Abundance analysis of SDSS J134338.67+484426.6; an extremely metal-poor star from the MARVELS pre-survey

TL;DR

This study analyzes an extremely metal-poor star identified in the MARVELS survey, revealing its unique chemical composition, low metallicity, and potential binary nature, contributing to understanding early stellar populations.

Contribution

First detailed high-resolution abundance analysis of a bright, extremely metal-poor star from the MARVELS pre-survey, highlighting its unique chemical properties and binary status.

Findings

Star has [Fe/H] = -3.42, low metallicity.

Star is alpha-poor with low [Mg/Fe], [Si/Fe], [Ca/Fe].

Possible long-period binary indicated by radial velocity variations.

Abstract

We present an elemental-abundance analysis of an extremely metal-poor (EMP; [Fe/H] < -3.0) star, SDSS J134338.67+484426.6, identified during the course of the MARVELS spectroscopic pre-survey of some 20000 stars to identify suitable candidates for exoplanet searches. This star, with an apparent magnitude V = 12.14, is the lowest metallicity star found in the pre-survey, and is one of only ~20 known EMP stars that are this bright or brighter. Our high-resolution spectroscopic analysis shows that this star is a subgiant with [Fe/H] = -3.42, having "normal" carbon and no enhancement of neutron-capture abundances. Strontium is under-abundant, [Sr/Fe] =-0.47, but the derived lower limit on [Sr/Ba] indicates that Sr is likely enhanced relative to Ba. This star belongs to the sparsely populated class of alpha-poor EMP stars that exhibit low ratios of [Mg/Fe], [Si/Fe], and [Ca/Fe] compared to typical halo stars at similar metallicity. The observed variations in radial velocity from several epochs of (low- and high-resolution) spectroscopic follow-up indicate that SDSS J134338.67+484426.6 is a possible long-period binary. We also discuss the abundance trends in EMP stars for r-process elements, and compare with other magnesium-poor stars.