Cool carbon stars in the halo: new very red or distant objects

TL;DR

This paper reports the discovery and analysis of 23 new cool carbon stars in the Galactic halo, including very distant and red objects, providing insights into halo composition and mass loss at low metallicity.

Contribution

It introduces a new sample of halo carbon stars, including very red and distant objects, expanding understanding of halo stellar populations and their properties.

Findings

23 new halo carbon stars discovered

Some stars are extremely distant, over 95 kpc from the Sun

Red stars may be useful for studying low-metallicity mass loss

Abstract

The goal of this paper is to present and analyse a new sample of cool carbon (C)stars located in the halo. Twenty three new C stars were discovered. Spectra are typical of N-type stars with C2 and CN bands and sometimes Halpha in emission. ... Four objects are particularly red with J-K > 3, with 2 located at more than 5 kpc. from the Galactic plane. Eight additional objects with similar properties are found in the literature and our previous works. These 12 C stars could be useful to study mass loss at low metallicity. Two objects are at distances of 95 and 110 kpc. They are located in the region with galactocentric Z < -60 kpc in which the model of Law et al. predicts the Sgr stream to have a loop. (Abstact abridged)