In this Letter, we report the discovery of an intriguing hypervelocity star (HVS; J1443+1453) candidate that is probably from the Sagittarius Dwarf Spheroidal galaxy (Sgr dSph). The star is an old and very metal-poor low-mass main-sequence turn-off star (age ∼14.0 Gyr and [Fe/H]=−2.23 dex) and has a total velocity of km s⁻¹ in the Galactic rest frame and a heliocentric distance of kpc. The velocity of J1443+1453 is larger than the escape speed at its position, suggesting that it is a promising HVS candidate. By reconstructing its trajectory in the Galactic potential, we find that the orbit of J1443+1453 intersects closely with that of Sgr dSph Myr ago, when the latter has its latest pericentric passage through the Milky Way. The encounter occurs at a distance kpc from the center of Sgr dSph, a distance that is smaller than the size of the Sgr dSph. The chemical properties of this star are also consistent with those of an Sgr dSph-associated globular cluster, or of the Sgr stream member stars. Our finding suggests that J1443+1453 is an HVS that is either tidally stripped from the Sgr dSph or ejected from the Sgr dSph by the gravitational slingshot effect, requiring a (central) massive/intermediate-mass black hole or a (central) massive primordial black hole in the Sgr dSph.

在这封信中，我们报告了一个有趣的超高速恒星（HVS; J1443 + 1453）的发现，它可能来自人马座矮球状星系（Sgr dSph）。这颗恒星是一颗古老且金属贫乏的低质量主序熄灭恒星（年龄约14.0 Gyr，[Fe / H] = − 2.23 dex），在银河系静止时的总速度为km s ^-1框架和kpc的日心距。J1443 + 1453的速度大于其位置的逃逸速度，这表明它是很有前途的HVS候选者。通过在银河系中重建其轨迹，我们发现J1443 + 1453的轨道与Sgr dSph Myr的轨道紧密相交，后者在银河系中有最近的绕心通道。相遇发生在远处距Sgr dSph中心的kpc，该距离小于Sgr dSph的大小。该星的化学性质也与Sgr dSph相关的球状星团或Sgr流成员星的化学性质一致。我们的发现表明，J1443 + 1453是一种HVS，其通过重力弹弓效应从Sgr dSph潮汐剥离或从Sgr dSph弹出，需要一个（中央）大质量/中间质量黑洞或一个（中央）大质量原始Sgr dSph中的黑洞。