New asymptotic giant branch carbon stars in the galactic halo

Nicolas Mauron (1, 2) , K. S. Gigoyan (3) , G. Kostandyan (3)

1 LUPM - Laboratoire Univers et Particules de Montpellier
2 AS
3 BAO - V.A. Ambartsumian Byurakan Astrophysical Observatory

For the first time the data on the eight confirmed or candidate carbon (C) stars found mainly from objective-prism plates are presented. By using the Catalina database of lightcurves, we find that all these stars are pulsating, allowing a distance to be estimated through the K-band Period-Luminosity (PL) relation. This relation does not depend on spectral type (M or C) and distances are reliable even for C candidates. Seven stars are more than 10 kpc from the galactic plane, suggesting they do not belong to the galactic disk. We also find one star located at about 180 kpc from the Sun, being one of the most distant star in the Galaxy. Many of these new C stars are relatively blue. Some comments are also provided on seven other known halo carbon stars for which either a pulsation period is obtained, or because they were not included in previous works on halo C stars.

Mots clés: carbon stars; surveys; Galactic halo; stellar content

Domaines: Astrophysique stellaire et solaire [astro-ph.SR]

Nicolas Mauron, K. S. Gigoyan, G. Kostandyan. New asymptotic giant branch carbon stars in the galactic halo. Astrophysics, 2018, 61, pp.83-90. ⟨10.1007/s10511-018-9517-x⟩. ⟨hal-01983689⟩