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تسجيل مستخدم جديدThe Most Distant Stars in the Milky Way
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We report on the discovery of the most distant Milky Way (MW) stars known to date: ULAS J001535.72$+$015549.6 and ULAS J074417.48$+$253233.0. These stars were selected as M giant candidates based on their infrared and optical colors and lack of proper motions. We spectroscopically confirmed them as outer halo giants using the MMT/Red Channel spectrograph. Both stars have large estimated distances, with ULAS J001535.72$+$015549.6 at $274 pm 74$ kpc and ULAS J074417.48$+$253233.0 at 238 $pm$ 64 kpc, making them the first MW stars discovered beyond 200 kpc. ULAS J001535.72$+$015549.6 and ULAS J074417.48$+$253233.0 are both moving away from the Galactic center at $52 pm 10$ km s$^{-1}$ and $24 pm 10$ km s$^{-1}$, respectively. Using their distances and kinematics, we considered possible origins such as: tidal stripping from a dwarf galaxy, ejection from the MWs disk, or membership in an undetected dwarf galaxy. These M giants, along with two inner halo giants that were also confirmed during this campaign, are the first to map largely unexplored regions of our Galaxys outer halo.
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