Purveyors of fine halos III. Chemical abundance analysis of a potential
  omega Cen associate
  Globular clusters (GCs) are important donors to the build-up of the Milky Way
(MW) stellar halo, having contributed at the ten percent level over the
Galactic history. Stars that originated from the second generation of dissolved
or dissolving clusters can be readily identified via distinct light-element
signatures such as enhanced N and Na and simultaneously depleted C and O
abundances. In this paper we present an extensive chemical abundance analysis
of the halo star J110842, which was previously kinematically associated with
the massive MW GC $\omega$ Centauri ($\omega$Cen), and we discuss viable
scenarios from escape to encounter. Based on a high-resolution, high
signal-to-noise spectrum of this star using the UVES spectrograph, we were able
to measure 33 species of 31 elements across all nucleosynthetic channels. The
star's low metallicity of [FeII/H]=$-2.10$$\pm$0.02(stat.)$\pm0.07$(sys.) dex
places it in the lower sixth percentile of $\omega$Cen's metallicity
distribution. We find that all of the heavier-element abundances, from
$\alpha$- and Fe-peak elements to neutron-capture elements are closely
compatible with $\omega$Cen's broad abundance distribution. However, given the
major overlap of this object's abundances with the bulk of all of the MW
components, this does not allow for a clear-cut distinction of the star's
origin. In contrast, our measurements of an enhancement in CN and its position
on the Na-strong locus of the Na-O anticorrelation render it conceivable that
it originally formed as a second-generation GC star, lending support to a
former association of this halo star with the massive GC $\omega$Cen.
