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We explore the origins of the young B-type stars found by Casetti-Dinescu etal.(2014) at the outskirts of the Milky-Way disk in the sky region of LeadingArm of the Magellanic Stream. High-resolution spectroscopic observations madewith the MIKE instrument on the Magellan Clay 6.5m telescope for nine stars areadded to the previous sample analyzed by Zhang et al. (2017). We compile asample of fifteen young stars with well-determined stellar types, ages,abundances and kinematics. With proper motions from Gaia DR2 we also deriveorbits in a realistic Milky-Way potential. We find that our previousradial-velocity selected LA candidates have substantial orbital angularmomentum. The substantial amount of rotational component for these stars is incontrast with the near-polar Magellanic orbit, thus rendering these starsunlikely members of the LA. There are four large orbital-energy stars in oursample. The highest orbital-energy one has an age shorter than the time to diskcrossing, with a birthplace $z=2.5$~kpc and $R_{\rm GC}\sim 28$~kpc. Therefore,the origin of this star is uncertain. The remaining three stars have diskrunaway origin with birthplaces between 12 and 25 kpc from the Galactic center.Also, the most energetic stars are more metal poor ([Mg/H] =$-0.50\pm0.07$) andwith larger He scatter ($\sigma_{\rm [He/H]} = 0.72$) than the inner disk ones([Mg/H] $=0.12\pm0.36$, $\sigma_{\rm [He/H]} = 0.15$). While the former group'sabundance is compatible with that of the Large Magellanic Cloud, it could alsoreflect the metallicity gradient of the MW disk and their runaway status viadifferent runaway mechanisms.

The Origins of Young Stars in the Direction of the Leading Arm of the Magellanic Stream: Abundances, Kinematics, and Orbits