Astronautics; Space Sciences (including Extraterrestrial Physics; Spiral galaxies
• ISSN: 0571-7256; 1573-8191
• DOI: 10.1007/s10511-020-09615-6

Data from the second Gaia release (Gaia DR2) are used to analyze and evaluate several important parameters for 127 carbon (C) stars of which 56 are AGB stars of class N and 71 are giants of early CH classes detected in low-dispersion spectral plates from the First Byurakan Survey (FBS). For the FBS C-stars Gaia DR2 G broad – band magnitudes are in the range 9 m .4 < G < 18 m .2. The radial velocities RV are accessible for 75 of the 127 C-stars. For 9 of them RV exceeds 200 km/s. For 18 of the FBS C-stars that have luminosity data in DR2, of which 17 are CH giants, the absolute V magnitudes are estimated to lie in the range -3 m .4 ≤ M V ≤+0 m .5. For FBS 1918+869 the absolute magnitude M V = – 3 m .4 ± 0 m .2, which is typical for N type AGB C-stars. A Hertzsprung-Russell diagram (HRD or color-absolute magnitude diagram) was constructed with the estimated distances for the 127 C-stars. All the observed FBS C-stars are giants and AGB stars in the Galactic Halo. They are not far than 14 kpc from the Sun and 8 kpc from the Galactic plane.