Chemically Tagging the HR 1614 Moving Group

Abstract

We present abundances for a sample of F, G, and K dwarfs of the HR 1614 moving group based on high-resolution, high signal-to-noise ratio spectra from the Anglo-Australian Telescope UCLES instrument. Our sample includes stars from Feltzing and Holmberg, as well as from Eggen. Abundances were derived for Na, Mg, Al, Si, Ca, Mn, Fe, Ni, Zr, Ba, Ce, Nd, and Eu. The α, Fe, and Fe-peak element abundances show a bimodal distribution, with four stars having solar metallicities, while the remaining 14 stars are metal-rich, [Fe/H] ≥ 0.25 dex. However, the abundances of these two groups converge for the heavier n-capture elements. Based on their photometry and kinematics, three of the four deviating stars are likely nonmembers or binaries. Although one star cannot be excluded on these grounds, we do expect low-level contamination from field stars within the HR 1614 moving group's range of magnitude, color, and space velocities. Disregarding these four stars, the abundance scatter across the group members for all elements is low. We find that there is an 80% probability that the intrinsic scatter does not exceed the following values: Fe, 0.01 dex; Na, 0.08 dex; Mg, 0.02 dex; Al, 0.06 dex; Si, 0.02 dex; Ca, 0.02 dex; Mn, 0.01 dex; Ni, 0.01 dex; Zr, 0.03 dex; Ba, 0.03 dex; Ce, 0.04 dex; Nd, 0.01 dex; and Eu, 0.02 dex. The homogeneity of the HR 1614 group in age and abundance suggests that it is the remnant of a dispersed star-forming event. Its kinematical coherence shows that such a dispersing system need not be significantly perturbed by external dynamical influences such as Galactic spiral structure or giant molecular clouds, at least over a period of 2 Gyr.