TY - JOUR

T1 - HD 16424: A new weak G-band star with high Li abundance

AU - Holanda, N.

AU - Драке, Наталия Алексеевна

AU - Pereira, C.B.

N1 - DOI: 10.1093/mnras/stac3343

PY - 2023/1/10

Y1 - 2023/1/10

N2 - The origin of the so-called weak G-band stars constitutes an unsolved problem in stellar astrophysics. In this context, we present a detailed abundance analysis of a new weak G-band star, HD 16424, which stands out with a very low 12C/13C ratio and Li and Na overabundance. Our work is based on the high-resolution échelle spectrum (R ≈ 48 000) and includes photometric and astrometric data from the literature. The analysis adopted in this work is performed under local thermodynamic equilibrium (LTE) approximation; we determine the atmospheric parameters (Teff, logg, [Fe/H], and ξ), abundances for proton-capture elements (C, N, O, Li), s-process elements (Y, Zr, La), and mixing tracers such as the 12C/13C isotopic ratio and sodium abundance, following by NLTE corrections applied to Li, O, and Na abundances. Our results show 12C deficiency ([C/Fe] = -0.57) and N enrichment ([N/Fe] = +0.97), that is typical for weak G-band stars. Also, we notice a carbon isotopic ratio characteristic of the CN-cycle equilibrium (⟨12C/13C⟩ = 4.0) and high lithium-7 abundance (logε(Li)NLTE = 2.85). In addition, this study shows a low projected rotational velocity (vsini = 2.0 km s-1) and low mass (1.61 M⊙) of HD 16424, which distinguishes this star from the intermediate-mass objects found in this class of peculiar objects.

AB - The origin of the so-called weak G-band stars constitutes an unsolved problem in stellar astrophysics. In this context, we present a detailed abundance analysis of a new weak G-band star, HD 16424, which stands out with a very low 12C/13C ratio and Li and Na overabundance. Our work is based on the high-resolution échelle spectrum (R ≈ 48 000) and includes photometric and astrometric data from the literature. The analysis adopted in this work is performed under local thermodynamic equilibrium (LTE) approximation; we determine the atmospheric parameters (Teff, logg, [Fe/H], and ξ), abundances for proton-capture elements (C, N, O, Li), s-process elements (Y, Zr, La), and mixing tracers such as the 12C/13C isotopic ratio and sodium abundance, following by NLTE corrections applied to Li, O, and Na abundances. Our results show 12C deficiency ([C/Fe] = -0.57) and N enrichment ([N/Fe] = +0.97), that is typical for weak G-band stars. Also, we notice a carbon isotopic ratio characteristic of the CN-cycle equilibrium (⟨12C/13C⟩ = 4.0) and high lithium-7 abundance (logε(Li)NLTE = 2.85). In addition, this study shows a low projected rotational velocity (vsini = 2.0 km s-1) and low mass (1.61 M⊙) of HD 16424, which distinguishes this star from the intermediate-mass objects found in this class of peculiar objects.

U2 - 10.1093/mnras/stac3343

DO - 10.1093/mnras/stac3343

M3 - Article

VL - 518

SP - 4038

EP - 4044

JO - Monthly Notices of the Royal Astronomical Society

JF - Monthly Notices of the Royal Astronomical Society

SN - 0035-8711

IS - 3

ER -