We discuss our targeted search for hypervelocity stars (HVSs), stars traveling with velocities so extreme that dynamical ejection from a massive black hole is their only suggested origin. Our survey, now half-complete, has successfully identified a total of four probable HVSs plus a number of other unusual objects. Here we report the two most recently discovered HVSs: SDSS J110557.45+093439.5 and possibly SDSS J113312.12+010824, traveling with Galactic rest-frame velocities at least +508 ± 12 and +418 ± 10 km s~(-1), respectively. The other late B-type objects in our survey are consistent with a population of post-main-sequence stars or blue stragglers in the Galactic halo, with mean metallicity [Fe/H]_(W_k) = —1.3 and velocity dispersion 108 ± 5 km s~(-1). It is interesting to note that the velocity distribution shows a tail of objects with large positive velocities that may be a mix of low-velocity HVSs and high-velocity runaway stars. Our survey also includes a number of DA white dwarfs with unusually red colors, possibly extremely low mass objects. Two of our objects are B supergiants in the Leo A dwarf, providing the first spec-troscopic evidence for star formation in this dwarf galaxy within the last ～30 Myr.
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机译：我们讨论了针对超高速恒星（HVS）的目标搜索，超高速恒星以极高的速度行进，以至于从巨大黑洞中动态弹出是它们唯一的起源。我们的调查（现已完成一半）已成功识别出总共四个可能的HVS，以及许多其他异常对象。这里我们报告两个最近发现的HVS：SDSS J110557.45 + 093439.5以及可能的SDSS J113312.12 + 010824，它们以至少+508±12和+418±10 km s〜（-1）的银河静止帧速度行进， 分别。我们调查中的其他晚期B型天体与银河系晕圈中的主序后恒星或蓝色散布者数量一致，平均金属度[Fe / H] _（W_k）= -1.3，速度色散为108± 5 km s〜（-1）。有趣的是，速度分布显示出具有大正速度的物体的尾巴，这些物体可能是低速HVS和高速失控星的混合体。我们的调查还包括一些DA矮人，它们带有异常红色，可能是极低质量的物体。我们的两个天体是狮子座A矮星中的B超巨星，这为近30 Myr内的这个矮星系中的恒星形成提供了第一个光谱学证据。
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