论文标题
候选高速恒星的发现源自射手座矮人球形星系
Discovery of A candidate Hypervelocity star originated from the Sagittarius Dwarf Spheroidal galaxy
论文作者
论文摘要
在这封信中，我们报告了可能来自Sagittarius Dwarf球形星系（SGR DSPH）的有趣的HVS（J1443+1453）候选人的发现。这颗恒星是一颗古老且非常贫穷的低质量主序列恒星（年龄$ \ sim14.0 $ gyr和[fe/h] $ = -2.23 $ dex），总速度为$ 559.01^{+135.07} _ {-87.40} $ km s $ s $ $ 2.90^{+0.72} _ { - 0.48} $ kpc。 J1443+1453的速度大于其位置的逃生速度，这表明它是有希望的HVS候选者。通过重建其在银河电位中的轨迹，我们发现J1443+1453的轨道与SGR DSPH $ 37.8^{+4.6} _ { - 6.0} $ Myr与SGR DSPH的轨道紧密相交，而后者则是最新的Perincentric percentric the Milky Way。相遇发生在$ 2.42^{+1.80} _ { - 0.77} $ kpc的$ 2.42^{+1.80} $ kpc，来自SGR DSPH的中心，小于SGR DSPH的大小。该恒星的化学特性也与一个SGR DSPH相关的球状簇或SGR流构件星的化学性质一致。我们的发现表明，J1443+1453是从SGR DSPH剥离的HVS，或者通过重力弹弓效应从SGR DSPH剥离，或者需要（中央/中间的）大孔黑洞或SGR DSPH中的（中央）大型黑洞或（中间）大型黑洞或（中央）大型Primordial黑洞。
In this letter, we report the discovery of an intriguing 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 $\sim14.0$ Gyr and [Fe/H] $= -2.23$ dex) and has a total velocity of $559.01^{+135.07}_{-87.40}$ km s$^{-1}$ in the Galactic rest-frame and a heliocentric distance of $2.90^{+0.72}_{-0.48}$ kpc. The velocity of J1443+1453 is larger than the escape speed at its position, suggesting it 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 the Sgr dSph $37.8^{+4.6}_{-6.0}$ Myr ago, when the latter has its latest pericentric passage through the Milky Way. The encounter occurs at a distance $2.42^{+1.80}_{-0.77}$ kpc from the centre of Sgr dSph, smaller than the size of the Sgr dSph. Chemical properties of this star are also consistent with those of one Sgr dSph associated globular cluster or of the Sgr stream member stars. Our finding suggests that J1443+1453 is an HVS 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.
