LAMOST J045019.27 + 394758.7, with peculiar abundances of N, Na, V, Zn, is possibly a Sculptor dwarf galaxy escapee

Abstract

ABSTRACT We present the results of the high-resolution (R ∼ 60 000) spectroscopic analysis of the star LAMOSTJ045019.27 + 394758.7 (hereafter J045) from the list of carbon stars of LAMOST DR2. From our analysis, we find that J045 does not exhibit the spectral characteristics of carbon stars. It is found to be a metal-poor ([Fe/H] = −1.05) giant that shows very unusual elemental abundances, particularly for N, Na, V, and Zn. J045 shows α-elements (Mg, Si, Ca) with near-solar values (<[α/Fe]> = 0.09) in contrast to Galactic stars that show [α/Fe] in the range 0.2–0.3 dex. In J045, Sc and Ti are under abundant with [X/Fe] ≤ −0.25. Vanadium gives [V/Fe] = 0.51 and zinc is under-abundant with [Zn/Fe] = −0.62. The object exhibits near-solar abundances for Sr, Y, Ba, Pr, and Sm. The La is marginally enhanced, and Ce and Nd are marginally under-abundant in J045. With [Ba/Eu]  = −0.38, the object falls into the category of neutron-capture rich r-I stars. The estimated abundances of various elements show that the observed abundance pattern is not compatible with the abundances characteristic of Galactic metal-poor stars but matches quite closely with the abundance pattern of Sculptor Dwarf galaxy stars of similar metallicity. Based on the above observational evidences, we suggest that the object is a possible Sculptor Dwarf Galaxy escapee.